Cutting Fluid Selection and Process Controls for the Gear Manufacturing Industry

BACK TO' BAS,i'CS ••• ------Cutting Fluid Selection and Process Controls for the Gear Manufacturing Industry

Ike Tripp, Jr. Etna Products, Inc. Chagrin Falls, Ohio

Introduction a helical thread corresponding to the The last decade has been a period of thread of a worm. As the hob rotates in far-reaching change for the metal work- timed relationship with the gear blank, ing industry. The effect of higher lubri- each row of teeth successively cuts the cant costs, technical advances in machine next portion of the gear tooth-space. The design and increasing competition are cutting action is continuous in one direc- making it essential that manufacturers of tion until the gear is completed. gears pay more attention to testing, Conversely, the gear shaping method selecting and controlling cutting fluid operates on the principle of two gears systems. lubricant costs are not a large Fig. 1- Gear hcbbing rolling in mesh. In molding generating percentage of the process cost relative to processes, a gear-like cutter called a items such as raw materials, equipment shaper tool is rotated and reciprocated and labor, and this small relative cost has in the correct ratio with a gear blank. tended to reduce the economic incentive The cutting tool used in gear hobbing (See Fig. 2.) The gear blank rotates while to evaluate and to change cutting fluids. is called the "hob". (See Fig. 1.) The ma- the cutter rotates and reciprocates to pro- Nevertheless, one of the largest factors jority of hobs are cylindrical in form and vide the cutting action. The shaper only in lost production during gear manufac- greater in length than in diameter. The cuts in one direction so relief is provided turing is excess tool wear, tool failure and cutting teeth on the hob are arranged in for the return stroke. subsequent product rejection. In this day and age of economic war of survival, it has become essential to consider and to evaluate new cutting fluids with an eye towards increasing tool life. improving overall productivity and product quality and lowering costs.

Gear Cutting and Finishing A wide variety of manufacturing techniques are used to manufacture gears. Specifically, this article addresses the selection and process controls for the fluids used for gear hobbing, gear shaping and hard gear finishing.

AUTHOR:

MR. lKE TRIPP, JR. IS vice presiden: and gfflerai manager of £fnIl Products. Inc He has been with the company since 1974. and is the auihor of over 30 techmcal papers on industrial metalworking compounds He IS a member of Fig. 2.-Gear Shaping ASLE. ASM. the Wire Association and SME.

