MINIMAL PULSED JET FLUID APPLICATIONS

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1 MINIMAL PULSED JET FLUID APPLICATIONS J.SUNDHAR SINGH PAUL JOSEPH 1 Mr.K.PONPRPAKARAN, M.Tech, 2 M.E (Manufacturing Engineering) Assistant Professor /Mechanical Mahakavi Bharathiyar College of Mahakavi Bharathiyar College of Engineering and Technology Vasudevanallur Engineering and Technology Vasudevanallur jesudossjoseph4@gmail.com ponprapakaran@gmail.com INTRODUCTION The cutting fluid applied during machining process is consider to act as cooling and lubricant agent, hence the cutting temperature can be reduced and the tool life and machined surface finish can be improved. In the intermittent cutting such as grinding operation, especially in high-speed cutting, the large fluctuation of cutting temperature could cause thermal cracks on the cutting edge and subsequently leads to failure of a cutting tool due to edge fracture. Besides, there are serious environmental pollution and waste disposal problems when flood coolants are used. In order to alleviate the above-mentioned negative effects, near-dry machining such as minimal cutting fluid application (MCFA) has been developed. CUTTING FLUIDS IN METAL CUTTING The use of cutting fluid generally causes economy of wheel and it becomes easier to keep tight tolerances and to maintain work piece surface properties without damages. On the other hand, it brings also some problems, like fluid residuals and human diseases. Because of them some alternatives has been sought to minimize or even avoid the use of cutting fluid in machining operations. Some of these alternatives are dry cutting and machining with minimal cutting fluid application (MCFA). CUTTING FLUIDS CLASSIFICATION I. Air II. Water Based Cutting Fluids: a) Water b) Emulsions (soluble oil) c) Chemical solutions (or synthetic fluids) III. Neat Oils: a) Mineral oils b) Fatty oils c) Composed oils d) Extreme pressure oils (EP) e) Multiple use oils FUNCTIONS OF CUTTING FLUID Cutting fluids or widely employed in machining operations to perform three main functions: cooling, lubrication and chip transport from the cutting zone. In addition, they may perform secondary function such as providing temporary protection against oxidation and corrosion (Anshu et al., 2007). The cooling effect of the cutting fluids is an important parameter as it is necessary to decrease the effect of the temperature on cutting tool and machined workk piece. This will lead to longer to life and the dimensional accuracy of the work piece will be improved 106

2 (Eibaradie, 1996).The lubrication effect will cause easy chip flow on the rake face of cutting tool because of low friction co efficient and reduces cutting force and vibration. As a result, better surface roughness would be obtained (De chiffre, 1988). Removal of chips quickly from the cutting tool and the surface of the machined work piece help in protecting the finished surface from scratches. Part of the heat generated is taken away by the chips formed (Thepsonthi et al., 2009). ISSUES RELATED TO LARGE SCALE USE OF CUTTING FLUIDS Besides providing technological benefits, the conventional cutting fluids pose a few major environmental problems (Klocke and Eisenblatter, 1997; NIOSH, 1998). (1) Environmental pollutions due to the chemical break-down of the cutting fluid at high cutting temperature (2) Biologically hazardous to operate due to bacterial growth (Hoff, 2002 ; Sluhan, 1994); (3) requirements of additional system for pumping, local storage, filtration, recycling, chilling and large space because cutting fluids are generally applied in the form of a flood(of the order of 5 lit/min or higher) and (4) water pollution and soil contamination during final disposal. People exposed to large quantities of cutting fluids may have skin contact, inhale mists or vapor, and digestive systems and even swallow mist particles. This may cause dermatitis, problems in the respiratory and digestive systems and even cancer, due to their toxicity (Quinn, 1992). MINIMUM QUANTITY LUBRICATION Minimum quantity lubrication refers to the use of cutting fluids of only a minute amount- typically of a flow rate of 50 to 500 ml/hour which is about three to four orders of magnitude lower than the amount commonly used in flood cooling condition, where, for example, up to 10 liters of fluid can be dispensed per minute. The concept of minimum quantity lubrication, sometimes referred to as near dry lubrication (Klocke and Einesblatter,1999) or micro lubrication (Maclure et al., 2007), has been suggested since a decade ago as a means of addressing the issuse of environmental intrusiveness and occupational hazards associated with the airborne cutting fluid particles on factory shop floors. Minimization of cutting fluid also lead to economical benefits by way of saving lubricant cost and work piece/tools/machine cleaning cycle time. In fact, they already play significant role in a number of practical applications (Heisel and Lutz, 1994; McCabe, 2001) MERITS AND DEMERITS OF MINIMUM QUANTITY LUBRICATION Minimum quantity lubrication technique reduces the consumption of cutting fluids considerably. It facilitates drastic reduction in the tool chip interaction which leads to reduction in cutting force. Reduced tool-chip and tool- work interactions also leads to lower thermal distortion and tool wear. This leads to improvement in surface finish and dimensional accuracy (Dhar et al., 2007). On the other hand, the main limitation of the MQL method is the application of cutting fluid in the form of mist which increase the exposure of hazardous 107

