CONTENTS THEORY OF LUBRICATION. LUBRICANT TYPES Straight Oils Soluble Oils Semi-synthetics Synthetics

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Jerome Grant
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3 CONTENTS THEORY OF LUBRICATION LUBRICANT TYPES Straight Oils Soluble Oils Semi-synthetics Synthetics LUBRICANT ADDITIVES Emulsifiers Extreme Pressure andlor Lubricity Agents Buffers Corrosion Inhibitors Antifoamants Demulsifiers Preservatives MACHINING (CHIP MAKING) OPERATIONS GRACE METALWORKING FLUIDS FLUID SELECTION GUIDE PHYSICAL TESTING A. Cutting Oils 6. Soluble Oils, Semi-synthetics, Synthetics C. Sump Fluids MISCELLANEOUS INFORMATION CHEMICAL HANDLING AND STORAGE

5 Fi THEORY OF LUBRICATION EFFORT b b b ing-a INTERFERANCE When one rough metal block is pushed across a second rough metal block, microscopic peaks on the block surface interfere with the sliding action and cause a form of solid friction. Sliding two smooth surfaces against each other causes weld- second form of solid friction. Friction can be reduced by employing smooth surfaces that keep interference friction low, and by choosing dissimilar metals that will reduce metalto-metal welding. Fricfion forces refard sliding! Surfaces designed to allow relative movement between components while providing support, or guiding movements, are subject to friction and wear. Wear can be essentially eliminated and friction can be controlled to the point where it presents little problem. Hydrodynamic lubrication shows a continuous film of fluid lubricant separating the surfaces; the relative surface movement has created an oil wedge that suppolts the upper component. The lubricant used should have the proper viscosity, or resistance to flow, so it has sufficient "body or "thickness" to resist being squeezed-out while being thin enough to prevent excessive fluid friction. Looking at a simple journal-bearing, we see that JOUrnal rotation causes the formation Of a lubricant wedge just like the flat surfaces shown earlier. The pressure generated by this wedge reaches a maximum at the point where the lubricant film is thinnest; pressure is lowest at the bearing edges and at the bearing inlets and outlets. All full-time lubricants involve the lubricant wedge and pressure build-up. Some surfaces are so highly loaded that the lubricant film is interrupted, requiring "extreme pressure" (EP) lubrication. Mixed film lubrication, involving monomolecular films and frequent metal- B ROTATION Lubricant wedgessupporf bearing pressures. Lubricant films separate mefa/sufiaces. to-metal contact, generally provides low-friction sliding and controlled wear of the metal. As this film is constantly removed by the continuing contact, thesurfaces are eaten away, but at a tolerable rate, avoiding catastrophic wear that would occur with a non-ep lube. 1

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7 LUBRICANT TYPES There are four basic types of metalworking lubricants used in metal forming and metal cutting operations. They include: Straight Oils, Soluble Oils, Semisynthetics and Synthetics. STRAIGHT OILS Straight oils have been around the longest. They include mineral oils, napthenic and paraffinic oils and vegetable oils such as lard and castor oil. To the baseoils, additives are often blended to improve EP, anti-weld, etc. They typically offer excellent lubricating properties with only minimal heat-transfer or "cooling." SOLUBLE OILS Soluble oils were developed to offer the lubricating properties of oils with the cooling properties of water. Soluble oils perform well on ferrous and non-ferrous metal. One drawback of soluble oils is their tendency for biodegradation. SEMI-SYNTHETICS Semi-synthetics are basically water solutions with small amounts of oil microemulsified for improved lubricity while offering the cooling properties and cleanliness of synthetics. SYNTHETICS Synthetics are non-petroleum-based materials which offer varying degrees of lubricity with excellent cooling and cleanliness. Synthetics are preferred because they are biodegradeable, less likely to become rancid and generally do not cause dermatitis. They also make filtering and recycling an easier possibility. 3

