Stanisław LABER LUBRICATION AND APPLICATION PROPERTIES OF "MOTOR LIFE PROFESSIONAL" EXPLOITATION AGENT

Transcription

1 Stanisław LABER LUBRICATION AND APPLICATION PROPERTIES OF "MOTOR LIFE PROFESSIONAL" EXPLOITATION AGENT University of Zielona Góra

2 University of Zielona Góra Machinery and Vehicles Construction Institute ul. Podgórna Zielona Góra Reviewers: Professor doctor engineer qualifying as assistant professor Wiesław Zwierzycki, Technical University of Poznań Professor doctor engineer qualifying as assistant professor Eugeniusz Feldsztein, University of Zielona Góra Lubrication and application properties of "MOTOR LIFE PROFESSIONAL" exploitation agent The presented study contains the examination results concerning the modification of friction junction operating conditions by MOTOR LIFE PROFESSIONAL preparation during the machinery exploitation stage. The preparation introduction capable of evoking chemical actions - as MOTOR LIFE PROFESSIONAL - into commercial oils, results in modification of the surface layer - in parallel a "strong" border layer is created due to physical sorption and chemisorption. This layer increases friction junction resistance against dynamic and temperature loads (as compared to the border layer created by enriching additives constituting a part of commercial oils). The tribological properties of friction junctions improve and the resistance of movement as well as wearing out of materials decrease. This has an effect on increased resistance and operational reliability of machinery and devices. The present monograph is meant for engineers and technical staff who are concerned with the exploitation of machinery and vehicles, especially those operating in heavy working conditions, submitted to dynamic and temperature charges, aggressive environment, pollution (dust and other) as well as for students specializing in mechanics. Copyright by Stanisław LABER ISBN

3 Table of Contents INTRODUCTION.. 1. EXPLOITATION AGENTS Functioning principles of exploitation agents Classification and function mechanisms of exploitation agents MODIFYING FRICTION JUNCTION OPERATING CONDITIONS WITH THE MOTOR LIFE PROFESSIONAL EXPLOITATION AGENT Oil lubricative properties Plastic grease lubricative properties Evaluating changes of select properties of CE/SF SAE 15W/40 engine oil during the exploitation process Lubricative and tribological properties of IBIS HPDO SAE engine oil conditioned by the exploitation period of engines in mining conditions 2.5.Evaluating noise emission and power demand for machinery and vehicles Shaping of technological quality and surface layer exploitation Machine cutting process Burnishing process... 3.CONCLUSION.... LITERATURE

4 INTRODUCTION The problem of proper lubrication of friction junctions has particular significance with the construction and exploitation of machinery. This problem has still a greater meaning since the development of technology also manifests itself in the increase of dynamic and temperature loads transferred by these junctions. The quantity and quality of the lubricating agent determines the sort of friction (dry, liquid, boundary, mixed) and therefore the wear and operational reliability of machine operation. In spite of its unquestionable advantages, oils do not resolve obvious problems of insufficient lubrication of friction zones in extreme operating conditions of tribological systems. They do not liquidate the so-called "cold start", that occurs in the engine when starting from cold, especially in low temperatures during winter season. The traditional course of studies aiming at the improvement of exploitation properties of lubricating agents is oriented at the application of enriching additives of a better quality being their integral part. What was achieved in exploitation of internal combustion engines, mechanical transmissions and hydraulic assemblies until now has been: the reduction of energy consumption by 2-3%, the elongation of operating liquids exchange period by 20-30%, the increase of mechanisms durability by 20-30% [32]. However, over the past few years, another idea (second course of studies) came into being. The idea is based on introducing new substances into friction junctions with the intermediation of oils. As a result of physical adsorption and chemisorption, the new substances modify the surface layer, creating a modified boundary layer more resistant to the activity of dynamic and temperature loads on rubbing surfaces. The additives were called "exploitation agents". The Exploitation of Machinery and Vehicles Technology Institute of Technical University of Zielona Góra for years has conducted research on the impact of exploitation agents on operating conditions of machinery and vehicle friction junctions; in particular: bearings, toothed transmissions, hydraulic assemblies, machine cutting junctions and other. The present study 4

5 demonstrates the results of laboratory and exploitation examinations of this domain. The study is composed of two principle sections. The first section contains general characteristics of exploitation agents. It includes the discussion on the results of their application. The section explains the main functioning mechanisms. The classification presented in the first section was based on this criterion. It distinguishes agents evoking chemical actions (e.g. MOTOR LIFE), agents produced on the basis of solid lubricating agents as well as those resulting in the so-called "no-wear friction" (Garkunow effect). The second section presents the examination results conducted on the exploitation agent evoking chemical actions - called MOTOR LIFE PROFESSIONAL. Positive effects in improvement of oil lubricative properties modified by this agent have been shown on the basis of laboratory analysis. The research implemented in exploitation conditions has confirmed its suitability for modified operating conditions. The examinations have shown the reduction of movement resistance (lower starting current and power demand), the increase of pressure in the internal combustion engine cylinders and the equalization of its level (higher technical engine efficiency), decrease of operating noise, decrease of smokiness and decreased oil consumption. It has been shown that the MOTOR LIFE agent does not considerably affect rheological properties of the oil (kinematic viscosity and basic number). Whereas, it does have impact on the decreased wear of rubbing pairs, which can be proven by the lower iron contents in the oil. The author of the study realizes that its content does not exhaust the entire problem involving the purposefulness of applying exploitation agents in modified operating conditions of friction junctions. However, the present study may familiarize the reader with the problem that was undertaken by the author. The team directed by the author of the study has conducted and still does conduct examinations on the application of other exploitation agents and enriching additives, with particular consideration of the technological and exploitation surface layer shaping (changes occurring in the course of the exploitation process). 5

6 1. EXPLOITATION AGENTS The introduction of lubricating agents into the friction zone is the most efficient method of reducing friction energy loss and wear limitation while the lubrication intensity determines the kind of friction, which may occur to be: dry, liquid, boundary or mixed. In case of machinery exploitation, the operating conditions would be considered ideal if the friction junctions operated in liquid friction or at least boundary friction conditions. The United States and other western countries have intensified their research on effective reduction of energy consumption of mechanisms and on increasing their mechanical efficiency since the 60s. The reduction of losses due to "internal" friction, occurring in tribological systems has been one of the leading problems in this research. At the same time, ecological aspects of their exploitation were taken into consideration. The traditional course of studies aiming at improving exploitation properties of cooling and lubricating liquids concerns the use of higher quality lubricating oils through the application of enriched additives of higher quality being their integral part. What has been achieved in the exploitation of internal combustion engines, mechanical transmissions and hydraulic assemblies until now was: the reduction of energy consumption by 2-3%, the elongation of operating liquid exchange period by 20-30%, the increase of mechanisms durability by 20-30% [32]. In spite of its unquestionable advantages (heat abstraction and carrying away wear products from the friction zone, lowering the friction factor, vibration damping, protecting against corrosion and other), lubricant agents oils do not resolve obvious problems of insufficient lubrication of friction zones in extreme operating conditions and/or temperatures and therefore do not liquidate the so called "cold start", that occurs e.g. when starting the engine in the cold; for a several seconds the engine is not efficiently lubricated and none of the presently used lubricating agents is able to prevent this from occurring. Therefore, another idea (second course of studies - fig 1.1) has been introduced. It is based on the introduction of new substances into friction junctions with the intermediation of oils, which as a result of physical adsorption and chemisorption modify the surface layer of surfaces of rubbing elements as well as the boundary layer of their surfaces. These additives were called "exploitation agents". Exploitation agents have various scientific terms, such as: friction modifiers [7], complementary additives 6

7 [9,30], correctors [3], unconventional low friction additives [11], unconventional lubricating additives [12,15], exploitation additives [2, 33], assisting additives [26], enriching additives [22,31] and others. In this study these additives are conventionally called exploitation agents (EA). The exploitation agents are chemical compounds or mixtures of chemical compounds prepared for special purposes, i.e. for the operating condition improvement of friction junctions through the increase in boundary layer durability. Typical enriching additives Improvement of properties: rheological, thermo-oxidizing, corrosive, detergent-washing, emulsifying and other Base oil Exploitation agents having the following functions: - chemical - on the basis of solid lubricating agents - having the effect of selective transmission Commercial oils - engine, - transmission, - hydraulic, - turbine, - compressor, - other Commercial oils of better exploitation properties in particular lubricating, anti-friction and other Fig Applying enriching additives and exploitation agents in oils Foreign and Polish scientific/technical literature as well as information prepared by the producers of exploitation agents present extreme opinions concerning the efficiency of their actions: from harmful, hardly efficient to efficient, from having considerable technical and economical significance to pro-ecological /piston combustion engines/. The favorable opinions show that the application of exploitation agents in engines and machinery causes the following: friction factor decrease; friction junction component wear decrease; lower temperature in friction zone; simplified cold start; allowing short term running without oil inflow possible ; power and efficiency increase; sealing of systems, reduction of scavenges and leaks; reduction of power, fuel and oil absorption; noise and vibration reduction; 7

8 exhaust gas toxicity reduction; durability and operational reliability increase of machinery and devices, in particular of the following: engines, toothed transmissions, hydraulic systems and other; due to the above the total exploitation costs are lowered The Exploitation Workroom of the Technical University of Zielona Góra has conducted laboratory research on lubricative properties of modified EP oils for a number of years. Laboratory research has been verified on technical objects in exploitation conditions. The conducted research has allowed, to certain extent, to determine their mechanisms of functioning and to determine their suitability for exploitation in specific machines, devices and vehicles FUNCTIONING PRINCIPLES OF EXPLOITATION AGENTS The EA functioning mechanism can be overall presented as follows. The molecules of EA are transported by the lubricating liquid to friction junctions, where - as a result of physical adsorption or chemisorption they are bound permanently with metallic surfaces rubbing against each other. A lubricating filter [32] or substitute boundary layer - SBL [16] is produced in this way on the surfaces of friction junctions. In case of insufficient lubrication in places where metallic surfaces touch each other, where standard oil does not ensure proper lubrication /stress concentration, sudden increase in the friction factor and temperature - seizure/ EA molecules begin their action and take over the role of a lubricating filter. At this moment the friction factor suddenly decreases to measures characteristic for liquid friction - approximately to the oil viscosity factor - fig At the same time the SBL protects metallic surfaces of the friction junction from corrosion. The effectiveness of SBL in contact micro-zones of surfaces cooperating with each other depends on the adsorption intensity processes in these contact micro-zones. As analysis shows [12, 14, 17 and other], the impact of EA is in general the most intensive in case of state worsening /wear/ of friction junctions in machines and devices. This is the reason for differences in efficiency of improving functional parameters of engines, machines and devices as well as EA function effectiveness of different types. The friction junction model with the use of EP is shown in fig

9 area of boundary lubrication µ=0,1-0,15 load [kg] area of mixed lubrication (seizure) µ=0,35-0,45 area of NDS interaction area of hydrodynamic lubrication µ=0,05-0,1 lost motion speed [m/s] Fig.1.2. Operating conditions of a friction junction modified with exploitation agents [32] Fig.1.3. Friction junction model with the use of exploitation agents: E1, E2 - rubbing pair elements, 1 lubricating agent enriched with an exploitation agent, 2 the proper boundary layer (created as a result of lubricating agent application), 3 substitute boundary layer: A liquid friction phase, B boundary friction phase, C boundary friction phase with the participation of substitute boundary layer, D dry friction 9

10 1.2. CLASSIFICATION AND FUNCTION MECHANISMS OF EXPLOITATION AGENTS There are differences between the EA's tested and used in practice. In general they can be divided into three groups: A. agents evoking chemical reaction B. agents containing specific molecules of solid lubricating agents in their composition, such as e.g. teflon, soft metals, graphite and others; C. agents allowing the formation of lubrication on the basis of selective transmission (ST) in the friction junction. As it has been concluded from the literature study, group A contains substances of undisclosed chemical composition. It can be considered highly probable that these are subtly chosen lubricating EP-type [extreme pressure] additives. They evoke chemical reactions with the metallic base during friction processes especially in higher temperatures. Thanks to the diffusion of these components with the surface layer, they create thin protective layers of phosphates, sulfides, etc. on the metal surface. At the same time a "strong" boundary layer of oil is obtained thanks to chemisorption and additional protection in the form of a thin diffusion layer. A thin surface layer created in this way (regenerating during the operating process of the friction junction) is characterized with a high resistance against the transmission of mechanical loads as well as higher temperatures, lowered friction factor and increased resistance to wearing /seizure/. The friction junction model lubricated with oil with the EA additive evoking a chemical reaction is illustrated in fig With reference to fig. 1.4 it is necessary to define the mechanism of conventional anti-wear additives (CAA) and EP being enriching additive components of majority commercial oils, licensed oils (e.g.: for engines, transmissions and other). The common feature of these additives is their interaction on the surface layer of rubbing surfaces and the creation of boundary layers on them, which ensures the condition of boundary lubrication. To be able to explain the mechanism of boundary layer creation for both groups of compounds, it is purposeful to explain what they are. Conventional anti-wear additives and EP belong to active lubricating agents improving lubrication ability. The presence of these compounds in the friction junction results in physical adsorption 10

11 occurring on rubbing surfaces, e.g. fatty acids forming a multi-layer structure composed of molecules in a shape of long chain with a polar group on its end or in chemisorption - e.g. sulfur or phosphorus react with the base, (e.g. with iron) the result of which is the creation of iron sulfides or iron phosphides. As [73] shows, as a result of chemisorption a thin semi-plastic layer is created, which protects touching surfaces from wearing and reduces friction resistance. Because it resists shearing very well, the friction factor is comparatively high. If it is between 0,001 and 0,006 for the hydrodynamic area, then for a thin layer like this its value amounts from 0,1 to 0,2, therefore it is almost by two orders of magnitude greater. Fig.1.4. Lubricated friction junction model: a) with the use of commercial oil, b) with the use of commercial oil enriched with the exploitation agent evoking chemical actions; 1,2 rubbing elements, 3 lubricating agent, 4 boundary layer created as a result of physical sorption, 5 boundary layer created as a result of chemisorption Summing it up, the boundary layer is made of a thin polimolecular layer (physical adsorption) and of thin plastic layer (chemisorption). The total thickness (fig. 1.4a) and quality of the thin layer determines its durability or, putting it differently, its ability of dynamic load and temperature transmission. The layer protects touching elements from wear and decreases friction resistance. The producers secretly guard the chemical composition of EA that evokes chemical actions. The literature presents divergence as to their chemical composition. According to [7] these are compounds of long chains with a polar group on their ends that can be dissolved in oil, whereas in [26] it is stated that EA's contain mainly lubricating additives of EP type. 11