.July/August 1987 37 Hard gear finishing is a process which a two dimensional view of meta] cutting. the environment of deformation. uses either generative grindmg or fanned Of the heat generated, about two-thirds wheel grinding to finish the flanks of is expended in sticking friction in the Types of Cutting Fluids parallel axis spur or helical gear~ after shearing zone, and one-third is expended A number of gear cutting and grinding they have been hardened by heat treat- in sliding friction at. the tool/chip and fluids meet the requirement of providing ment, The hard gear finishing technique tool/flank interfaces. The action of the adequate lubrication. This range ,of usua1ly removes ,.0021 .0025" from each fluid is ito [ower the heat generated in availability was not always present, as side of the gear teeth, these two zones, and the lubricant por- lubricant research and development was In the form grinding process, the tion of the fluid reduces friction at the oncea black art with few practitioners, grinding wheel has a profile mirroring the 'tool/chip andtool/flank interface. Now, through scientific research and the tooth space between two adjacent gear A fluid used in hard gear grinding cooperative efforts of vendors and teeth. As the formed wheel moves be- operation functions very much like a cut- buyers, lubricant development, applica- tween the teeth of the gear, it removes ting fluid, but there are very pronounced tion and behavior is becoming a 'science. excess stock. differenoes between the dynamics of the For the purposes of this article, There are several types of machines processes, Gear grinding involves lubricating fluids have been classified as and tool configurations used in the negative rake tool angles and random either oil-based or water emulsifiable. generative grinding process. These pro- orientation of cutting surfaces. The Oil-Based Fluids.Oil-based fluids are cesses either use a cutting tool designed temperatures and surface feeds are also used for gear cutting and hard gear as at. spur or helical gear, which grinds the higher. Most of the heat of deformation finishing where water emulsifiable com- gear using the shaving or gear shaping is carried into the workpiece soa gear pounds do not have the film strength or principle, ora. shaper cutter tool that uses grinding fluid must act to reduce grinding wetabili.ty to produce acceptable tool life a skiving principle or a worm type forces, which reduces heat generation. or surface finish. Oil-based fluids are .finishing tool similar to a worm type gear The cooling function of the fluid is con- gen rally compounded with the follow- grinding wheel. sidered secondary, but it is still impor- ing items: Recently, grinding wheels plated with tant to the success of a hard gear 1, Mineral oils, either napthenic grade cubic boron nitride (CBN) have been finishing operation, that have a saturated ring type used in place of dressable, conventional Fluids used for gear cutting and grind- structure, or paraffinic grade, abrasive grinding wheels. CBN is a syn- ing must exhibit a number of other pro- which have a straight or branched thetic crystalline material that is very perties. They must not be adverselyaf- chain structure. wear resistant, and it has pronounced fected by metallic contaminants or tramp cutting edges because of its cubic shape. oils that can enter a lubrication system. .2. Mineral oils blended with polar ad- CBN applied by the electroplating pro- They must not leave excessive resldue on ditives, as the oils themselves ..are cess is considered the best for form gear the surface of a gear to be subsequently nonpolar. The function of the polar grinding. CBN is very expensive, and its heat treated, and they should aid in the additive is to affect the wetting of use dictates the need for improved production of a gear that has, the desired the metal surface at the coolants delivered at higher flow rates properties - surface finish,runout, etc. tool/workpiece interface by reduc- than used with conventional wheels. The study of the subject of wear being the interfacial tension between tween two materials in motion relative the mineral oi1 carrier and the gear Th.eory of Lubrication to ·oneanother is very complex, A blank. A polar additive has a sort The aim of fluids used in cutting and number 'of parameters influence wear. of magnetism for the metal due to grinding operations is to provide cooling Some of these include the shape of the its molecular structure. and lubrication. contacting bodies, applied load, relative Polar active additives come from Gear hobbing and gear shaping are velocity between the surfaces, surface several. sources. Animal. fats and oils are metal. cutting operations that generate roughness, the elastic and plastic proper- derived by rendering the f.atty tissues of chips. More than 97% of the cutting ties of the contacting materials (par- animals such as cattle, pigs and sheep. work appears as heat. Fig. 3 illustrates ticularly those of the surface layers), and Vegetable fats and oils are derived by

fig. 3- Two-dimensional metal cutting diagram Table 1 - Coolants Grades by Contents

FERROUS NON-FERROUS

2 SlVHUR ANDIOR HEAVY DUTY 10.1 CHL.ORINE WITH~FAT SHEAR ANGLE

FAT SlMSYNTHETIC SEE MEDIUM DUTY SEE MEDIUM DUTY

WORKPIECE SYNTHETIC NEW E P ADDITIVES NEW E P ADDITIVES

38 Gear Tecl1nology crushing and rendering the fruits of active agents and chemicals used in the The formulation of a comme:rcially ac- plants such as palm or coconut trees. formulation of the product are small ceptable product depends on in- Marine fats and oils are derived from enough to transmit almost all incident vestigating hu_ndredS ofemul ifiers which crushing and rendering the fatty tissues light. True synthetics contain no mineral can be classed as: of fish. oil, and each component used in the 1. Anionic- These are emulsifiers The mineral oils and polaradditives fonnulation is soluble in water on its whose electrolytic properties are are then often compounded with sup- own. The particles are smaller than H based on the formation of anionic plemental polar additives, which act as .00000000 in diameter and cannot be ions. Examples include sulfonated extreme pressure agents. The primary ex- viewed under any microscope. polyester or sulfonated castor oils. treme pressure agents utilized are sulfur. GeneraUy most .of th water chlorine or phosphorous. When sub- emulsifiable fluids available contain a 2. Cationic - These are emulsi iers jected to the elevated temper.atUf'esat the napthenic oil made soluble through the whose electrolytiC properttes are tool/workpiece interface, these 'extreme use of emulsifiers or surface-active based on the Iormation of cationic pressure additives react to form an agents. ions. Examples .indude organic sal,t5 organo-metallic film which minimizes friction and lowers heat generation.