8 ~ L UBRICANT ADDITIVES Most high quality lubricants contain additives. Some of the more common additives, the reason for their use, their function and the way they enhance performance include: TYPE Emulsifiers REASON FOR USE HOW THEY WORK ADVERSE EFFECTS Hold lubricant and water Polar-type compounds Reduces oxidation retogether in soluble oils line up at the lubdwater sistance. Fights activity and semi-synthetics. interfaces providing of anti-wear, EP, oilisolubility bridges between the fluid and water. ness, anti-rust and anti-foam agents. May cause seal swell. - Extreme Pressure (EP) and/or Lubricity Agents ph/alkalinity Buffers Corrosion Inhibitors ~~~~ Modify friction, reduce Form bonds with rubbing Promote oil oxidation, wear, prevent galling surfaces that provide foaming, emulsion and seizing. supplemental "wear tendencies. Thermal surfaces." The key is stability is weakened. "control," not elimination. Maintain sufficient Larger amounts of alka- Too high ph can alkalinity to retard biode- line materials having a low cause skin irritation gradation and corrosion. pk, value require large and soft metal attack. amounts of acid contami- Too low ph results in inants or decomposition bioactivity and rust. to neutralize them. Prevent oxidation of Polar-type compounds Reduce oxidation resismachine surfaces, tools react with, or are absorb- tance in lube, tendency and work pieces. ed on, metal surfaces. to emulsify, may leave sticky residues. Antifoamants Ensure rapid collapse of Attracted to lube/air inter- Silicone types promote large air bubbles. Prevent faces; lowers surface air entrapment. Others excessive lubricant oxida- tension of air bubbles increase emulsion tention. causing quick break. dency. Demulsifiers Preservatives Encourage rejection of React with polar emulsi- Demulsification must tramp oils. fiers at oillwater inter- be controlled to avoid face, breaking solubility breaking the solubility - bridge between oil and water causing separation. bridge between the lube and the water. Prohibit or retard micro- Provides an environment Overconcentration bial growth. toxic to microbes. can cause irritation to humans. - 4

9 LIMITS OF ACTIVITY Different emulsifier packages must be used for each base lube. TYPICAL COMPOUNDS Metal sulfonates, glycols, ethoxylated phenols, alcohols or acids, napthenic acids. Heat (metal-to-metal contact) is needed. Notable properties are obtained with one EP additive. Affected by some water sources, concentration fluctuation and contaminants. OilinessIfatty acids, amides, esters & soaps. Antiwear=phosphates, lead, sulfur, chlorine, polyalkaline glycols. Amines, caustics, carbonates. Most require direct contact for effectiveness. They deplete and must be replaced. Some lube additives or contaminants render anti-foams ineffective. Organics, soaps, carboxylates, sulfonates, phosphate, organic acids and esters, molybdates and borates. Silicone polymers, methyl acrylic polymers, stearates. Some weakly emulsified lube may also be separated out. Avoid over treatment. Cationics, polymers. They're consumed or decomposed. Must be replenished regularly. Most work at ph Resistant strain can develop if undertreated. Triazines, omadine, phenol, oxizolidines, imidazolines. 5

10 MACHINING (CHIP MAKING) OPERATIONS Broaching Cold Heading Drilling Extruding Grinding Honing Punching Roll Forming Stamping Tapping Threading Turning A machining process where a cutting tool having multiple transverse cutting edges is pushed or pulled through a hole or over a surface to remove metal by axial cutting. A high speed method of gathering metal in certain sections along lengths of bar, rod or wire by causing the metal to flow between the dies without preheating the metal. This process is used to make fasteners, ie. bolts, screws, nails, etc. The initial operation forms the head which is the essential part of the fastener. An efficient and economical method of cutting a hole in solid metal. A drill for cutting metal is a rotary end-cutting tool with one or more flutes to promote chip removal and the admission of cutting fluid. A forming technique where steady compressive forces on unheated steel cause its controlled flow into a die. The removal of small chips of metal from the workpiece by the mechanical action of irregularly shaped grains imbedded into a grinding wheel. An abrasive machining process designed to improve bore geometry and surface finish. The shearing of holes in sheet metal with a punch and die. The process of forming strip metal into channels, moldings, architectural sections and similar parts through the use of dies or forming roles. The process used to cut lines of letters, figures and decorations on smooth metal surfaces. The impact of a punch with comparatively sharp projecting outlines impresses the characters into the surface of the metal. Stamping is also used when referring to various press-forming operations, ie. coining, embossing, blanking and pressing. The machining process for making internal threads. A tap is a cylindrical or conical thread-cutting tool having threads of a desired form on the periphery. Combining rotary with axial motion, the tap cuts or forms the internal thread. Cutting external threads on cylindrical or tapered surfaces. Generating external surfaces of revolution by the action of a cutting tool on a rotating workpiece, usually in a lathe. 6