12 Companies producing EA's know exactly each of these chemical compounds or the process, which is described on each of them. As the above analysis has shown, many of these compounds are in fact applied in licensed lubricating agents. It should be assumed that the difference is the following: chemical compounds in licensed oils stay in mutual balance and have been examined in standard tests, applied industrially in order to prove, that they play the role they have been meant for, i.e. to protect and secure friction junctions from wearing. The above analysis shows the similarity in the mechanism of friction junction boundary layer creation in case of applying conventional anti-wear additives (CAA) and EP's being a part of enriching additives of licensed oils and exploitation agents. The principle difference consists in their increased concentration, which affects the intensity of their interaction with rubbing surfaces, and therefore evokes the creation of a thicker (fig. 1.4b) and more resistant boundary layer, capable of withstanding greater dynamic and temperature friction junction loads. This has been confirmed through examinations [32 and other]. Group B of agents includes: agents containing substances of anisotropic coherence, i.e. of a layer structure, e.g. graphite, molybdenum or tungsten disulfide, nitrides sulfates and others; substances of a low internal coherence, e.g. soap, solid wax, vegetable fats, soft polymers (e.g. Teflon) and soft metals - copper, zinc, tin, lead, silver and other, usually in powder form. The most commonly used among anisotropic substances are graphite and molybdenum disulfide MoS2. The typical example of such an agent is Champion containing MoS2 as the main component along with another component, which activated by the heat generated on seizing metal cleanses them from oil decomposition products, thus making good sorption of MoS2 possible. As a result of physical adsorption and chemisorption evoked by the chemical reaction between sulfur ions and metal atoms a thin and very firmly bounded with the metallic surface is created. After this thin layer is created, recessions and cavities of roughness are filled with molecules of molybdenum disulfide until the moment when lost motion occurs between the molecules of MoS2. The created thin layer is characterized by good adsorption properties, therefore the oil molecules are strongly attracted and create a durable lubricating filter improving operating conditions of friction junctions thus improving its durability. 12

13 Materials like graphite or MoS2 have hexagonal structure with a distinct layer structure - fig. 1.5, 1.6. These materials are built from atom layers, which are strictly bound with each other whereas the bonds between layers are weak. The layered structure of crystalline netting occurs when net knots contain positive ions of small values and negative ions of high values that are easily polarized. Atoms arranged in a flat layer in these compounds are bound with each other by strong, covalent bonds, whereas the bonds between layers are of much weaker electrostatic type. Distinct slip planes and cleavage planes that run along particular layers characterize these bonds. Fig.1.5. Crystalline graphite netting [1] Fig.1.6. Crystalline netting of molybdenum disulfide MoS2 ; a) top view, b) bottom view [6] 13

14 The essence of lubrication with graphite (fig. 1.7) or with molybdenum disulfide (fig. 1.8) is explained by two theories: structural and adsorption theories. The structural theory attributes lubricative properties to the layered crystalline netting structure, whereas the adsorption theory - to the adhesion of the lubricant to the metal surface. It is right to assume that good lubricative properties are achieved when both conditions are fulfilled, i.e. the lubricating agent is of layer structure and possesses good adhesive properties. In meager lubricating conditions, when there is a possibility of direct contact of rough surfaces on both rubbing elements, the graphite molecules incorporated in the liquid lubricant are physically adsorbed on the metal surface thus creating a durable grafoidal film. The film then attracts graphite molecules until the surface is smooth and recessions in roughness are filled. The surfaces move mutually in the graphite layer along the so-called "graphite mirror". The created grafoid/graphite layer is characterized by good adsorption properties, and thanks to this oil molecules are strongly attracted and therefore create a sufficiently durable lubricating film, improving junction operation conditions thus increasing its durability [21, 26]. The mechanism of the lubricating function of molybdenum disulfide is similar to the mechanism of graphite lubrication. The difference is that the creation of the thin layer adhering directly with the metal surface occurs not only as a result of physical adsorption, but also as a result of chemisorption, evoked by chemical reaction between sulfur ions and metal atoms. After this thin layer is created the recessions of roughness are filled with molybdenum disulfide until the slip occurs between the layers of MoS2. Lubrication effects are similar as in case of graphite. Fig Diagram of friction junction lubricated by oil with the addition of graphite [27] 14

15 Fig Diagram of border layer in case of lubrication with molybdenum disulfide MoS2 The decrease of friction and wear of rubbing surfaces in boundary conditions is also possible through the creation of substitute lubricating film as an effect of introducing sub-microscopic ball teflon particles, e.g.: polytetrafluorethylene (PTFE) - lubricating agent with low level of inner coherence. The way PTFE agents function is different depending on the chemical structure as well as physical/chemical properties. From the behavior point of view of PTFE molecules on metal surfaces, two groups are distinguished [32]: PTFE molecules positively charged electrically in a permanent way; PTFE molecules electrically indifferent. The PTFE agents of type I are attracted to the metal layer thanks to the molecules as a result of the electrical charge and due to electrostatic interactions; a physical/chemical PTFE - metal bond is created. PTFE molecules adsorbed as thin layers on metal surfaces are generally of bigger dimensions than the micro roughness of these surfaces in boundary lubrication conditions. In the situation when the distance between rubbing surfaces is drastically diminished, e.g. in "tip to tip" placement of the roughness, the PTFE molecules are rolled out. The so-called luting of surfaces occurs. The created thin layers are characterized by a high degree of adherence and removal of the layers is only possible through grinding or sanding. PTFE in agents of type II has no ability to create layers characterized by durability similar to the one described above. The applied PTFE is electrically indifferent and therefore it has low adsorption on metal surfaces. These agents 15

16 periodically secure lubricating of rubbing micro surfaces (devoid of lubricating film layers) with a thin PTFE layer. Fig.1.9. The functioning principle of polytetrafluorethylene (PTFE) They play the role of ball bearings in friction junctions. Friction occurs in metal-teflon-metal connection (fig. 1.9). The properties of this type of agent define the way and effectiveness of its application for different kinds of machines and conditions of utilization: they are an addition to every portion of fresh lubricating agent introduced to tribological system as a refill or as its exchange. Metallic agents, e.g.: copper or lead introduced into the friction junction fill in the micro roughness like Teflon. As a result of mechanical interaction, the molecules the size of a few micrometers circulating in the junction along with the oil are crushed (fig. 1.10), they fill in the roughness and places where the oil filter is ruptured, the plating of rubbing surfaces occurs - fig The thin layer created in this way is firmly bound to the metallic surface due to adhesive interaction and is capable of resisting greater mechanical loads at a comparatively low friction factor similar to the factor characteristic for boundary or liquid friction. Open effect of Selective Transmission (ST) - group C of agents - has a special position in the development of new lubrication technologies. ST belongs to the group of technical solutions for friction junctions effectively decreasing unbeneficial results of friction. The ST effect is based on the tribological phenomenon that results in the creation of a thin, plastic, nonoxidizing layer having a specific structure. According to R. Marczak the phenomenon occurs when there is no liquid friction in given conditions in the rubbing pair, and in spite of this, the value of the friction factor and the 16

17 intensity of wear is by 2-3 orders of magnitude lower. This layer has been called "servolayer" - fig rings oil copper molecules pistons cylinder Fig Friction junction diagram with the use of soft metal-based agent (R2000) Fig Microphotograph of friction surface lubricated with SELEKTOL SPECJAL SD SAE 20W/40 modified with copper 17

18 Fig Microphotograph of servolayer created as a result of friction junction lubrication modification with metapolymer [10] Taking into consideration the essence of ST, the possibilities of utilization of the phenomenon in the construction and exploitation of machines have been presented in fig Fig Tribological system models ensuring ST realization: a, b, c, - with direct contact of Cu alloys (sinters) with the friction surface in the lubricating agent environment, d - lubricating agent containing copper or its compounds dispersion Cu organic compounds [25] 18

19 Literature research [4, 5, 23, 24] shows that there are two dominating hypotheses explaining the ST mechanism: the mechanism is based on micro adhesive tacking of soft metal molecules with the friction surface of hard metal. The protective layer being created has a soft metal structure in the preliminary stage. The composition may change in case favorable conditions for the ST process are created. The layer may become enriched in cathode components as a result of selective solution in e.g.: copper, when soft metals are its alloys. the mechanism according to which the creation of the metallic layer is a result of electrochemical processes such as: Me+n + ne Mo The layer being created contains only one metal introduced in the form of a metal plating additive into the lubricating agent or applied onto the friction surface as a result of the reaction of the lubricating substance components with the surface containing the metal - in the form of alloy components, covering or layers. In case of copper alloys and compounds - it is copper that is transmitted. On the current phenomenon recognition stage, it is known that ST occurs in specific input function intervals (P,v,T) in the presence of copper, in one of three slide friction junction elements and in properly active lubrication environment. The ST process is generally realized in the following stages: selective dissolution of copper components; the destruction of the above mentioned; the creation of colloidal molecules; weak electrostatic field formation and the transmission of colloids (copper ions) in this field; the inhibition process when s 1 µm. at even, equal covering of rubbing surfaces. To be able to realize the ST effect in metal pairs, it is necessary to apply lubricating agents enabling the formation of oxide layers on rubbing surfaces, as well as copper alloy components capable of electrochemical decomposition. The process of copper liberation and its transmission occurs as a result of lubricating agent s reaction with the metal surface. Copper and iron ions appear as a result of the connection of electrons, given up e.g.: by glycerol during the oxidizing process. The glycerol oxidizing products etch 19

20 the steel surface removing oxides. As a result of friction causing microplastic deformation and as a result of temperature increase, the copper crystallizes and attaches itself to the metal surface. At the same time the diffusion of copper ions into the steel surface purified from oxides takes place. A thin layer of copper well bound to the steel surface is obtained in this way. The decrease of the friction factor (friction between rubbing surfaces) as a result of the ST occurrence and the formation of easily deformed layers of copper consist in the realization of Kragielski's postulate. The characteristic feature of the ST phenomenon is making use of wear products in the realization of the anti-frictional layer. During the ST process, the wear products in reaction with lubricating agents create suspended matter, which decomposition results in the formation of an anti-frictional copper layer. The continuity of the process is ensured by constant creation and destruction of the suspended matter. 20

21 2. MODIFYING FRICTION JUNCTION OPERATING CONDITIONS WITH THE MOTOR LIFE PROFESSIONAL EXPLOITATION AGENT Industrial lubricating agents (oils) used in the lubrication of machines and device friction junctions should fulfill a number of functions, the most important of which are: lubrication; the oil should have the ability to create a firm oil film ensuring liquid lubrication as well as a boundary layer resistant to dynamic and temperature impact. Viscosity and lubricating ability are in this case essential; wear protection of the rubbing surfaces and seizure protection in extreme situations; cooling carrying away heat produced as a result of friction or fuel mixture combustion (in internal combustion engines) from the friction junction; corrosion protection chemical and electrochemical as the dominating in machine exploitation; carrying away impurities and wear products from friction junctions products of abrasive, chemical, corrosive wear and other kinds of wear; operating liquid with reference to oils operating in hydraulic systems, e.g.: pumps or hydraulic engines and other; other. The above-mentioned functions may be fulfilled thanks to the right package choice of enriching additives supplementing part of commercial oils. In the course of device operation, the oil is submitted to a number of factors that may more or less have a significant impact on its properties, including the loss of ability to fulfill the given task. The most important factors include: high temperature (thermal decomposition of molecules, carbonization, accelerated oxidizing); increased surface contact with air (accelerated oxidizing); very high pressures (high shearing forces - damaging the molecule structure); 21

22 infiltration of foreign matters (loss of lubricating ability, oxidizing catalysis processes); They cause the following harmful processes: contamination of oils by internal and external sources; loss of some properties as a result of additive "wearing"; loss of some physical/chemical properties. The above analysis shows that the oil should undergo certain diagnosis. Most generally, based on the stage of knowledge and technical development, the diagnosis of oil should be based on laboratory and exploitation tests. The oil condition diagnosis should be realized in two stages: stage one - oil production having proper technical/commercial requirements, conditioned by the application for lubrication of certain machines and devices (transmission, engine, hydraulic and other oils). stage two - oil diagnosis already in use and submitted to different, often unforeseen or non-identified loads. A full range of the above-mentioned tests always precedes the introduction of new oils into use. In case of the oil in use, the diagnosis is realized in a limited range due to diagnosis costs. That is also why research is conducted in order to solve the problem of efficient evaluation of current lubricating oil properties. Because there are no specific criteria of the boundary condition for oils, the research on this issue is based on the evaluation of kinetic changes in certain properties of the lubricating agent or in the search for a universal, integrated quality parameter. There are attempts to solve these problems in the following ways [34]: determination of most informative parameters, describing the condition of the lubricating agent and the condition of the lubricated object; determination of a border value of chosen oil parameter(s), characterizing the course of its deterioration; determination of oil operating time on the basis of condition similarity; border value specification of certain substance contents, determining the condition of the oil (e.g. the enriching additives). Most of these tests have not gone beyond the theoretical or laboratory stage. The Department of Decrement Treatment and Machine Exploitation Technology of the Technical University of Zielona Góra has conducted research on oil diagnosis for a number of years based on laboratory examination of physical/chemical oil properties. The laboratory examinations 22

23 have been backed up by tribological examinations that were verified in industrial conditions on certain technical objects. According to the authors, this trend in research makes the right evaluation of oil quality (including oils modified by exploitation agents) possible during the entire utilization process. The research has been conducted within a wide range of possible application of exploitation agents on the basis of chemical compounds, on the basis of soft metals, plastics as well as within the range of selective transmission. The present study presents the results of examinations concerning the modification of friction junction operating conditions with MOTOR LIFE exploitation agent. The research includes the lubricative properties, tribological properties, physical/chemical oil properties, the interaction of the agent on friction junction operating conditions during the process of machine cutting treatment, the noise emission and other. The MOTOR LIFE agent has also been used during the process of shaping the technological surface layer through burnishing OIL LUBRICATIVE PROPERTIES The properties of the lubricating agent that determines its ability of durable adhesion to rubbing surfaces are referred to as its lubricating ability. The lubricating ability is the ability of oil or plastic grease to create a layer characterized with a good mechanical durability in boundary friction conditions on the surface of metal. The lubricating ability of oil or grease depends on its chemical composition (lubricating additives) and the nature of the base. The increase of the lubricating ability of oils allows the reduction of the friction factor, it has an impact on rubbing surface wear reduction and protects them from seizure. The significance of the lubricating ability has a special meaning in conditions in which it is impossible to fully cover the rubbing surfaces with a thick layer of oil and to obtain liquid friction due to the high unit pressure, small speed or high temperature. In case of internal combustion engines the difficulties in reaching liquid friction conditions take place especially in the area of upper lower turning point of the piston in the cylinder, due to the loss of speed of the piston and the high temperature of cylinder walls in its upper parts. During the engine start-up, especially in winter conditions, the oil film is ruptured or very prone to be ruptured on operating surfaces of the cylinder and the bearing. The 23