3 aerosols in the shop floor (Anshu et al., 2007).The vapour, mist and smoke generated during the use of MQL in machining can be considered undesirable by products, since they contribute to increase the index of airborne pollutants. This has become a factor for concern, requiring an adequate exhaustion system in the machine tool. Special techniques for transporting chips may be necessary, and productivity may decrease due to the thermal impacts on the machined components. The compressed air lines generate noise levels that usually exceed the legally established limits (Machado & Diniz, 2000). MACHINING WITH MINIMAL FLUID APPLICATION It was reported that the frictional forces between two sliding surfaces can be reduced considerably by rapidly fluctuating the width of the lubricant filled gap separating them (Uzi Landman, 1998). This principle was used in developing a minimal cutting fluid application system by varadarajan et al. in They found that when a high velocity narrow pulsing jet is used instead of a continuous jet is used instead of a continuous jet,better cutting performance can be achieved. This is due to the fact that when a pulsing jet is used, the width of the lubrication filled gap between the tool rake face and chip fluctuates with a frequency equal to the frequency of the pulsing of the fluid jet (Leo et al., 2010). This technique involved cutting fluid particles of very high velocity about 70 m/s (Philip et al., 2000) that tend to penetrate the critical zones rather that float in the air as in most of MQL application. They developed a fluid 108 application system that consisted of a P-4 fuel pump used in compression ignition engines coupled to an infinitely variable electric drive. Cutting fluid was delivered through a fuel nozzle with a specification DNOSD151 and a spray angle of zero degree. This fluid application system had provisions for controlling the rate of fluid application, the frequency of pulsing and also the velocity of fluid particles delivered. A specially formulated cutting fluid (varadarajan et al., 2002) was applied on critical location such as tool-work interface and the tool-chip interface using the cutting fluid application system in the form of a high velocity, narrow pulsed jet. The rate injection of cutting fluid was 2ml/min while the injection and pulsing rate were set at 20Mpa AND 600 Pulse/min respectively.result indicated that the overall performance during minimal cutting fluid application was superior to those during dry turning and conventional wet turning on the base of cutting force, tool life, surface finish, cutting ratio, cutting temperature, and tool-chip contact length. It was found that during minimal fluid application, the rate of fluid was only 0.05% of that used during wet turning and formed a viable alternative to conventional wet turning, as it can be implemented without extensive alterations in the existing facilities on the shop floor (varadarajan et al., 2002). EXPERIMENTAL DESIGN 1. COMPARISON In many fields of study it is hard to reproduce measured results exactly. Comparisons between treatments are much more reproducible and are usually preferable. Often one compares

4 against a standard or traditional treatment that acts as baseline. 2. RANDOMIZATION There is an extensive body of mathematical theory that explores the consequences of making the allocation of units to treatments by means of some random mechanism such as tables of random numbers, or the use of randomization devices such as playing cards or dice. Provided the sample size is adequate, the risks associated with random allocation (such as failing to obtain a representative sample in a survey, or having a serious imbalance in a key characteristic between a treatment group and a control group) are calculable and hence can be managed down to an acceptable level. Random does not mean haphazard, and great care must be taken that appropriate random methods are used. 3. REPLICATION Where measurement is made of a phenomenon that is subject to variation it is important to carry out repeat measurements, so that the variability associated with the phenomenon can be estimated. 4. BLOCKING Blocking is the arrangement of experimental units into groups (blocks) that are similar to one another. Blocking reduces known but irrelevant sources of variation between units and thus allows greater precision in the estimation of the source of variation under study. 5. ORTHOGONALITY Orthogonality concerns the forms of comparison (contrasts) that can be legitimately and efficiently carried out. Contrasts can be represented by vectors and sets of orthogonal contrasts are uncorrelated and independently distributed if the data are normal. Because of this independence, each orthogonal treatment provides different information to the others. If there are T treatments and T-1 orthogonal contrasts, all the information that can be captured from the experiment is obtainable from the set of contrasts. BENEFITS ED enables industrial engineers to study the effects of several variables affecting the response or output of a certain process. ED methods have wide potential application in the engineering design and development stages. It is the strategy of the management in today s competitive world market to develop products and processes insensitive to various source of variation using ED. The potential applications of ED in industries are: 1. Reducing product and process design and development time; 2. Studying the behaviour of a process over a wide range of operating conditions; 3. Minimizing the effect of variations in manufacturing conditions; 4. Understanding the process under study and thereby improving its performing; 5. Increasing process productivity by reducing scrap, rework etc.; 6. Improving the process yield and stability of a non-going manufacturing process; 7. Making products insensitive to environmental variations such as relative humidity, vibration, shock and so on; 109

5 8. Studying the relationship between a set of independent process variables (i.e., process parameters) and the output (i.e., response). SURFACE FINISH The fatigue life, bearing properties and wear qualities of any component of a machine have direct relation with its surface properties. Surface finish is an important parameter during machining in industries. The smoothness of a surface is determined by the surface finish. If the surface produced is rough then it indicates low surface finish which will affect the quality of part. SURFACE TEXTURE It is the regular or irregular surface spacing which tend to form a pattern on the surface. Three types of surface textures 1. Primary texture (roughness) 2. Secondary texture (waviness) 3. Lay SURFACE FINISH PARAMETERS Surface finish could be specified in many different parameters. Due to the need for different parameters in a wide variety of machining operations, a large number of newly developed surface roughness parameters were developed. They are 1. Roughness average (Ra) 2. Root mean square roughness (Rq) 3. Maximum peak to valley roughness height (Rmax) In order to get good surface finish the Ra value should be kept minimum. Surface roughness is measured using a perthometer. PARAMETER CHART Input variable Process Output variable Work Dept Press Freq Direc Rate Com REFERENCE W1, W2, W3 D1, D2, Surfa Cutti 1. João Fernando Gomes de Oliveira, Nucleus of Advanced Manufacturing, Dept. of Production Engineering, University of São Paulo, Brazil. Vegetable based cutting fluid an environmental alternative to grinding process. Had done many National and International Conferences and published many papers in journals. 2. P. R. Aguiar, UNESP - Universidade Estadual Paulista Bauru Department of Mechanical Engineering. Had done many National and International Conferences and published many papers in journals. 110