Water Emulsifiable Fluids. Water emulsifiable fluids are defined as those where wate:r is the continuous phase .. Basically. water emulsifiable fluids com- bine the cooling properties of water with the lubricating properties of anand/or various chemicals. Over the years, a good deal of jargon has evolved in the industry to describe water emulsifiable fluids for the gear manubcturing industry, Water miscible er ,emulsifiable lubricants are available in. many fonns. They can be classed based on their components, performances and appearance. Water soluble oils, sometimes called. emulsiens or walter miscible fluids, are made by blending oil, either paraffinic Dr napthenic, with emulsifying agents. 5.0 the oil forms small droplets called micells, which range in size from .0002" to 0.00008" in diameter when mixed with water. The emulsion appears milky as the particles of oil reflect almost all ind~ dent light, making them .opaque. Solu- ble oils are subdivided into light, medium and heavy grades, dependmg on the components used in their formulation. (See Table 1.) Semi-synthetic fluids are mixtures .of emulsifiers and surface-active chemicals and have a low eil content of 10 % to 25%. A typical soluble ell contains 45% to 70% oil, Because a semi-synthetic con- tainsless on than a water soluble lubricant, it can vary from being translucent Hanslord Manufactunng Corp. to completely dear. as the micells range 31111 Winton Road South n Rochester, New York 14623 in size between .000000 and .000001" in ,(71!6) 427-0660 diameter. They can only be seen under an electron microscope. Synthetic solutions are almost always CIRCLE A-15 ON READER REPLY CARD dear. as the particle size of the surface-