24 lubricative properties of the oil determining the durability of the boundary layer are very significant in this case. According to PN-76/C (Examination of lubricative properties of oils and greases) the lubricative properties of lubricating agents are defined by indicators like: welding load Pz; wear under load factor Ih; highest load not causing seizure Pn; load causing seizure Pt. The tests are realized on a T-02 four-ball device (fig. 2.1), in which the friction junction consists of four steel balls immersed in the tested lubricating agent. The welding load (Pz) is the lowest given load that would (in established conditions) cause welding of the rotating ball with the three remaining fixed balls - which would show that the point of highest load possible to be transmitted by the lubricating layer was exceeded. Wear under load factor Ih is calculated based on the results of 10 runs carried out under consecutively applied loads preceding the welding load or partially carried out and partially taken from the table of norms. Highest load not causing seizure Pn is the highest applied load, which does not cause average d diameter defects higher than 5% of compensated ds diameter defects for each load read out from the norm. Load causing seizure Pt is the lowest load, which causes the distinct resistance increase in the friction junction (in established conditions) indicating that the lubricating layer was ruptured. The diameters of measured defects (wear and friction momentum) rapidly increase. The welding load Pz as well as the wear under load factor Ih characterizes the anti-seizure effect of lubricating agents. However, the highest load not causing seizure Pn and the load causing seizure Pt characterizes the lubricating layer durability and serves for defining conditions, in which the layer is damaged and seizure begins. It is right to define the following to be able to give a proper evaluation of lubricative properties of lubricating agents: 1 - what happens in the friction junction from the start-up moment to the moment of rupturing the lubricated layer; 2 - wear intensity from the moment of rupturing the lubricated layer to the moment of friction resistance stabilization; 3 - the regeneration ability of the lubricating layer. 24

25 This analysis suggested by A. Wachal [6] may be carried out on the basis of the diagram (fig. 1.2) - friction force in the time function. The diagram is obtained during examinations on the four-ball device. friction force Fig Four-ball device: a scheme, b friction junction; 1- engine, 2 prism, 3 lever, 4 weight, 5 moving ball, 6 fixed balls [1] wear phase I boundary layer damage phase II wear phase III friction resistance stabilization time Fig Friction force impact in time function (operating time of friction junction four-ball device) 25

26 As it results from fig. 2.2, the friction force diagram in the function of time (load) can be divided into three phases: phase I - boundary layer damage. The criteria of this phase are: boundary layer durability - time t - from the start-up moment to the beginning of rapid friction force increase, which indicates the boundary layer rupture; boundary layer durability Wwg(friction force ordinate value at the moment of rupture). Taking into account that ruptures of the boundary layer occur on micro-surfaces, the friction force is bigger if the rate of micro roughness where the boundary layer is ruptured is bigger. The more resistant the boundary layer, the lower the friction force is at the moment of rupture; phase II - boundary layer damage, i.e.: wear of operating elements. The evaluation criteria of this phase are: work put in for wear Z characterized by the area under the curve outlining the force peak; boundary layer regeneration ability, characterized by the time of return to friction in settled conditions tr and an average friction force at the time of wear phase; phase III - Friction resistance stabilization, i.e. stabilization of friction resistance on Tr level. Due to the increase of friction surface and thus the decrease of unitary pressure, conditions for creation of friction junction operating within the range of boundary friction or even hydrodynamic friction are created. High suitability degree of this evaluation method of lubricative properties has been confirmed by research concerning the modification impact of tested MOTOR LIFE oils on the behavior of the lubricating substance in boundary friction conditions. It has also been proved that this evaluation method is suitable for plastic greases. Chart 2.1 shows the lubricative properties of some lubricating agents oils used most often, including those modified by the MOTOR LIFE exploitation agent. Fig show the graphical illustration of lubricative properties examination results. Machine oils AN are used to lubricate lightly loaded parts of industrial machines (bearings, slide bearings, mechanical transmissions, spindles, etc.) and auxiliary friction junctions. The AN-68 machine oil lubricative properties and the properties of the oil modified with the exploitation agent is shown in chart 2.1 and fig

27 Chart 2.1. The results of lubricative properties of commercial oils and oils modified with the MOTOR LIFE exploitation agent LUBRICATIVE PROPERTIES [dan] Lubricating composition Machine oil AN-68 Turbine oil TU-32 Hydraulic oil HL-32 Transmission oil Hipol 15 Compressor oil SP-10 Super Uniwersal CE/SF 15W/40 ParusGl4 80W/90 Lubinol 80L Castrol EPX90 Castrol GTX 5W-40 mag. Elf Sup.sport 0W-40 Renolin MRVG-4 Transol 100 Shell Tellus -68 ŁT43 ŁT-4S3 MOTOR LIFE 3 MOTOR LIFE6 MOTOR LIFE 7 Commercial oil Commercial oil + 5% MOTOR LIFE Pz Ih Pn Pt Pz Ih Pn Pt s. plastic s. plastic s. plastic s. plastic s. plastic white bearing bearing bearing for joints with MoS2 for chains 27

28 As research shows, a distinct improvement of lubricative properties has been observed with oil modified with the MOTOR LIFE agent. Welding load Pz has increased by 150%, the wear under load factor Ih - by 72%, highest load not causing seizure Pn by 46.5% and load causing seizure by 65.9%. This means that the effect of oil modification with the MOTOR LIFE agent, the anti-seizure function of oil has been improved and the durability of the lubricating layer (and the boundary layer in particular) has increased. The results of friction force variations examinations for the given load of P = 160 dan (fig. 2.4) as well as for the growing load (fig. 2.5) are the confirmation of the above statement. Fig. 2.4 shows that the friction force value has been very distinctly lowered as a result of modification as compared to pure oil. The growing load of the friction junction has caused the welding of friction junction in case of pure oil application in a time of ~10 sec. In case of modified oil the level of friction force is much lower and welding has not occurred, which shows the increase of boundary layer durability, resistant to the action of higher loads and temperature. 400 Pz 350 Ih friction force [dan] 300 Pn 250 Pt AN 68 AN 68 + Motor Life Fig AN-68 machine oil lubricative properties and oil modified with the MOTOR LIFE exploitation agent 28

29 8,0 AN68 AN68+Motor LIFE friction force [dan] 7,0 6,0 5,0 4,0 3,0 2,0 1,0 0,0 0,8 1,6 2,4 3,2 4,0 4,8 5,7 6,6 7,4 8,1 8,9 9,7 10,6 time [s] Fig The course of friction force variability for a constant given load of P = 160 dan lubricated with AN-68 oil and oil modified with the MOTOR LIFE exploitation agent 7,0 AN68 AN68+Motor LIFE friction force [dan] 6,0 5,0 4,0 3,0 2,0 1,0 0,0 0,8 2,5 4,1 5,7 7,4 9,1 10,7 12,3 13,9 15,6 17,2 time [s] Fig The course of friction force variability for the growing load of the friction junction lubricated with AN-68 oil and oil modified with the MOTOR LIFE exploitation agent 29

30 TU turbine oils are mainly applied as lubricating agents for steam, gas and water turbines. They are also used as hydraulic liquids in turbine regulation systems. TU turbine oils can also be applied for lubrication of other devices that need the use of oils possessing turbine oil quality with enriching additives. TU turbine oils should not be used with devices requiring oils with special anti-wear properties, because they do not contain EA additives. The graphical illustration of lubricating abilities of the TU-32 turbine oil and the same oil modified with the MOTOR LIFE exploitation agent is presented in fig Fig. 2.6 shows that all indicators defining lubricating abilities have improved as a result of turbine oil modification with the MOTOR LIFE agent. The welding load Pz has increased from dan, the maximal load not causing seizure Pn from dan, the wear under load factor Ih from dan and the load causing seizure Pt from dan. The above shows clearly that the MOTOR LIFE agent has an impact on improvement of anti-seizure properties of the tested oil and on the durability of the boundary layer. Fig. 2.7 shows that the constant load P = 126 dan on the friction junction, after ~0.5 sec causes the rapid growth of friction force. The force then remains at the same high level. The friction resistance is quite different for the modified oil. The junction operates up to ~1.5 sec in boundary friction conditions, then the rupture of the boundary layer occurs - the friction force increases only up to 50% of the analogical value defined for pure oil, then it drops and after ~4 sec is stabilized on the entry level. The confirmation of the positive impact of the modification is the course of variations of the friction force for variable, growing load in the time function fig In case of pure oil, the rupture of the boundary layer occurred after ~3 sec, and after ~ 9 sec welding occurred. In case of the modified oil, the rupture occurred after ~ 9 sec. Further loads have not caused seizure (welding) of the friction junction L-HL hydraulic oils are obtained from mineral oils of improved anticorrosion properties, anti-oxidizing properties and characterized by a medium level of anti-wear properties. Oils of this sort are used in medium-loaded power transmission systems and hydraulic control systems. Lubricative properties of HL-32 hydraulic oil have been presented in Fig As chart 2.1 and fig. 2.9 show, the HL-32 hydraulic oil is characterized by average lubricative properties. The modification of the oil with the MOTOR LIFE exploitation agent evidently improves its lubricating abilities. As a result of modification, all lubricative properties improve welding load Pz from dan, load not causing seizure Pn from 80 30

31 100 dan, wear under load factor Ih from dan, and load causing seizure Pt from dan. With the given load P = 160 dan matching the welding load (fig. 2.10), the friction junction operates in boundary friction conditions in the modified oil for up to ~ 6 sec, then it grows until it reaches the level of ~3.2 dan and remains at this level, which is more than twice lower than the maximal friction force of the pure oil. The course of friction force variability for growing load on the friction junction fig is the confirmation of the favorable effects of oil modification. In case of the modified oil, the friction force drops after ~ 2 sec and remains at a very low level. friction force [dan] 350 Pz 300 Sn 250 Pn 200 Pt TU32 TU32+MOTOR LIFE lubricating agents Fig Lubricative properties of TU-32 turbine oil modified with the MOTOR LIFE exploitation agent 31

32 4,5 4,0 friction force [dan] 3,5 3,0 TU32 2,5 TU32+MOTOR LIFE 2,0 1,5 1,0 0,5 0, time [s] Fig The variability course of friction force for a constant load of P = 126 dan in case of the friction junction lubricated with TU-32 turbine oil and the same oil modified with the MOTOR LIFE exploitation agent 9,0 friction force [dan] 8,0 7,0 6,0 TU32 5,0 TU32+MOTOR LIFE 4,0 3,0 2,0 1,0 0, time [s] Fig The variability course of friction junction friction force for the growing load in case of friction junction lubricated with TU-32 turbine oil and the same oil modified with the MOTOR LIFE exploitation agent 32

33 Pz Ih Pn Pt 300 friction force [dan] HL 32 HL32 + Motor Life Fig The HL-32 hydraulic oil lubricative properties and the properties of the same oil modified with the MOTOR LIFE exploitation agent 8,0 Friction force [dan] 7,0 HL32 HL32+MOTOR LIFE 6,0 5,0 4,0 3,0 2,0 1,0 0,0 0,0 2,0 4,0 6,0 8,0 10,0 12,0 time [s] Fig The variability course of friction force in case of applying a constant load of P = 160 dan on the friction junction lubricated with HL-32 hydraulic oil and the same oil modified with the MOTOR LIFE exploitation agent 33

34 Fig The course of friction force variability for the growing load of the friction junction lubricated with HL 32 hydraulic oil and the oil modified with the MOTOR LIFE exploitation agent Transmission oils like HIPOL are applied for vehicle transmissions. They are obtained from crude oil treatment and contain additives improving lubricative properties and foaming resistance as well as containing antioxidizing and anti-corrosion additives. HIPOL oils for vehicle transmissions are applied for lubricating mechanical vehicles transmissions operating in heavy conditions, i.e. at high speeds and low torque or low speeds and high torque. Fig show the results of HIPOL 15 transmission oil lubricative properties. As the tests show, the oil is characterized with good lubricative properties thanks to lubricating additives. Modification with the MOTOR LIFE exploitation agent increases its lubricative properties (chart 2.1); the welding load Pz increases, as well as wear under load factor Ih, the load not causing seizure Ih and load causing seizure Pt. 34

35 Lubricative properties [ dan] Pz 150 Ih 100 Pn Pt 50 0 HIPOL15 HIPOL 15+MOTOR LIFE Lubricating agents friction force [dan] Fig HIPOL 15 transmission oil properties and properties of the oil modified with the MOTOR LIFE exploitation agent 5,0 4,5 4,0 3,5 3,0 2,5 2,0 1,5 1,0 0,5 0,0 Hipol+MOTOR LIFE Hipol 0,8 1,6 2,3 3,1 3,9 4,6 5,4 time [s] 6,2 7,1 7,8 8,6 9,4 10,2 Fig The variability course of friction force for a constant load of P = 250 dan on the friction junction lubricated with transmission oil and the oil modified with the MOTOR LIFE exploitation agent 35

36 Friction force [dan] HIPOL HIPOL15+MOTOR LIFE time [s] The variability course of friction force for a growing load of P = 250 dan on the friction junction lubricated with transmission oil and the oil modified with the MOTOR LIFE exploitation agent SP compressor oils are used for lubricating one level and multilevel air compressors of different types, not heating the oil over 150 o Celsius and the construction of which allows the use of oils with no enriching additives. They can also be used for air blowers. The lubricative properties of SP 10 compressor oil including the case of modification with MOTOR LIFE have been presented in chart 2.1 and fig The research shows that SP 10 compressor oil is characterized with very weak lubricative properties. As a result of modification with the MOTOR LIFE exploitation agent, the lubricating indicators improve, and in particular the welding load Pz, and load causing seizure Pt. The tested load of P = 160 dan (fig. 2.16) in case of pure oil the friction force increases in the function of friction junction operating time to achieve the value of ~ 4.5 dan in the final stage. In case of the modified oil the friction force remains at the level of ~ 1 dan. In the time interval from W ~ 2.3 to 4 sec a slight increase of friction force occurs (boundary layer rupture) and then the operating conditions stabilize at the starting level. The course of variability of friction force in function of growing load (fig. 2.17) is the confirmation of very favorable impact of the MOTOR LIFE agent. As it the illustration shows, the rupture of the boundary layer occurred after ~ 3 sec and welding of friction junction elements occurred after ~ 9 sec in case of pure oil. Whereas in case of modified oil, the rupture of the boundary layer occurred after ~ 7 sec and the welding did not take place. The friction force in the final stage reached the value of ~ 2 dan. 36