11 GRACE METAL WORKING FLUIDS A. Daracool740 Light to medium duty synthetic for ferrous machining and grinding (No CI, P, S). B. Daracool745 C. Daracool N733 D. Daracool706LF E. Daracool28E-3 Medium to heavy duty synthetic for ferrous and limited non-ferrous machining and grinding (No CI, P, S). Heavy duty synthetic for ferrous and non-ferrous machining and grinding (No CI, P, S). Universal synthetic machining fluid for aluminum, copper, steel, stainless and titanium (No CI, P, S). Semi-synthetic for multimetal machining and grinding (No CI, P, S). 7

12 I FLUID SELECTION GUIDE I FERROUS AND NON-FERROUS METALS Machining Aluminum Coolant Copper, Manganese Bronze, Gun Metal Coolant BrassIBronze Cast Malleable, No Grey Iron, Zinc Coolant Nickel, Hi Alloy, 1000 Steel, Inconel, Monel. Stainless Steel Coolant Milling t Screw Machining (High Speed) Screw Machining Deep Drilling Gear Cutting Tapping Threading Internal Broaching External Broaching I I I I D I I I I A = Daracool740 B = Datacool745 C = Daracool N-733 D = Daracool706LF I 1 50 Rockwell C and Below ~ Grinding: Surface Centerless Threading FormlCrush Blanchard Style I.D. O.D. Low Stock HI Stock Removal - Removal A B C-D A A A A A D D 8

13 BC D D D D Low Stock Removal A Hi Stock Removal A 9

14 PHYSICAL r mm The common tests used to check lubricant quality and finished lubricant properties include: A. Cutting Oils Property Physical Significance Chemical How Measured Units Viscosity The force required None to shear the fluid. Fluid flowing through an orifice. Saybolt (sus); Centistokes; Centipoise; Zahn Viscosity Index (VI) The change of viscosity Lube VI varies with Ratio of vis at two with temperature. base composition. temps. (usually 100/ 210 F). Specific Gravity Weight per unit volume. Lube gravity varies with Hydrometer; base composition. Picnometer Flash Point Related to oil vapor Lower explosive limit of Passing a lighted flame pressure. an oil/air mix. over a liquid heated at a constant rate, recording the first surface flash. Non-dimensional API degree; Sp. Gr.; Ib/gal. "F Cleveland Open Cup (COC); Tag Closed Cup (TCC); Pensky-Mattins Closed Cup (PMCC) Falex Bearing load and None resulting wear produced by extreme pressure forces. A prescribed load is applied to a metal pin, allowing wear to be measured. PSI Load; Torque; Finish 10

15 PHYSICAL TESTING 6. Soluble Oils, Semi-synthetic, Synthetics Property Physical Significance Chemical How Measured units Solubility Solution stability when diluted with different water sources. Emulsion properties and water conditioning properties. Graduated cylinder, visual after 24 hours. Good, fair, poor rating. PH Acidity or alkalinity of a solution. Acid, base buffering. Meter, paper Refractive Index The velocity of light in air: velocity of light in coolant fluid ratio. Coolant concentration. Refractometer. "Brix Foam High turbulance None Blender agitation, Inches initial foam; systems require low collapse rate in foaming properties. seconds. Swarf Effect Coolant ability to sink swarf so it can be carried out on a conveyor or shoveled out. None Blender agitation. Visual observationfloat or sink. Demulsification Coolant ability to reject tramd oil. Emulsion properties, oil rejection. Blender agitation. Visual rejection or emulsification. Corrosion Inhibition Coolant ability to retard metal oxidation of the machine table, tool and workpiece. Rust inhibitor effectiveness. Cast Iron Chip Test, Sandwich and Immersion tests. Rate: Excellent, Good, Fair and Poor. Falex Same as under A Specific Gravity Same as under A 11