37 lubricative properties [dan] 700 Pz 600 Sn 500 Pn 400 Pt SP10 SP10+Motor Life lubricating agents Fig Lubricative properties of SP 10 compressor oil and the same oil modified with the MOTOR LIFE exploitation agent 6,000 friction force [dan] 5,000 4,000 SP10 3,000 SP10+MOTOR LIFE 2,000 1,000 0,000 0,000 2,000 4,000 6,000 8,000 10,000 12,000 time [s] Fig The friction force variability course in case of a constant load of P = 126 kg on the friction junction lubricated with SP 10 compressor oil and the same oil modified with the MOTOR LIFE exploitation agent 37

38 friction force [dan] 8,0 7,0 SP10 6,0 SP+ MOTOR LIFE 5,0 4,0 3,0 2,0 1,0 0,0 0,0 5,0 10,0 15,0 20,0 time [s] Fig The friction force variability course in case of the growing load on the friction junction lubricated with SP 10 compressor oil and the same oil modified with the MOTOR LIFE exploitation agent Elf Super Sport 0W-40 engine oil 100% synthetic engine oil applicable for: the newest generation of petrol (also propane-butane) engines and diesel engines (including those with direct fuel injection) used in passenger vehicles; also recommended for turbocharged engines; during strong frost and very high temperatures; for normal, sport and high performance driving. The examination results shown on chart 2.1 and demonstrate that Elf Super Sport 0W-40 engine oil is characterized with very good lubricative properties. The modification of this (synthetic) oil with the MOTOR LIFE agent considerably improves its lubricative properties within the range of anti-friction properties (a very distinct increase of PZ and Ih indicators) as well as the durability of the boundary layer (Pn and Pt indicators). Fig shows that the load of force P = 250 dan (value equal to welding load in case of pure oil) on the friction junction, the maximal friction force is higher than in case of the modified oil. In case of the modified oil, after the period of intensive wear, the stabilization of friction force occurs in time of ~3.5 sec on the level of ~1 dan. The durability of the boundary layer is increases by approximately 30% - fig

39 400 Pz lubricative properties[dan] 350 Ih Pn 200 Pt Elf Super Sport 0W /40 Elf Super Sport 0W /40 + Motor Life friction force [dan] Fig Lubricative properties of Elf Super Sport 0W-40 engine oil and the same oil modified with the MOTOR LIFE exploitation agent 6,000 Elf 0W 40 5,000 Elf 0W 40 + Motor Life 4,000 3,000 2,000 1,000 0,000 0,72 1,50 2,33 3,11 3,94 4,72 5,50 6,33 time [s] 7,11 7,89 8,78 9,61 10,39 Fig The friction force variability course for a constant load force of P = 250 dan on friction junction lubricated with Elf Super Sport 0W-40 engine oil and the same oil modified with the MOTOR LIFE exploitation agent 39

40 7 Elf 0W 40 Elf 0W 40 + Motor Life friction force [dan] ,8 2,4 4,0 5,6 7,1 8,8 10,4 12,0 13,6 15,1 16,9 time [s] Fig The friction force variability course for the growing load force on the friction junction lubricated with Elf Super Sport 0W-40 engine oil and the same oil modified with the MOTOR LIFE exploitation agent Castrol GTX 5W-40 magnatec engine oil is a synthetic oil characterized with a low degree of viscosity. It contains a polarized synthetic ester that adheres very firmly to the rubbing surfaces of the engine. A protective layer is created this way and remains on the inner surface of the engine even after the engine is stopped and it does not drift overnight. It is used in new and old engines, running on petrol and gasoline, in turbocharged engines and those with fuel injection. The lubricative properties of Castrol GTX 5W-40 magnatec were presented in fig Fig shows that the lubricative properties of the oil have improved as a result of modification of this synthetic oil with the MOTOR LIFE agent. It concerns properties within the range of anti-seizure properties - the increase of welding load from 315 up to 500 dan, the wear under load factor Ih - from 48.4 to dan (tab.2.1), and although slightly also within the range of the boundary layer durability - the increase of load causing seizure Pt from to dan, at a constant load causing a seizure of Pn = 100 dan (chart.5.1) The examinations results shown in fig and 2.23 showing the friction force variability for the constant load of P = 315 dan (value equal to welding load) fig and the load increasing in time are the confirmation of 40

41 favorable impact of the MOTOR LIFE agent on Castrol GTX 5W-40 magnatec oil. As it results from fig the maximal friction force level for pure oil is higher than in case of the modified oil. In case of the pure oil the welding of friction junction occurred in t 3.7 sec. In case of oil modified after the period of intensive wear the stabilization of friction force (movement resistance) at a level of approximately 2 dan was observed after 3 sec. In case of the growing load (fig. 2.23) the increase of boundary layer durability is distinct. The confirmation of this is the increase of load causing seizure Pt by approximately 1 dan. In case of pure oil the seizure occurred in t 9.5 sec whereas in case of the modified oil the stabilization of friction force on the level of approximately 2daN was observed after approximately 11.5 sec. Castrol EPX 90 transmission oil is a modern transmission oil recommended also for conic transmissions. It is enriched with additives improving its resistance against the transmission of high loads (EA). The oil can be applied for all mechanical gear transmissions, main transmissions demanding transmission oil according to API GL-5. The lubricative properties of Castrol EPX 90 transmission oil were presented in chart.2.1 and in fig The conducted research shows that Castrol EPX oil is a very good brand protecting friction junction from wears and minimizing movement resistance. The modification of this oil with the MOTOR LIFE agent improves its lubricative properties. Indicators like: welding load (Pz = 620 dan) and load not causing seizure (Pn = 126 dan) do not change. The two remaining indicators do change: wear under load factor Ih increases from up to dan and the load causing seizure Pt increases from to dan. The favorable impact of the MOTOR LIFE agent on lubricative properties of Castrol EPX 90 is also visible in course of registration of friction force for increasing load - fig The illustration shows that the rupture of the boundary layer in case of pure oil occurred after approximately 6.5 sec and after approximately 7.5 sec in case of the modified oil. 41

42 friction force [dan] Pz Ih Pn Pt CASTROL GTX MAGNATEC 5W/40 CASTROL MAGNATEC GTX 5W/40 + MOTOR LIFE lubricat ing agent s Fig Lubricative properties of Castrol GTX 5W-40 magnatec engine oil and the same oil modified with the MOTOR LIFE exploitation agent 7,000 Castrol GTX 5W-40 Castrol GTX 5W-40+Motor Life friction force [dan] 6,000 5,000 4,000 3,000 2,000 1, , 8, , ,3 time [s] 7, , , , , , , , 0, ,000 Fig The friction force variability course for a constant load force of P = 315 dan on the friction junction lubricated with Castrol GTX 5W-40 magnatec engine oil and oil modified with the MOTOR LIFE exploitation agent 42

43 7,0 Castrol GTX 5W -40 Castrol GTX 5W -40+Motor Life 6,0 friction force[dan] 5,0 4,0 3,0 2,0 1,0 0,0 0,83 2,33 3,89 5,39 7,00 8,61 10,17 11,83 13,44 14,94 16,56 time [s] friction force [dan] Fig The friction force variability course for the growing load on the friction junction lubricated with Castrol GTX 5W-40 magnatec engine oil and oil modified with the MOTOR LIFE exploitation agent Pz Ih Pn Pt CASTROL EPX 90 CASTROL EPX 90 + MOTOR LIFE lubricat ing agent s Fig Lubricative properties of Castrol EPX 90 transmission oil and the same oil modified with the MOTOR LIFE exploitation agent 43

44 friction force[dan] 6,0 Castrol EP X 90 Castrol EP X 90+Motor Life 5,0 4,0 3,0 2,0 1,0 0,0 0,8 1,6 2,3 3,2 3,9 4,7 5,6 6,3 7,1 7,8 8,6 9,4 10,2 time [s] Fig The friction force variability course for a constant load force of P = 620 dan on the friction junction lubricated with Castrol EPX 90 transmission oil and the same oil modified with the MOTOR LIFE exploitation agent 6,0 Castrol EP X 90 Castrol EP X 90+Motor Life friction force [dan] 5,0 4,0 3,0 2,0 1,0 0, time [s] Fig The friction force variability course for the growing load on the friction junction lubricated with Castrol EPX 90 transmission oil and the same oil modified with the MOTOR LIFE exploitation agent 44

45 2.2. PLASTIC GREASE LUBRICATIVE PROPERTIES Plastic greases are complex colloidal configurations, consisting of a dissipating (dispersing) phase, and a dissipated (dispersed) phase and enriching additives. They compose approximately 10% of the total amount of lubricating agents. Plastic greases are most widely used where periodical lubrication is necessary or in case it is not recommended or not possible to use other lubricating agents due to the construction or nature of operation of a given friction junction. In principle they are used to decrease friction resistance, they protect from corrosion, they secure elements of machinery during long storage periods and for other special situations. The functions fulfilled by plastic greases depend on the grease type. The most commonly used are anti-frictional greases protecting surfaces from dry friction, they even up roughness (limitation of surface pressure), they seal lubricated junctions, they protect lubricated surfaces against corrosion, limit vibrations and noise produced during the lubricating junction operation. The anti-frictional greases include, among others, the bearing greases that are most often used in industrial practice. The greases include LT plastic greases commonly used and multi-functional LT-4S greases. LT plastic greases commonly used for rolling bearings are products obtained from thickening of refined mineral oils with soaps containing the addition of inhibitors. Depending on the type of used soaps and on the class of consistency, the following types of commonly used LT plastic greases are distinguished [8]: LT 12 grease - thickened with calcium soaps with consistency class 2 (operating temperature range from -20 to 50oC); LT 23 grease - thickened with sodium and calcium soaps with consistency class 3 (operating temperature range from -30 to 70oC); LT 41 grease - thickened with lithium and calcium soaps with consistency class 1 (operating temperature range from -30 to 120oC); LT 42 grease - thickened with lithium and calcium soaps with consistency class 2 (operating temperature range from -30 to 120oC); LT 43 grease - thickened with lithium and calcium soaps with consistency class 3 (operating temperature range from -30 to 120oC. The use of LT 41, LT 42, and LT 43 greases depend on the method of supplying grease into the bearing (central lubrication or manual lubrication), the rotational speed and bearing operating temperature. 45

46 LT-4S greases are high class, modern lithium greases on the basis of lithium hydroxystearate and selected mineral oils: they contain lithium soaps of multi molecule fatty acids, additives improving lubricative properties as well as anti-corrosion and anti oxidization additives. They are water resistant. Depending on the consistency class, two sorts of LT-4S greases are produced: LT-4S2 grease with consistency class 2; LT-4S3 grease with consistency class 3. Plastic multifunctional greases LT-4S are used for rolling bearing lubrication (including vehicle bearings) operating in conditions demanding high mechanical stability, deterioration resistance and anti-corrosion properties of the grease, in a temperature range from approximately 30oC up to approximately 130oC. The lowest and the highest application temperature depend on the consistency class of the grease, bearing driving momentum, the size and rotational speed of the bearing. LT-4S2 and LT-4S3 greases are used depending on the bearing size (lubricated centrally or manually), rotational speed and bearing operating temperature. The fig and chart 2.1 present comparative tests results of lubricative properties of commonly used plastic greases LT 43 and LT 4S3. The test results were compared to the new MOTOR LIFE 3 plastic bearing grease. Tests have shown that the MOTOR LIFE 3 plastic grease is characterized with distinctly better lubricative properties when compared to LT 43 and LT 4S3 greases. Within the range of anti-seizure values, the welding load Pz is equal to 400 dan for MOTOR LIFE, 160 dan for LT 43 and 200 san for LT 4S3; the wear under load factor Ih equals correspondingly: MOTOR LIFE dan, LT daN, LT 4S dan. MOTOR LIFE plastic grease is characterized by much greater durability of the boundary layer when compared to other tested kinds, which is clearly confirmed by the values of indicators values of the load not causing seizure Pn and the load causing seizure Pt (shown on chart 2.1. and fig. 2.29). As it results from the fig illustrating the course of friction force variability in function of the growing load, the rupture of the boundary layer for LT 43 grease occurred after 3.5 sec, in case of LT 4S3 after 4.7 sec and after 8.8 sec in case of MOTOR LIFE. If we assume that the load growth in the time function is N/sec, the rupture of the boundary layer for LT 43 grease occurred under the load of 1429 N, under the load of 1926 N for Lt4S3 and in case of MOTOR LIFE 3 it occurred at the load value of

47 N. This means that the application of MOTOR LIFE 3 grease considerably and unequivocally improves lubricative properties of friction junction, which is able to transmit much greater loads and temperatures in identical exploitation conditions as compared to other tested plastic greases. 400 lubricating properties [dan] ŁT-43 ŁT-4S3 MOTOR LIFE 3 Fig Lubricative properties of lubricating and bearing greases Friction force[dan 3,0 2,5 2,0 1,5 1,0 0,5 0,0 0,8 1,6 2,3 3,1 3,9 4,7 5,6 6,3 7,2 8,0 8,8 9,7 10,4 time [s] MOTOR LIFE 3 ŁT4S3 Fig The friction force variability for plastic bearing greases for an applied load of P = 160 dan 47

48 Friction force[dan] 9,0 8,0 ŁT4S3 7,0 ŁT43 6,0 MOTOR LIFE 3 5,0 4,0 3,0 2,0 1,0 0 0,0 2,0 4,0 6,0 8,0 10,0 12,0 14,0 16,0 18,0 20,0 time [s] Fig The friction force variability for plastic bearing greases for growing load 48

49 2.3. EVALUATING CHANGES OF SELECT PROPERTIES OF CE/SF SAE 15W/40 ENGINE OIL IN THE PROCESS OF EXPLOITATION Oil is one of the tribological system elements. In the engine, the tribological elements of friction junctions include: slide bearings (pivot, plane bearing) and sleeve piston/rings. Their proper functioning determines the technical efficiency of the engine the economical and ecological exploitation issues. The basic functions of oil engine are: reduction of movement resistance between rubbing surfaces of rubbing elements by the creation of a proper lubricating layer (not allowing dry friction) between them; prevention against excessive wear of rubbing elements and seizure in extreme conditions; cleaning the engine removing the precipitations in order to ensure minimal ease in collecting heat from these surfaces and normal functioning of the engine; fulfilling the role of a cooling liquid transmission of heat produced in the friction junction (heat produced as a result of burning); carrying away impurities and products of friction junction wear; reducing the power loss to a minimum (avoiding the creation of excessive hydraulical resistance when pressing oil); sealing backlashes in lubricated connections; amortization of dynamic loads of engine elements; protection of the engine against corrosive action of combustion gas and the surrounding atmosphere. The tasks enumerated above can be fulfilled only when the engine contains a proper package of enriching additives (viscosity, pressure controllers, anticorrosion, anti-oxidizing, washing and dissipative, lubricating and others). The properties of the engine oil change during the course of its exploitation, until the moment when they totally lose the ability to fulfill given functions. The most important factors affecting oil deterioration are [20]: Appearance of high temperature causing thermal decomposition of molecules, carbonization and accelerated oxidization; High cutting forces caused by very high loads, damaging molecule structure; 49