16 PHYSlCAL TESTING C. Sump Fluids DH Concentration Free Oil Total Oil Sediment Conductivity Corrosion Inhibition An indication of how acid or alkaline the sump solution is on a scale of For coolant sumps it is important to have ph as high as possible to retard microbial growth, yet low enough so it will not harm operator hands or attack soft metal such as aluminum. Method: ph meter or ph paper. Recommended range = Treatment: Daraguard 88. A measure of product in the sump fluid. Although the laboratory uses refractive index, titration, FTlR and Hyamine titration depending on the type of solution involved, refractometer measurement is most convenient for field use. Recommended range = 58% (may vary from 3% in some grinders to 18% for some tapping operations). Note: Alkalinity buffers, corrosion inhibitors and preservaties are formulated in for optimum performance at 5.8% dilutions. Low concentrations will have substandard protection whereas high concentrations may result in operator irritation. Also known as tramp oil, this is all oil not emulsified or weakly emulsified in the sump fluid. Free oil floats on the coolant surface and should be kept to a minimum by skimming, suction or filtration. Method: Graduated cylinder or centrifugation. Recommended limits: Less than 3%. Treatment: Skim, suction, filter. To enhance demulsification of tramp oil use Daraguard CP according to directions. The total amount of oil in the sump including coolant (if petroleum based) and tramp oil-both emulsified and not emulsified. Method: Acid splitlcentrifugation or acid splitlhot water bath. Recommendation: Keep oil contamination (not contributed by the coolant) to a minimum. Treatment: Daraguard CP. The amount of particulate matter suspended in the coolant. High level can adversely affect finish. Method: Centrifiugation or Graduated Cylinder. Rec ommendation: Keep to a minimum-less than 1%. Treatment: Filtration. A measure of electrolyte material in the sump. This material can cause corrosion and can also be a food source for microbes. Method: Conductivity Meter. Recommended Range: umhos/cm. Treatment: Filter or bleed off at 10.25%. Same as under B. Method: Cast Iron Chip Test. Recommended Range: Excellent to Fair-watch; Poor-treat. Treatment: Adjust concentration to 5-8 %; add Daracool

17 BacteridMold Color Microbial activity in a sump fluid. Method: Bio paddles. Recommended Range: Bacteria-less than 1 06, mold (fungudyeast) nil. Treatment: Adjust concentration with product or water. Adjust ph with Daraguard 88. Add Olin Triadine 10 at 2mllgal. (repeat in hrs as needed.) Color additives are added to concentrates as part of the formulation for aesthetic reasons. Once in the sump, the color of the working fluid allows some conclusions related to its condition: Microemulsions or Solutions Fresh prepared: Transparent or slightly opalescent In operation: Opalescent (tramp-oil) Brownish (rust from iron particles) Emulsions White or white-blue Sulfurized compounds are often chocolate or tan. Yellowish (tramp oil) Grey-grey/brown (abrasives) Grey-brown (rust from iron particles) Grey-blue (bacteria) Smell The smell of a working fluid compared to the smell of a freshly prepared fluid can give indication of changes during its use: Odor cheese, musty putrid, rotten paint (vinyl acetate) ammonia other Cause fungus/mold bacteria some kind of bacteria some kind of bacteria possible contamination by extraneous chemicals 13

18 MISCELLANEOUS INFORMATION Misting Synthetic solutions have reduced tendency to be misted, whether by mechanical devices, by spray or fogging nozzles, or impingement onto rapidly moving surfaces due to viscoelasticity evidenced by a tendency for the liquid to form long filaments rather than round droplets. This also enhances their filterability. 14

19 CHEMICAL HANDLING AND STORAGE Omadine containing lubricants and additives are packaged in plastic or lined steel containers to avoid formation and precipitation of ferric omadine in the drum. All triazine containing lubricants and additives must be stored at temperatures less than 110 F. The biocide can start to decompose at temperatures above 11 5 F. For best results store all lubricants out of direct sunlight at temperatures between F. If contents freeze, ensure complete thaw and remix before any contents are removed from the container. Any unused lubricant should be stored in a manner to minimize contamination, loss, misapplication or weather hazard. For best results use only Grace Metalworking Fluids according to product sheet directions. 15

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