50 Increased surface contact with air accelerated oxidization; Infiltration of foreign matters (loss of lubricating ability, oxidization catalysis processes). This causes changes (most often worsening) of functional properties of the oil. Taking into consideration the possibility of friction junction operating condition modification in car engines, a study was launched on the impact of the MOTOR LIFE exploitation agent and on the changes it causes in CE/SF SAE 15W/40 engine oil properties during the course of its exploitation. The following criteria of the oil condition were taken into account: lubricative properties defined by following indicators: welding load Pz, wear under load factor Ih, highest load not causing seizure Pn and the load causing seizure Pt determined by a computerized fourball device (T-02 tester produced by ITE in Radom); change of kinematical viscosity and alkalinity number; iron contents in oil. In the course of tests, in parallel with the diagnosis of the oil condition were pressure in cylinders, starting current and smokiness controlled. The tests were run on SW-400 engines mounted in AUTOSAN buses within the mileage range of up to 20,000 km, which corresponded with the oil change period. The test results on lubricative properties of the CE/SF SAE 15W/40 engine oil modified with exploitation agent within the range of mileage up to 20,000 km (oil change period) were presented on chart 2.3 and fig The tests results show that the welding load Pz is not changeable within the whole range of the bus s mileage, however other indicators are subject to change. It concerns the indicators defining the lubricating abilities, i.e.: the wear under load factor Ih, the highest load not causing seizure Pn and load causing seizure Pt. It is characteristic, that the biggest loss of lubricative properties occurs during the first exploitation phase i.e. up to ~5,000 km. Within the range between 5,000 20,000 km the lubricative properties remain on a similar level and in case of bus mileage of ~20,000 km, there is improvement in lubricative properties as compared to the mileage of ~15,000 km. The conclusion should be that such a course of variability in lubricative properties of the modified oil is the result of: the presence of large quantities of consumed oil (~ 1 liter) remaining in the engine after oil change; modification of lubricative properties with the MOTOR LIFE exploitation agent. 50

51 The first oil exploitation period and worsening of its lubricative properties is the result of intermixing of fresh oil with old oil. The old oil remaining in the engine contains filings of metals cumulated in oil passages, oil pump and oil sump, wear products (sodium, iron, silicon, copper and others, which was proved by research). A conclusion should arise that the slight decrease of lubricative properties of the oil within the range between 5,000 20,000 km is caused by the impact of the MOTOR LIFE agent the creation of an additional substitute boundary layer [19], which was also confirmed by comparative tests of friction force for constant and growing loads performed for pure engine oil and the modified oil with the MOTOR LIFE agent fig and As fig shows that in case of pure oil the friction load force of P = 315 dan causes seizure and modified oil with the agent causes the restoration of operating conditions within the range of boundary lubrication after the period of intensive wear. In case of the growing load (fig. 2.32) the modified oil is characterized with better lubricative properties, and what s most important, the durability of its boundary layer increases in case of pure oil, its rupture occurs after approximately 5.3 seconds, whereas in case of modified oil after approximately 6.3 sec. Chart 2.3. Lubricative properties of CE/SF SAE 15W/40 engine oil modified with the MOTOR LIFE exploitation agent within the bus mileage range of up to 20,000 km Bus mileage [km] 0 ~500 ~5,000 ~10,000 ~15,000 ~20,000 Pz Lubricative properties [dan] Pn Ih Pt Effective impact of the MOTOR LIFE exploitation agent on lubricative properties of the tested oil is confirmed by tests carried out after a bus mileage of approximately 20,000 km fig.2.33 and 2.34 smaller friction forces and greater boundary layer durability. The favorable impact of the MOTOR LIFE exploitation agent has been confirmed by smaller diameters of defects chart 51

52 2.4 and fig It is characteristic in this case that the wear of balls is considerably lower in case of the modified oil than in comparison to the wear with the use of pure oil, both before the exploitation and after the process of exploitation corresponding to bus mileage of ~ 20,000 kilometers. 500 Lubrica tive properties [dan] 450 Pz 400 Pn 350 Ih 300 Pt bus m ileage [km ] Fig Lubricative properties of CE/SF SAE 15W/40 oil modified with the MOTOR LIFE exploitation agent within the bus mileage of up to ~20,000 km 8,0 friction force [dan] 7,0 6,0 CE/SF... 5,0 CE/SF... + MOTOR LIFE 4,0 3,0 2,0 1,0 0,0 0,8 1,6 2,3 3,2 4,1 4,8 5,6 6,3 7,1 7,7 8,5 9,3 10,1 time [s] Fig The friction junction force variability course at a load of P=315 dan (on the friction junction lubricated with CE/SF SAE 15W/40 engine oil and modified oil with the MOTOR LIFE exploitation agent) 52

53 CE/SF... CE/SF... + MOTOR LIFE 5,0 4,0 3,0 2,0 9, 8 10,6 11,4 12,2 12,9 13,7 14,4 15,2 15,9 16,7 17,4 9, 1 8, 2 7, 5 6, 8 6, 0 5, 3 4, 4 3, 7 2, 9 2, 2 1, 5 1,0 0,0 0, 8 friction fo rce [dan] 7,0 6,0 t im e [s] Fig The friction force variability course for variable (growing) load on the friction junction lubricated with CE/SF SAE 15W/40 engine oil and modified oil with the MOTOR LIFE exploitation agent friction force [dan] 8,0 7,0 6,0 5,0 4,0 3,0 2,0 1,0 0,0 CE/SF... CE/SF... + MOTOR LIFE 0,8 1,7 2,5 3,3 4,2 4,9 5,8 6,6 7,4 8,2 8,9 9,7 10,5 t im e [s] Fig The friction force variability course at a load force of P=315 dan on the friction junction lubricated with CE/SF SAE 15W/40 engine oil and modified oil with the MOTOR LIFE exploitation agent after a bus mileage of ~20,000 km 53

54 CE/SF... friction force [kg] 6,0 CE/SF... + MOTOR LIFE 5,0 4,0 3,0 2,0 1,0 0,0 0,8 2,3 4,1 5,8 7,3 8,9 10,8 12,5 14,1 15,8 17,4 time [s] Fig The friction force variability course for variable (growing) load of the friction junction for the CE/SF SAE 15W/40 engine oil and modified oil with the MOTOR LIFE exploitation agent after a bus mileage of ~20,000 km The favorable impact of the agent on the engine operation consists of the decrease in movement resistance, especially in the stage of engine start-up the decline in start-up current from 240 to 220 A (chart 2.4) and cylinder pressure within the range of 1 do 1.5 atmospheres (chart 2.4, fig. 2.36). Fig as well as fig and 2.39 expresses the confirmation of the engine friction junctions operating conditions resulting from oil modification. The oil modification also had an impact on the decrease in fume pollution lower smokiness level chart 2.4, fig Laboratory tests of chosen physical/chemical oil properties, i.e. kinematical viscosity in temperatures of 40oC and 100oC as well as base number have shown that the modification of CE/SF SAE 15W/40 engine oil with the MOTOR LIFE agent does not have an impact on changes of these properties chart 2.5 and fig The picture illustrating the variability of pollution taking place during the exploitation course of tested modified oil with the MOTOR LIFE agent has been shown in fig The coloration (darkening of the oil already after the mileage of ~500 km) is very characteristic. It is the result of intermixing of old oil remaining in the engine after oil change (0.7 1l) with fresh oil having a full package of enriched additives that have impact on the impurities and wear products. 54

55 Chart 2.4. Diameter defects after testing lubricative properties of CE/SF SAE 15W/40 pure engine oil and modified oil with the MOTOR LIFE exploitation agent both before and after the bus mileage equaling ~20,000 km Diameter defect [mm] Load on friction junction [dan] Z z z Lubricating agent type CE/SF SAE 15W/40 CE/SF SAE 15W/40 after 20,000km CE/SF SAE 15W/40 + MOTOR LIFE CE/SF SAE 15W/40 + MOTOR LIFE after 20,000 km z diameter defects [mm] 3,5 3 2,5 2 1,5 1 0, load applied [dan] CE/SF SAE 15W/40 CE/SF SAE 15W /40 after km CE/SF SAE 15W/40 + MOTOR LIFE CE/SF SAE 15W /40 + MOTOR LIFE after km Fig Diameter defects after testing lubricative properties of CE/SF SAE 15W/40 engine oil pure and modified with the MOTOR LIFE exploitation agent both before and after bus mileage equaling ~20,000 km 55

56 Chart 2.5. Test results of the SW-400 engine technical parameters of an AUTOSAN H921 bus lubricated with CE/SF SAE 15W/ 40 oil with the MOTOR LIFE exploitation agent Bus mileage [km] Parameters Compression pressure Start-up current [A] Exhaust smokiness [K] Zero state ~ 20,000 km Chart Select physical/chemical properties of CE/SF SAE 15W/40 pure engine oil and modified oil with the MOTOR LIFE exploitation agent within the bus mileage range of up to 20,000 km Kind of lubricating composition CE/SF SAE 15W/40 CE/SF SAE 15W/40 + MOTOR LIFE Kinematical viscosity at a Base number temperature of 100oC [mg KOH/g] [mm2/s] Bus mileage [km] Bus mileage [km] , , Iron content [ppm] Bus mileage [km] , cylinder pressure [at] 23, , , cylinder nr compression pressure state zero after km. Fig Compression pressure test results in a SW-400 engine lubricated with CE/SF SAE 15W/ 40 oil with the MOTOR LIFE exploitation agent 56

57 exhaust fume [K] 4,74 4,72 4,7 4,68 4,66 4,64 4,62 4,6 4,58 1 bus mileage zero state after km. after km. Fig Exhaust fume smokiness change in the function of bus mileage orin content [ppm] M OT OR C E/ S F..+ SA E C E/ S F LI FE 15 W /4 0 0 Fig Comparative tests results of increased iron contents in CE/SF SAE 15W/40 engine oil and modified oil with the MOTOR LIFE exploitation agent after a bus mileage of ~500, ~10,000 and ~20,000 km 57

58 Fig Comparative test results of increased iron content in CE/SF SAE 15W/40 engine oil and modified oil with the MOTOR LIFE exploitation agent after a bus mileage of ~500, ~5,000, ~10,000, ~15,000 and ~20,000 km CE/SF SAE 15W/40 2 kinematic viscosity [mm /s] 110 CE/SF SAE 15W/40 + MOTOR LIFE bus mileage [km] Fig Kinematic viscosity change of tested lubricating compositions at a temperature of 40oC conditioned with bus mileage 58

59 2 kinematic viscosity [mm /s] 15 14, , , , bus mileage[km] CE/SF SAE 15W/40 CE/SF SAE 15W/40 + MOTOR LIFE Fig Kinematic viscosity change of tested lubricating compositions at a temperature of 100oC conditioned with bus mileage start-up current [A] bus mileage zero state after km. after km. Fig Start-up current value change in the function of bus mileage with the SW-400 engine 59

60 CE/SF SAE 15W/40 base number [mg KOH/1g] 13 CE/SF SAE 15W/40 + MOTOR LIFE 12, , ,5 10 9, bus mileage [km] Fig Base number change of tested lubricating compositions in the function of bus mileage a) b) Fig Compression pressure measurement results in the engine of a NYSA vehicle lubricated with: a) CE/SF SAE 15W/40 engine oil, b) CE/SF SAE 15W/40 engine oil modified with the MOTOR LIFE exploitation agent 60

61 Fig Blotting-paper test results for the CE/SF SAE 15W/40 engine oil modified with the MOTOR LIFE exploitation agent within the bus mileage of up to 20,000 km; a) pure oil, b) pure oil modified with the MOTOR LIFE agent, c) after ~500 km, d) after ~ 5,000 km, e) after ~ 10,000 km, f) after ~15,000 km, g) oil after at a mileage of ~ 20,000 km 61

62 The obtained test results show that the modification of the SW-400 internal combustion engine lubricated with the MOTOR LIFE exploitation agent improves the lubricating conditions of friction junctions and engine exploitation parameters, which is expressed by the increase of boundary layer durability, the improvement of lubricative properties of oil during the course of exploitation, lower starting current, decreased wear of rubbing pairs (lower iron content in the oil). The presented test results and wider research concerning the subject [13] are the basis of stating that the durability and reliability of engines will increase at a considerable decrease in their noise operation and increase in oil durability - and therefore its change period LUBRICATIVE AND TRIBOLOGICAL PROPERTIES OF IBIS HPDO SAE40 ENGINE OIL CONDITIONED BY THE EXPLOITATION PERIOD OF ENGINES IN MINING CONDITIONS A variety of different processes take place in lubricating oils, operating liquids and other exploitation agents during the course of their exploitation. The processes change their contents, composition and - as a result - their properties. Since properties of oils deteriorate in time, these entire processes are called exploitation aging. Both technical devices (in which oils are used) and the external environment affect the exploitation materials. The direct impact of the technical device include: generating friction heat in movement junctions; the heat is then carried away by the exploitation liquid used in the device; oxidization catalysis of exploitation liquid components by metallic parts; interception of wear products by the oil; transmission of heat from other systems (e.g. from the combustion system); impact of liquid fuel, combustion gases, humidity (from the combustion system) and cooling liquid from the cooling system, etc. on the engine oil. Direct impact of the external environment is mainly connected with: heat exchange between the environment and the technical device (exploitation material); 62

63 infiltration of dust and humidity from the surrounding to the device interior; There might be also indirect impact of the environment on exploitation materials. It may take place through inner systems of the device, e.g. solid and liquid impurities may permeate with the intermediation of fuel, air necessary for mixture combustion, etc. Most functions of exploitation agents are complex, so is the structure and chemical composition of these materials and input functions are varied during the realization course of the machine (device) operation process. All of this cause different physical, chemical, physicochemical, mechanical and biological processes (phenomena) to take place in materials during the course of utilization. These processes lead to the degeneration of their basic properties. The typical examples of the above-mentioned phenomena are: a). physical occurrences: heating evoking evaporation, and in extreme conditions boiling of the liquid, cooling evoking loss of fluidity in extreme situations (solidification), mixing of fuel with oil (dilution); mixing of lubricating oil with the cooling factor, pollution with solid particles of different origins and of different properties; b). Physicochemical occurrences: creation of water emulsion in oil (in lubricating oils) or oil emulsion in water (in cooling and lubricating liquids), foam creation (oil + air), physical adsorption of the so-called depressants on the surface of solid impurity molecules (soot, wear products, silicon dioxide) colloidal molecules are formed and the effect of stable suspension of solid impurities in oil volume is created. c). Reactions and chemical processes: hydrocarbons oxidization (development of organic acids), non-organic acid development (e.g. SO2 hydration reaction - SO2 obtained during fuel combustion), inhibition of carbohydrates oxidization. oxidization in higher temperatures in connection with polymerization and polycondensation processes (oxygen acts as hydrogen reducing 63

64 agent from cyclic carbohydrates molecules) in the final stage molecules rich in carbon are created, Combustion of carbohydrates in the combustion chamber (in combustion engines, gas turbines); d). Mechanical processes: Shearing of viscosators molecules in toothed transmissions, in the system cylinder liner engine piston rings (shearing speed ~ 106 s-1), Destruction (shearing) of the inner structure of plastic greases; e). biological: in some materials (e.g. cooling and lubricating liquids) there are suitable conditions (e.g. water environment) for the development of bacteria, fungus and mould, i.e. for the so-called biological corrosion of the exploitation material. During exploitation of friction junctions, the contamination of the lubricating agent constitutes a very significant problem. Impurities can include solid, liquid and gas substances, that infiltrate from the outside or that form in lubricating agents during the course of operation in the lubricated device [2]. Impurities cause changes in oil properties, worsen lubrication and intensify tribological or corrosive wear of rubbing elements. The oil operating in the engine undergoes aging processes including its oxidization, thermal decomposition and contamination with substances infiltrating from the outside with the oil. At the same time, the oil operating within the combustion engine undergoes purification with the help of the filtrating system. The model of contamination and purification of oil in the combustion engine is presented in fig Fig Contamination and purification model of oil in the combustion engine [2] 64

65 The impurities infiltrating from the outside include: dust particles getting into the supply system along with fuel and air; the amount of the impurities depends on the technical condition of the supply system, on the exploitation conditions and the quality of technical engine service; water getting in with air, fuel or water contained in fresh oil. The impurities created in the engine include: technological impurities remaining in new or repaired engines after being mounted; these are particles of silicon dioxide washed out by the oil from castings, small dust or metal particles, that were not removed during production. These kinds of impurities cause damages to elements cooperating in the engine, especially in the initial stage of its exploitation; products of elements caused by the wearing process these are metal particles or metal oxide particles created as a result of tribological processes or corrosion; liquid combustion products (fuel, water, sulfuric acid and sulfurous acid). Their quantity depends on exploitation properties of the fuel, vapor pressure, sulfur content, engine operating conditions; solid combustion products are soot and carbon deposit particles as well as lead compounds, forming as a result of partial fuel combustion, oil oxidization, development of sealing waxes, coke and carbon deposits; the sizes of these impurities are mainly determined by dispersion properties of the oil; products of oil chemical change, developed as a result of oxidization, thermic decomposition and polymerization of carbohydrate oil compounds and substances being the products of disintegration and changes of additives included in the oil; cooling liquids - they can infiltrate into the oil through leaks in lubricating or cooling systems of the engine, Chemical changes of the oil are evoked by thermal impact and the impact of the air. Oxidization consists of chemical reactions between carbohydrate and oxygen. The process is very intensive during engine lubrication, when oil is present in the form of thin layers in high temperature. It takes place in the combustion chamber, in the piston and piston ring zone. The combustion chamber and the upper part of the piston are the places where partial combustion processes and thermal oil decomposition processes are in majority. 65

66 In remaining piston zones and in the oil sump, the splashing of oil and the catalytic metal effect intensifies the oxidization processes, which have a decisive meaning. Impurity concentration in the oil is the function of oil operating time in the engine. The intensity of oil pollution depends on many factors: fuel type and fuel properties; oil type; the filtration system and oil filter type; amount of added oil; technical condition and engine exploitation conditions. The oil gets polluted most intensively when the engine operates at a low rotational speed idling and when over-cooling. Worse combustion conditions and a comparatively high amount of exhaust fumes getting into the oil soot of the cold engine cause this. Moreover, the penetrating steam causes the development of low temperature deposits so-called sludge. Fig below presents the account of engine oil impurities and their classification in appropriate groups [2]. The oil undergoes oxidization, aging and mechanical destruction processes during the course of exploitation. The oxidization and aging products create sludge, carbon deposits and sealing waxes that change physicochemical properties of the oil. They often reveal strong corrosive action against metal parts, increasing the wearing of these elements. Because of this, the oil should be characterized with good oxidization resistance, it should counteract against the creation of sludge, keeping the engine clean and protecting it from corrosion. It must also fulfill the sealing function; it should cooperate with rubber and plastic seals. Different products may get into the oil during the course of exploitation, e.g. water - therefore oil should be characterized with a high degree of resistance against foaming. In practice, due to a number of reasons, the fuel in the engine does not undergo full combustion. Part of not burned products, in the form of soot, carbon monoxide, or carbohydrates is eliminated along with exhaust fumes. A part of the soot created this way along with the rest of not burned fuel and water causes the development of sludge that transforms in carbon deposits and then in sealing waxes. Sludge causes hindrance in oil circulation leading to damages of the lubricated elements. A serious problem in the operation of every engine is water, which has an impact on the engine cooperation with oil. All types of fuel contain sulfur. As a result of burning sulfur contained in 66

67 fuel sulfur oxides develop. Small amounts of water remaining in the combustion chamber interconnecting with sulfur oxides create a very corrosive environment. In extreme cases, the products may get into the oil soot. In such cases a water/oil emulsion of very fable lubricative properties may form. On the other hand, acidic products present in the oil accelerate its aging process and cause the rusting and corrosion of all lubricated parts of the engine. To limit these unfavorable effects, special anti-rust and anti-corrosive additives are added into the oil. ENGINE OIL IMPURITIES EXTERNAL Water INTERNAL Combustion products Products of oil chemical change Fuels Oxidixation products Soot Thermal decomposition products Acids Products of wearing additives Products of tribological wearing Cooling liquid Technological impurities Water Sulfur and lead compounds Fig Division of impurities and engine oil impurities sources [2] Another method of engine corrosive wear limitation is the neutralization of acidic combustion products. In order to achieve this, enriching additives are added to the oil to give the oil neutralization ability. The neutralization ability measurement of the oil is the total base number (TBN). The general rule is: the higher the sulfur content in the fuel, the higher the base number (TBN) should be. During the course of engine exploitation sludge develops within the engine. In the initial stage particles are so small that the oil filter is unable to intercept them. Circulating with the oil they merely increase the viscosity of the oil. In later stages, however, they begin to join and settle on engine walls. 67

68 Then the carbon deposit conversion process begins, followed by the conversion into sealing waxes. To prevent this from happening washing and dispersing agents are added to oils, which cause: constant washing out of sludge, carbon deposits and sealing waxes from the surface of walls, maintaining the engine interior clean; maintaining sludge and washed out carbon deposits in a dispersed state (dissolved in oil) making their separation from the oil filter possible. The measure of presence and quantity of washing and dispersing agents is the TBN base number. The higher the oil base number, the better are its washing abilities, and thus the engine will be kept clean longer and also its efficiency as well as life span will be longer. Oil deterioration during the course of engine operation consists of oxidization and polymerization of carbohydrates, the forming of acids and resins, the increase in content of mechanical impurities, the decrease in concentration of additives and changes in other properties. During the exploitation period, the oil quality is subject to change (deteriorate) in time. Oil deterioration is connected with the change of its physicochemical properties due to the impact of high temperature and oxygen in the air and the catalytic impact of metals as well as mechanical shearing forces. As a result of oil deterioration the following actions take place: coloration change; acid value increase; base number value decrease; forming of deposits and sealing waxes; increase in content of solid particles (mechanical impurities); viscosity change, etc. The factors causing the loss of physicochemical properties of engine oil during the course of exploitation are: high temperatures, high pressure, high engine load, gas scavenges from the combustion chamber, low external temperatures (exploitation in winter conditions). The enriching additives being a part of oils play a very significant role in engine exploitation. During the engine exploitation process, the enriching additives can lose their effectiveness: 68

69 naturally, fulfilling its functions (if the additive has chemical functions, it is irreversible, physical occurrences - e.g. adsorption are reversible); in an emergency through: - thermal decomposition; - hydrolysis (and transition to deposit); - mechanical shearing (concerns mainly viscosity additives chain polymers). It is obvious that in case of anti-corrosion additive insufficiency, the oil starts to have a negative impact on metallic parts. If the viscosator sustains damage viscosity will decrease, etc. A continuous problem in Polish copper mining establishments is the accelerated abrasive and corrosive wear of tribological elements due to impurities and the change in oil lubricative properties. The KGHM Company has a number of vehicles and heavy mining machines used in particular heavy duty conditions mining conditions. Exploitation in mines is connected with higher temperature, dustiness, smokiness, noise, difficult traction conditions, etc. As a result of higher engine operating temperatures, the engine oil oxidizes more easily; they lose required properties and produce aging products undesirable for the engine. In such conditions, vehicles and machines are generally less resistant and are expended very quickly. Are there any possibilities lubrication technologies that could prevent this from occurring or that could limit this drawback? The answer to this important question are the test results presented below, concerning the impact of mining impurities on lubricating and application properties of IBIS HPDO SAE 40 engine oil used among others in SW 680 engines operated in ZG Rudna. One season mineral IBIS SAE 40 engine oil belongs to the HPDO (High Performance Diesel Oil) [4] category. It is an oil of the newest generation for engines of high-pressure machines and devices operating in a specific exploitation condition such as e.g.: mining (mining machines), agriculture, rail. It can operate in all engines with and without turbo chargers. It is not recommended for engines with spark ignition. Carefully chosen set of components both of oil based and enriching additives give the oil properties that allow it to be included in the category of best oils defined as High Performance Diesel Oil. 69

70 The IBIS oil: possesses splendid lubricative properties in all engine operating conditions; maintains the oil filter continuity in high temperatures; ideally protects all engine elements from wear; keeps the engine ideally clean; protects the engine from corrosion; decreases the emission of harmful substances into the atmosphere; low evaporative power decreases oil loss through evaporation. It can be applied to all engines, to which the producer recommends the application of CE class oils, as well as to all high-pressure engines with a construction characteristic that of the 90s. The oil is mainly applied in the engines of contemporary machines and devices operating in extreme exploitation conditions. The oil is entirely miscible with other oils of the same quality and viscosity class. In order to run tests, a LK-2 type loading machine was used. It was used in mining conditions (SW 680 engine, MTh , production year: 1997). The pure IBIS HPDO SAE 40 oil and the same oil with a 5% addition of the MOTOR LIFE exploitation agent were used as lubricating agents. The samples of lubricating compositions for the tests were taken in the following order: 1. pure oil sample, 2. used oil sample after 9 Mth, 3. used oil sample after 200 Mth, 4. used oil sample after 400 Mth, 5. oil sample with the MOTOR LIFE exploitation agent, 6. oil sample with the MOTOR LIFE exploitation agent after 9 Mth, 7. oil sample with the MOTOR LIFE exploitation agent after 200 Mth, 8. oil sample with the MOTOR LIFE exploitation agent after 400Mth. The test results concerning lubricative properties of lubricating compositions after different exploitation periods are presented in chart 2.7. Resulting from chart 2.7 and fig is that adding 5% of the exploitation agent into the oil improves lubricative properties both in increasing the antiseizure properties of the lubricating agent the increase of wear under load factor Ih from to dan, boundary wear load Goz from to dan, as well as the durability increase of the lubricating layer increase of load causing seizure Pt from to dan. 70

71 The variability course of the friction force for friction junctions submitted to growing load fig illustrates the lubricative property improvement of oil modified with the MOTOR LIFE agent. Resulting from fig is that for the entire range of load, the course of friction force for the modified oil remains at a lower level. The boundary layer rupture occurred in a later stage as well. In case of pure oil, the rupture occurred after 5.6 sec and in case of the modified oil after 7.2 sec. This means that the friction junction lubricated with oil enriched with the addition of MOTOR LIFE is able to sustain greater dynamic and temperature loads. Chart 2.7. Lubricative properties of IBIS HPDO SAE 40 engine oil and oil modified with the MOTOR LIFE exploitation agent. LUBRICATIVE PROPERTIES [dan] Lubricating composition Commercial oil Commercial oil + 5% MOTOR-LIFE Pz Ih Pn Pt Goz Pz Ih Pn Pt Goz Engine oil IBIS HPDO SAE 40 after 200MTh Engine oil IBIS HPDO SAE 40 after 400MTh Pure IBIS HPDO SAE 40 engine oil Engine oil IBIS HPDO SAE 40 after 9MTh The analysis of changes in lubricative properties in the function of engine oil exploitation period length (chart 2.7 and fig and ) shows that during the entire time span of engine oil exploitation, the modified oil with the MOTOR LIFE agent shows better lubricative properties. In case of pure oil, after an operating time equal to ~400 MTh, the indicator of load causing welding Pz decreased to 160 dan, and in case of modified oil was maintained at the level of 200 dan. The improvement of lubricative properties of IBIS HPDO SAE40 oil modified with 5% of the MOTOR LIFE exploitation agent has been confirmed through tests of friction junction tribological properties fig The tests have shown that during the entire range of oil exploitation, the 71

72 Friction force [dan] lubricating composition with the addition of the agent has an impact on the decrease of friction resistance (lower friction force fig ) as well as on the decrease of wear fig The favorable impact of the MOTOR LIFE agent has been confirmed in exploitation conditions. The pressure measurements in engine cylinders after 400 MTh (fig. 2.61) have shown that the MOTOR LIFE agent improves lubricating conditions the pressure in cylinders is higher. In cylinders 1 and 5 the pressure increased by 4 MPa. The pressure charts for particular cylinders are shown in fig The charts show that the pressures in cylinders have been equalized. It is very important because of crankshaft bearings loading uniformity. It is a rule that the highest increase of pressure occurred in cylinders having the lowest initial pressure. The picture of impurity change taking place during the course of exploitation of the tested compositions based on the blotting-paper test is shown in fig The characteristic feature of both the pure oil and the modified oil with the MOTOR LIFE agent is the considerable coloring occurring directly after the engine operation equaling ~ 9 MTh it is the effect of mixing the remaining oil with fresh oil after changing oil. There is a difference between the coloring of IBIS HPDO SAE40 oil and modified oil with MOTOR LIFE after 400 MTh as well. The oil with the addition of the agent is much lighter, which signified lower wear of rubbing pairs. Recapitulating, the test results show favorable impact of the MOTOR LIFE exploitation agent on combustion engine operation, because they improve lubricating conditions and boundary layer durability, and thus they improve the exploitation parameters of the engine as well as its durability and reliability Pz Pn Ih Pt Goz IBIS HPDO IBIS HPDO SAE 40 po SAE 9MTh 40+Motor Life po 9MTh Fig Lubricative properties of IBIS HPDO SAE40 engine oil and oil modified with the MOTOR LIFE exploitation agent 72

73 friction force [dan] Pz Ih Pn Pt Goz IBIS HPDOIBIS HPDO SAE 40 SAE 40+Motor Life friction force [dan] Fig Lubricative properties of IBIS HPDO SAE 40 engine oil and oil modified with the MOTOR LIFE exploitation agent after the LK-2 mining machine engine operation equaling ~ 9MTh Pz 250 Ih Pn Pt 100 Goz 50 0 IBIS HPDO IBIS HPDO SAE 40 po SAE 200MTh 40+Motor Life po 200MTh Fig Lubricative properties of IBIS HPDO SAE 40 engine oil and oil modified with the MOTOR LIFE exploitation agent after the LK-2 mining machine engine operation equaling ~ 200 MTh 73

74 Friction force [dan] 200 Pz 150 Ih 100 Pn Pt 50 Goz 0 IBIS HPDO IBIS HPDO SAE 40 po SAE 400MTh 40+Motor Life po 400MTh 5 4,5 4 3,5 3 2,5 2 1,5 1 0,5 0 Liczba zasadowa [mg KOH/1g] Friction force [dan] Fig Lubricative properties of IBIS HPDO SAE 40 engine oil and oil modified with the MOTOR LIFE exploitation agent after the LK-2 mining machine engine operation equaling ~ 400 MTh 13 CE/SF SAE 15W/40 IBIS 12,5 CE/SF SAE 15W/40 + MOTOR LIFE IBIS+Motor Life 12 11, ,5 10 9,5 0 0,8 2, , Przebieg [km] 7,2 autobusu 8,8 10, ,6 15,1 16,8 time [s] Fig The variability course of friction force for changing (growing) load on the friction junction for IBIS HPDO SAE40 engine oil and oil modified with the MOTOR LIFE exploitation agent 74

75 Friction force [dan] 5,5 5 4,5 4 3,5 3 2,5 2 1,5 1 0,5 0 IBIS 9 MTh IBIS+Motor Life 9MTh 0,8 2,4 4 5,6 7,2 8,8 10, ,6 15,1 16,8 time [s] Fig The variability course of frictio force for changing (growing) load on the friction junction for IBIS HPDO SAE40 engine oil and oil modified with the MOTOR LIFE exploitation agent after the LK-2 mining machine engine operation equaling ~ 9 MTh Friction force [dan] 3,5 IBIS 200 MTh 3 IBIS+Motor Life 200MTh 2,5 2 1,5 1 0,5 0 0,8 2,4 4 5,6 7,2 8,8 10, ,6 15,1 16,8 time [s] Fig The variability course of friction force for changing (growing) load on the friction junction for IBIS HPDO SAE40 engine oil and oil modified with the MOTOR LIFE exploitation agent after the LK-2 mining machine engine operation equaling ~ 200 MTh 75

76 Friction force [dan] 4,5 4 3,5 3 2,5 2 1,5 1 0,5 0 IBIS 400 MTh IBIS+Motor Life 400MTh 0,8 2,4 4 5,6 7,2 8,8 10, ,6 15,1 16,8 time [s] Fig The variability course of friction force for changing (growing) load on the friction junction for IBIS HPDO SAE40 engine oil and oil modified with the MOTOR LIFE exploitation agent after the LK-2 mining machine engine operation equaling ~ 400 MTh 25,0 friction force [dan] 20,0 15,0 10,0 IBIS 5,0 IBIS+MOTOR LIFE 0, time [s] Fig The variability course of friction force for the friction junction lubricated with IBIS HPDO SAE40 engine oil and oil modified with the MOTOR LIFE exploitation agent 76

77 25,0 friction force [dan] 20,0 15,0 10,0 IBIS - 9MTh 5,0 IBIS+MOTOR LIFE - 9MTh 0, tim e [s ] Fig The variability course of friction force for the friction junction lubricated with IBIS HPDO SAE40 engine oil and oil modified with the MOTOR LIFE exploitation agent after 9 MTh 25,0 friction force [dan] 20,0 15,0 10,0 IBIS - 200MTh IBIS+MOTOR LIFE -200MTh 5,0 0, tim e [s ] Fig The variability course of friction force for the friction junction lubricated with IBIS HPDO SAE40 engine oil and oil modified with the MOTOR LIFE exploitation agent after 200 MTh 77

78 25,0 friction force [dan] 20,0 15,0 10,0 IBIS - 400MTh IBIS+MOTOR LIFE - 400MTh 5,0 0, tim e [s ] Fig The variability course of friction force for the friction junction lubricated with IBIS HPDO SAE40 engine oil and oil modified with the MOTOR LIFE exploitation agent after 400 MTh 0,05 weight loss [g] 0,04 without additive with additive 0,03 0,02 0,01 0, oil operating time[mth] Fig Change of weight loss of samples lubricated with IBIS HPDO SAE40 oil and samples lubricated with oil modified with the MOTOR LIFE agent conditioned with the time of engine operation 78

79 Friction force [dan] Siła tarcia [dan] Nr. cylindra IBIS IBIS+MOTOR LIFE po 400MTH Fig Results of compression pressure measurements in SW-680 engine cylinders lubricated with IBIS HPDO SAE40 and oil modified with the MOTOR LIFE exploitation agent a) b) Fig Results of compression pressure measurements in SW-680 engine cylinders after 400 MTh lubricated with: a) pure IBIS HPDO SAE40 oil, b) IBIS HPDO SAE40 oil with the addition of the MOTOR LIFE exploitation agent 79

80 a) b) c) d) e) f) g) h) Fig Results of the IBIS HPDO SAE engine oil blotting-paper test $) in the range of mining loading machine exploitation of LK-2 type up to 400 MTh; a) pure IBIS oil, b) pure IBIS oil modified with the MOTOR LIFE agent, c) IBIS after ~ 9 MTh, d) IBIS+MOTOR LIFE after ~ 9 MTh, e) IBIS after ~ 200 MTh, f) IBIS+ MOTOR LIFE after ~200 MTh, g) IBIS after ~ 400 MTh, h) IBIS+MOTOR LIFE after ~ 400 MTh. 80

81 2.5. EVALUATIING NOISE EMISSION AND POWER DEMAND FOR MACHINERY AND VEHICLES Noise is one of the most troublesome elements of the human environment. It is harmful, unpleasant and undesirable. Acoustic vibrations movement of elastic environment molecules in relation to the state of equilibrium generate noise. Air can act as an environment, in which vibrations are often called air acoustic vibrations, as oppose to vibrations occurring within solid matters that are called material acoustic vibrations. Vibrations capable of creating aural impression are called sounds. Acoustic vibrations audible for humans are vibrations of frequencies between border values of 16 and 16,000 Hz. Even a short stay in high levels of noise causes acoustic fatigue (limited audibility) that may prove to be momentary or permanent. Whether or not it is harmful for audition depends first of all on its level. It is assumed that the sounds of volume lower than 2535 db are indifferent to humans, they are bearable between db, troublesome from db and those over 85 phons are harmful. One of the main sources of noise can be that of machinery and devices. Their elements and sub-assemblies cause audibility often exceeding 80 db. The decrease of loudness even by a few decibels is a considerable success, related with the improvement of operating conditions in production halls and even their surroundings. The main sources of noise in machines and devices are: bearings (slide and rolling ones); toothed gears; engines. Fundamental significance for vibration damping is attributed to the sort of material of which the elements and the body of the machine are built. A. Bearings. As [27] presents, the main noise source of slide bearings is friction between the operating surface of the pivot and the bearing liner. The noise reduction issue of these kinds of bearings is first of all verified through decreasing the friction factor to the lowest possible value. In case of dry friction, the value of this factor varies from 0.2 to 0.4 and in case of mixed friction between and lower. In both cases the sliding surfaces of the bearing come to direct contact with each other, and the operation of the bearing proceeds at an intermittent motion. Vibrations in connection with such motion may increase and take the form of noise, especially in case of 81

82 conformity of vibration frequencies of the bearing and elements directly bound to it. In case of liquid friction, the operating surfaces of the pivot and the bearing liner do not come to direct contact with each other, because they are separated by a layer lubricating agent - the bearing operation proceeds in a continuous motion and the noise level is lower. In this case the vibrating layer of grease can become the source of vibrations. During the operation course of the bearings, the noise can be caused by the increased friction factor, e.g. due to insufficient inflow of the lubricating agent, overload of the bearing, changes in the direction of the element rotating in the bearing, etc. In all these cases, the layer of the lubricating agent becomes thinner, and the summits of pivot roughness and bearing liner surfaces touch each other and begin to rub away. Not only does the overload increase noise, but also it accelerates the wearing process of operating surfaces and the bearing wear. The problem of pivot and bearing liner-machining accuracy gains special significance, ensuring good lubrication and using bearings built from materials capable of inner vibration dampening (cast iron, plastics). The rotational speed of the shaft mounted in the bearing has an impact on the noise level of the slide bearing. The noise increases along with the increase in speed. Rolling bearings are noisier than slide bearings. The replacement of a rolling bearing with a slide bearing may cause noise reduction by 15 to 25 db. The noise sources of rolling bearings [27] are first of all deviations of the proper shape of the track. The deviations may be the cause of unilateral periodical overloads of one part of the bearing and local friction increase. The noise level of rolling bearings depends on the diameter and rotational speed of the bearing. For a given type of bearings, the noise level increases altogether with the increase of its diameter. B. Toothed gears. Another typical machine assembly, constituting the source of intensive noise is the toothed gear. As soon as a pair of toothed wheels begin to turn, consecutive pairs of teeth mesh. The transmission of torque to every other pair of teeth is connected with the occurrence of a percussive impulse. Such an impulse is composed of: - local micro strokes of teeth pairs meshing at a given moment - slide and rubbing along operating parts of both teeth sides as a result of friction force direction change 82

83 - local micro-stroke occurring at the moment when the pair active so far transmits all its load to the next pair. Because the three occurrences repeat on a periodical basis, they are not distinguished and the feeling of noise tone is determined by the frequency of specific basic impulse repetition. It is worth mentioning that a single basic impulse evokes proper damped vibrations. The increase of rotational speed of the transmission shortens the intervals between particular impulses not only increasing the frequency of these impulses but the transmission noise level as well. Depending on the exploitation conditions, the toothed gears can operate under variable loads - e.g. car gears, or loads of constant value - e.g. industrial gears. The level of noise depends first of all on the power transmitted by specific transmission and other factors like the exactitude of the scale, exactitude of the treatment and lubrication, the meshing type, resonance impact of bearings, shaft, casing etc. The impact of treatment inaccuracy can be alleviated to a certain extent through lubrication, although physical properties of grease like viscosity and temperature do not have much significance in this case. What is important is the covering degree of teeth operating surfaces with the lubrication agent. When teeth of wheels were only covered with a thin layer of grease the initially low noise heard at a comparatively quiet gear suddenly increased by 14 db. During this time wheels operated in dry conditions. The possibility of noise reduction with help of lubrication is estimated at approximately 4-6 db [27]. C. Engines. There are a number of noise sources within internal piston combustion engines. In general, the noise of piston combustion engines may have mechanical origins and can also be connected with the flow of combusted gases in the engine exhaust system. Generally, the main source is aerodynamic reasons and noise control is usually achieved through the use of mufflers of an appropriate construction, mostly resonant ones. Electric engines are used very widely as a drive for many machines. Therefore, in case they have to cooperate with devices or machines that are demanded to operate in an especially quiet manner, the noise level of such engines should be as possibly low as well. In general, the noise of electric engines may have its origin in its mechanical, aerodynamic and magnetic character. The reasons for mechanical noise are bearing vibrations, insufficiently balanced rotating elements of the 83

84 engine and carbon brushes hitting against the commutator or the brush mountings. The operating condition variability of toothed gears in conditions of mixed friction and boundary friction causes their accelerated wear (excessive backlash, noisy operation) regardless what the construction solution and materials used, and regardless of the production technology applied. In extreme situations it may even cause damage - surface seizure, breaking of teeth, etc. The temperature increase of the transmission - e.g. as a result of applying unsuitable oil or imposing an excessive load, speeds up the wearing process of materials that they are made of. Having this in mind, the issue of proper lubrication of toothed gears friction junctions gains special significance. The problem is very complex because in many cases the actual loads of friction junctions, temperature, etc. are unknown. The variability of operating conditions determines the kind of friction, which most often turns out to be mixed friction (start-up or stopping with a considerable share of dry friction), boundary, and rarely liquid friction in normal operating conditions. The transition of one instance to the other is caused by: surface geometry of touching teeth; variability of operating conditions (start-up, speed change and others); roughness of surfaces after grinding-in; variable oil viscosity depending on its temperature. The complexity of processes taking place in the friction junction of toothed gears, therefore places very high demands for lubricating agents especially within the range of boundary layer durability, the measuring instruments of which are: the ability of transmitting loads and durability against the impact of high temperatures. Good lubricating indicators should characterize the oils. Indicators include: the welding load Pz, wear under load factor Ih, highest load not causing seizure Pn and the load causing seizure Pt. Although the best transmission oils are used (class GL-4, GL-5), there are still cases of insufficient lubrication of rubbing transmissions. Taking the above into consideration, the program of tests carried out within the range of operating condition modification with the use of exploitation agents also included the case with toothed gears. Tests were conducted in order to improve oil lubricative property indicators, and therefore to decrease the operating noise and improve operational durability and reliability. 84

85 noise [db] The aim of the conducted research was to determine the impact of exploitation agents on lubricative properties of transmission oils as well as on the noise and current intake. The measuring of noise and current intake were carried out in industrial conditions. The measuring of noise was carried out according to PN-90/S with the use of a Sonopan Meter P-01 sound level meter and the power intake was measured by Aron's system - a special measuring set. The fig.2.46 and 2.47 show exemplary diagrams illustrating the variability of 1H 983 lathe operating noise, which toothed gear was lubricated with pure M26 oil and in another case - with the same oil, but after modification with the MOTOR LIFE exploitation agent. As it results from fig.2.46, there has been a decrease of operating noise (in some case even down to 4dB) as a result of the modification within the entire range of tested rotational speeds of the spindle (for all different speeds, different pairs of toothed gears creating kinematic chain of movement transmission are involved). Fig illustrates machine tool operating noise distribution. And in this case the effects of modification are clearly visible. It is also worth mentioning that the operating noise has been decreased down to 4 db in the work place. The executed tests of current intake have shown - fig. 2.84, that the MOTOR LIFE exploitation agent also has impact on the decreased current intake by approximately 2%, which has a significant economical meaning. M26 oil The impact area of the MOTOR LIFE agent M26 oil + MOTOR LIFE speed [rpm] Fig The impact area of the MOTOR LIFE exploitation agent on 1H 983 pipe lathe operation noise 85

86 Test results on noise intensity carried out on a ZFB-50 milling machine for toothed wheels fig and 2.50 as well as results concerning the current intake (fig. 2.51), which fixed headstock transmission and the hobbing cutter of the machine were both lubricated with M 26 oil machine fed from the same source, are the confirmation of favorable impact of MOTOR LIFE. The tests show that as a result of modifying lubricating conditions the current intake decreased by approximately 4%. This is the effect of lubrication conditions improvement - the decrease of movement resistance. During the tests it was found that the durability of the machine cutting tool was increased by approximately ~ 30%. M26 oil position of worker M26 oil + MOTOR LIFE Fig The impact of the MOTOR LIFE exploitation agent on the operation noise around the 1H983 lathe at a spindle rotational speed of n = 280 rpm. 86

87 power [W] M26 oil The impact area of the MOTOR LIFE agent M26 oil + MOTOR LIFE speed [rpm] Fig The impact area of the MOTOR LIFE exploitation agent on the 1H 983-lathe power intake noise [db] within the maximum noise level within the minimum noise level speed [rpm] Fig The impact of the MOTOR LIFE exploitation agent on the ZFB-50 hobbing machine operation noise 87

88 Background level 53dB Maximal noise level allowed: 82 db measuring points around the machine Fig The impact of the MOTOR LIFE exploitation agent on the ZFB hobbing machine operation noise at a spindle rotation speed of n=160 rpm. power [W] M26 oil The impact area of the MOTOR LIFE agent M26 oil + MOTOR LIFE speed [rpm] Fig The impact area of the MOTOR LIFE exploitation agent on the ZFB-50 hobbing machine power intake 88

89 2.6. SHAPING OF TECHNOLOGICAL QUALITY AND SURFACE LAYER EXPLOITATION MACHINE CUTTING PROCESS The type of lubricating/cooling liquid is one of the most important factors determining the quality of the technological surface layer and the resistance during the machine cutting process of friction junctions (e.g.: turning). The type of liquid determines the kind of friction occurring during the machine cutting process - it increases the share of mixed friction and boundary friction. Temperature in the friction zone decreases (the cooling role of the liquid). This has a significant meaning for the course and the intensification of the phenomena taking place within the machine cutting zone as well as within surface layers of the treated material and tool. Improving operation conditions of the friction junction favorably affects the geometrical condition of the surface - smaller roughness of the surface and has an impact on decreasing machine cutting resistance and therefore decreasing the power intake. Improving lubricating conditions signifies a greater durability of the tool and its slower deterioration (a greater stability of the tool geometry) and therefore a greater stability, roughness homogeneity and the homogeneity of geometrical structure of the surface. The confirmation of the above statements is the tests results illustrated in fig The highest roughness of the surface Ra = 2,4 µm was achieved when turning iron dry - fig The use of a lubricating agent causes a considerable decrease of surface roughness. In case Emulgol was applied, the roughness was decreased to the level of Ra=1,89 µm, and in case of machine oil M10 - to the value of Ra = 1,6 µm. In case the MOTOR LIFE agent was used (5%), the roughness for Emulgol decreased to the level of Ra = 1,67 µm, and in case of M10 machine oil to the lowest value Ra = 1,30 µm. 89

90 dry emulgol emulgol+motor L. oil M10 4 3,5 3 oil M10+MOTOR L. 2 1,5 Ra [um] 2,5 1 0,5 dry 0 emulgol emulgol+motor L oil M oil M10+MOTOR L speed [rpm] 1400 Ra [um] Fig.2.52.The impact of machine cutting speed and lubrication type on surface roughness during the turning process of steel45. Processing conditions: f = 0,21 mm/tr., a = 0,5mm, cutting tool NNZc 25x25 S10 16 dry emulgol emulgol+motor L. 14 oil M10 12 oil M10+MOTOR L dry 4 emulgol 2 emulgol+motor L. 0 oil M10 0,39 0,27 impact rate 0,2 oil M10+MOTOR L. 0,13 0,08 Fig The impact rate of feed and lubrication type on the surface roughness during the turning process of steel 45. Processing conditions: n = 900 rpm., a = 0,5mm, cutting tool NNZc 25x25 S10 90

91 2,5 Ra[um] 2 1,5 1 0,5 oil M10+MOTO R LIFE oil M10 em ulgol 1 em ulgol +MOTOR LIFE dry 0 Fig The impact of the lubricating agent type on the surface roughness during the steel turning process. Processing conditions:: f = 0,13 mm/tr. n = 1120 rpm., a = 0,5 mm, cutting knife NNZc 25x25 S BURNISHING PROCESS Tests [13, 19, 29] show, that one of the most important factors determining the functional properties, including tribological properties of machine elements, is the state of their technological surface layer (TSL). TSL is being constituted during the machine cutting process of elements, especially in final operations, i.e. surface machine cutting. One of the methods of (improving) surface machine cutting is burnishing. Burnishing causes the formation of very favorable geometrical surface properties - low surface roughness, characteristic geometrical surface structure characterized by very high gradients of bearing surface G20 and G50 and physical and mechanical surface layer gradients, i.e. structure refinement, its consolidation and creation of squeezing tensions [13, 19, 29]. The TSL state is dependent on many factors after the burnishing process, and in particular [19]: type of processed material; type of machine processing (static, dynamic, oscillatory); type of tool and its construction parameters; burnishing technological parameters; other. 91

92 Although the impact of the above-mentioned factors on the TSL condition has been thoroughly examined, there has not been much research made on the impact of the type of lubricating agent. It is commonly accounted for that e.g. cast iron is burnished without the use of a lubricating agent (dry) and that steel is burnished with the use of kerosene and oil. In study [21] the attention is turned to the fact that friction/wear tests of burnished parts should be conducted. During such tests additives increasing lubricating abilities of oils (oxygen, sulfuric, phosphate compounds, and other) would be introduced into surface layers. TSL shaped in the presence of these additives - Fig should be characterized with favorable tribological properties - the additives introduced into the surface layer in the burnishing phase should activate during the exploitation stage improving lubricating conditions on rubbing surfaces. The following part of this study pays attention to this issue. The aim of the test was to show whether or not and how the lubricating agent (oil, exploitation agent) has impact on the tribological properties (friction factor and wear) of the roller burnished cast iron. The tests were carried out on spheroidal ferrittic-pearlite cast iron of a hardness factor of ~2300 MPa as well as a chemical composition of: C = 3.20 %, Mn = 0.33%, Si = 1.945, P = 0.016% and S = 0.005%. The burnishing was carried out on a TUD-50 roller with a special tool - a roller of the diameter of ø50 mm and the rounding radius of r = 20 mm. The following oils or exploitation agents were used as lubricating agents: SN 150 base oil free from oil enriching additives; TITAN CFE 1040 MC engine oil, containing the molybdenum dioxide among enriching additives; MOTOR-LIFE- exploitation agent evoking chemical actions. Tribological tests were carried out with the use of a T-05 tribometer produced by ITE Radom - matching the burnished sample with the block (steel, flat counter sample hardness of 60 HRC) lubricated each time with SN 150 base oil. Tests were carried out in two stages. Stage I grinding in at four turning speeds 60, 120, 180, 240 rpm and pressure forces of 30 and 60 N over the time of 30 sec; Stage II the principle tests (without the disassembling of the rubbing connection) at the speed of 180 rpm and the pressure force of 60 N over 1 hour. Fig illustrates an exemplary profilogram of a surface after the treatment preceding burnishing after rolling, whereas chart 2.6 illustrates the changes in roughness during the process of technological surface treatment 92

93 and after the utilization process (wear out). Shaping of different lubricating composition surfaces took place during the technological stage. F roller motion direction roller shape R a) A1 B1 A2 B2A3 C1 B3 C2 roughness shape after pre-processing s ly e c rfa u y b ife d o m itg lo p x e n a z R t b) R C3 roller shape Fig Surface roughness deformation during the process of roller burnishing: a) diagram of inner forces arrangement and the roughness deformation course, b) surface layer modification diagram with exploitation agents Chart 2.6. Values of roughness changes of surfaces during the process of technological surface treatment and after the wearing process of ferritic- pearlitic spheroidal cast iron Kind of treatment or process rolling burnishing wear Surface roughness Ra [µm] Lubricating composition type Base oil SN Engine oil TITAN CFE 1040 MC MOTOR LIFE exploitation agent

94 Chart 2.6 and fig show that in case of all tested lubricating compositions, the roughness of surfaces is similar and is equal to R a = µm. Roughness is the highest, however, in case of applying the SN 150 based oil lubricating agent - Ra = 0,57 0,67 µm. An exemplary view of the geometrical structure after rolling and burnishing with the MOTOR LIFE exploitation agent is presented in fig After the burnishing process (fig.2.58b), a distinct deformation of apex roughness is visible the on surface (lighter areas). During the friction process on rubbing surfaces different geometrical structure are shaped and conditioned by operating conditions. Profilograms surfaces after the friction process for different lubricating conditions during the burnishing process are presented in fig As it results from the drawing, in this case, within the range of roughness the differences are not significant, characteristic for the friction between steel and cast iron. The results of tribological property tests of friction junctions depending on the pressure and variable speed values are presented in fig As it results from fig. 2.60, the friction force is more favorable for the surface burnished in the presence of the MOTOR LIFE agent. Within the range of friction junction temperature change, there have been no significant changes (fig. 2.61), and within the range of the lubricating agent temperature, the lowest values were achieved for the sample burnished in presence of the MOTOR LIFE agent. Slightly higher values were achieved for the sample burnished in the presence of TITAN CFE 1040 MC engine oil and the highest values for the sample burnished in case of SN 150 base oil (fig. 2.62). Fig illustrate the results of tribological properties of the same rubbing pairs that were tested before (without disassembling friction junctions). The presented results are the values for constant a given load of P = 30 N and a rotational speed of n = 360 rpm over the time of t = 1 hour. The test results show that in this case, the friction force (fig. 2.63) is most favorable for the surface burnished in the presence of the MOTOR LIFE agent. Temperature changes of the friction junction (fig. 2.64) and lubricating agent (fig. 2.66) confirm the favorable impact of the MOTOR LIFE agent. The results of wear testing (fig. 2.66) have shown that the lowest wear occurred in case of the surface burnished in the presence of the MOTOR LIFE agent, the second lowest in case of TITAN CFE 1040 MC and the highest wear occurred in case of applying SN 150 base oil. Examinations of wear 94

95 areas presented in fig and 2.68 were confirmed by the results of the above-mentioned tests. The analysis of the research results shows that the surface burnished in the presence of MOTOR LIFE has the most favorable tribological properties. During the burnishing process, the lubricating agent modifies the surface layer thanks to lubricating additives as a result of physical and chemical sorption. It should be assumed that the MOTOR LIFE agent also penetrates the emission of graphite during the burnishing process. The emissions of graphite become natural containers. They become activated during the friction process improving tribological properties of the friction junction. The conducted research has shown the possibility of constituting tribological surface layer properties through the application of chemical compounds or exploitation agents during the process of cast iron burnishing and probably the burnishing of steel as well. The tribological properties of the friction junction improve through the modification of the surface layer lower friction factor and lower wear. Though the conducted research does not solve the research problem. Fig Exemplary profilogram surface after the process of spheroid ferriticpearlite cast iron rolling (treatment preceding burnishing) Treatment conditions: f = 0,21 mm/tr., a = 0,5 mm, n = 910 rpm., tool- knife NNZa 25x25 S10 a) b) 95

96 c) Fig Profilogram surfaces after the spheroid ferritic-pearlite cast iron burnishing process in the presence of different lubricating compositions: a) SN 150base oil, b) TITAN CFE 1040 MC engine oil, c) MOTOR LIFE exploitation agent. Treatment conditions: fn=0,21 mm/tr., P = N, n = 450 rpm. a) b) Fig Microphotograph of spheroidal ferritic-pearlite cast iron: a) after the burnishing process, b) after the burnishing process in presence of the MOTOR LIFE exploitation agent. Magnification: 100x a) 96 b)

97 c) Fig Profilogram surfaces after wear tests of burnished cast iron in the presence of: a) SN 150 base oil, b) TITAN CFE 1040 MC engine oil, c) MOTOR LIFE exploitation agent 12,000 friction force[dan] 10,000 8,000 6,000 SN 150 4,000 TITAN MOTOR LIFE 2,000 0, time [s] Fig The course of friction force variability in relation to friction force and friction junction load for cast iron after burnishing in presence of: SN 150 base oil, TITAN CFE 1040 MC engine oil and MOTOR LIFE exploitation agent 97

98 tem perature [oc] SN ,000 T IT AN 2 8,000 M OT OR LIFE 2 3, , t im e [s] Fig The course of friction junction temperature variability in relation to speed and load of friction junction for cast iron after burnishing in the presence of: SN 150 base oil, TITAN CFE 1040 MC engine oil and MOTOR LIFE exploitation agent temperature [oc] 29,000 27,000 25,000 SN 150 TITAN MOTOR LIFE 23,000 21,000 19, time [s] Fig The course of lubricating agent temperature variability in relation to speed and friction junction load for cast iron after burnishing in the presence of: SN 150 base oil, TITAN CFE 1040 MC engine oil and MOTOR LIFE exploitation agent 98

99 10,5 temperature[oc] 10,0 9,5 9,0 8,5 8,0 SN150 7,5 TITAN 7,0 MOTOR LIFE 6,5 6, time [s] Fig The variability course of friction forces present in the friction junction steel/spheroidal ferritic-pearlite cast iron after burnishing. The type of burnishing during the burnishing process: SN 150 base oil, TITAN CFE 1040 MC engine oil, MOTOR LIFE exploitation agent 48,0 temparature [oc] 43,0 SN 150 TITAN MOTOR LIFE 38,0 33,0 28,0 23,0 18, time [s] Fig The course of friction junction temperature variability in relation to given speed and friction junction load steel/spheroidal ferritic-pearlite cast iron after burnishing. The type of lubrication during the burnishing process: SN 150 base oil,, TITAN CFE 1040 MC engine oil, MOTOR LIFE exploitation agent 99

100 33,0 28, , ,0 337 SN 150 TITAN MOTOR LIFE 295 temperature [oc] 38,0 time [s] Fig The variability course of oil temperature in the friction junction steel/spheroidal ferritic-pearlite cast iron after burnishing. The type of lubrication during the burnishing process: SN 150 base oil, TITAN CFE 1040 MC engine oil, MOTOR LIFE exploitation agent 0,2 wear [mm 3] oil SN 150 0,15 0,1 oil Titan Motor Life 0,05 0 Fig Steel wear test results in case of cooperation with cast iron when applying different lubricating agents during the burnishing process 100

101 a) b) c) Fig Surface profilograms showing signs of steel wear in case of rubbing against burnished cast iron and in the presence of: a) SN 150 base oil, b) TITAN CFE 1040 MC engine oil, c) MOTOR LIFE exploitation agent 101

102 a) b) Fig Surface picture illustrating the signs of steel wear in case of cooperation with cast iron and in the presence of: a) SN 150 base oil, b) TITAN CFE 1040 MC engine oil, c) MOTOR LIFE exploitation agent 102