..lllyIAugust 1987 3'9 Table 2 or polyethoxylaredamines. for screening the wi.de variety of 'candidate Fluids must be developed. These 3. Non-ionic- These emulsifiers do compounds vary greatly in their not. behave as electrolytes and do IRIIIOIIII 4IC'IWE a M:INl chemical and physical properties, and $lOW 8WUII not ionize in water. Examples in- Ifllil .... because of the critical need for optimum Ml'fIIII... clude ethoxylated vegetable oils. tool life, any variation in the physical SMIITY 1IfWTAI. Sllrtac,e-active or polar extreme and chemical properties of a given fluid WIIIIIII8 0PfIIA1l0II pressure additives are also added to the becomes important. To assure the I IMC1M ~ IIIC1M Iorrnulauon of a water emulsifiable fluid reliability of a given fluid, many lubri- to wet out and to penetrate the cant manufacturers perform a number of MGt.,otI tool Iworkpiece interlace. These agen ts, tests to assess its physical. chemical, _SPHD MJ ...... - CI/Jl1IIII .~ reduce the interfacial tension between the metallurgical and humancompatibiUty. water, lubricant and the metal. The polar These tests yield data that ean be used 0fRIIWY1If additives have an affinity for the metal to, screen fluids prior to in-plant testing. 11&- -..rt substrate and form an organa-metallic --- film which provides lubrication by Physical L.abo~atory Tests. These lab reducing friction at the tool/workpiece tests are designed to simulate as closely interface. There are a variety of oils, fats, as possible actual production conditions waxes and synthetic polar additives such and to generate data as to' the reliability as esters or complex. alcohols used as of a fluid under actual conditions of use. b. Tests have indicated tha't it is surface-active agents .. 1. Stability of a neat oil. The product possible for sulfur used in rutting should be stable under normal and fluids to, react with titanium Fluid Selection. A number of factors af- adverse conditions. The following nitride coatings or CBN fect the type of fluid used in a gear hob- tests can point out stability prob- coatings, causing erosion of the bing, gear shaping or hard gear finishing lems: Place an ,eight ounce sample coating and thus lowering tool. operation. The primary criteria for selec- in a dosed sample bottle and allow life. tion of material, which determines i't to stand 21 to 30 days at ambient machinability, speed and severity of temperature. Monitor for any 3. Load carrying properties. The Four operation and the acceptability of a fluid, changes; i.e., separation, gelling. To Ball Test and the Falex Test were are alJ interrelated. Table 2 illustrates the test the eHects of freezing and thaw- developed to determine the load additives utilized when severity is corn- ing, put an eight ounce sample of carryLng properties of euttlngand pared to difficulty of machinability. the neat oil in a dosed container grinding fluids. The primary fluids used on CBN and place the sample in a freezer for a. Shell Four Ball EP J:est ASTM grinding of hard gears are oil-based 24 hours. Thaw, then refreeze for 0-2596 and D-2783 .. The She[J because grinding wheel wear has been 24 hours and thaw again. Examine Four Ball Test consists of four found to be related to the temperature of the neat oil for changes; i.e., 112" diameter balls arranged in the wheel matrix ..As the temperature of separation, sedimentation. the form of an equilateral the wheel matrix increases, the weal' of tetrahedron. The lower three the wheel increases. Testing with both 2. Nonferrous corrosion, One test for halls are held immovably in a oil-based and water-based Ilcids has nonferrous corrosion is to place a 30 ml sample of the neat fluid in a damping pot to form a cradle in shown that oil-based fluids provided bet- 100 ml beaker and then to put a which the fourth ball is caused ter lubricity and lower temperatures of to, rotate about a vertical axis. the wheel matrix. properly abraded and cleaned cop- The fluid under test is held in the Another factor that influences grinding per strip in the beaker, heat to 220 damping pot and covers the area wheel. life is the cleanliness of the oil- .F for three hours and check for of contact of the four balls. Dur- based lubricant. The hard gear finishing staining on the strip. The eff,ect of a rutting and grinding the test, scars are formed on process generates very fine swart which the surface of the stationary must be removed so as to' maximize ing fluid compound on the gear balls, and the diameter of the wheel lif,e and improve surface finish. being manufactured must be as- scars depends upon the load, The most effective method of filtering a sessed for two reasons. duration, speed of rotation and grinding oil-based Huid is a horizontal a. Some of the 'extreme pressure type of fluid. The scars aile plate pre-coat Filter. The filtering agents, such as sulfur, used in measured by a microscope hav- capability of a typical pre-coat filter is these compounds might corrode ing a calibrated grid at the com- between one and three microns, the gear 'or the nonferrous parts like valve pipes and bearings in pletion of the test. Testing and Process Controls the actual manufacturing b. An alternative to, the Four Ball Selecting the appropriate lubricant for machine, as well as possibly 'test, the Falex test machine pro- gear hob bing, gear shaping or hard gear adversely affecting the finished vides a rapid means of measur- finishing is very difficult. Effective tests gear. ing the load 'carrying capacities and wear properties of a given rapid rusting of ferrous parts unless 0.01 % by volume can cause a prob- fluid. The test consists of the oils are adequately treated with lem because it turns to steam at the rotating a. test pin between two inhibitor compounds. The ASTM tool/workpiece interface, and this loaded journal V-blocks im- D-665 rust test is designed to steam blanket minimizes lubricity. mersed in the fluid sample. The measure the ability of industria'! oils The level.of solids can be controlled test pin is driven by a 113 hp to prevent rust. through filtration, and the level of motor at .290 rpm, and 'the [our- solids and water should be checked Process Controls for nalsare loaded against the test periodically to monitor the condi- Oil.-Based Compounds pin by means ofa spring gauge tion of the oil. micrometer. The Falex machine There are many variables, such as s. Acid number - In oil-based fluids is also an extreme pressure tester, feeds, speeds and operator expertise, in- the acid number denotes the level and can be used to conduct a volved in the gear hob bing, gear shap- of acid-type components that in- wear test, ASTM D-2670, to ing and hard gear finishing process; fluence the behavior of the fluid. assess the effectiveness of a given therefore, it follows that any variation When oil. is oxidized, the acid fluid. in the effectiveness of a given lubricating number increases and adverse fluid will become important to overall. 4. Cast iron corrosion. This test is im- chemical reactions, such as the for- productivity and profitability. To assure portant as the fluid must be tested mation of insoluble metallic soaps, the long term reliability of each com- to assess its effect on the interior 'can occur. Therefore, it is impor- pound, i.tis important to monitor and to ferrous parts of 'the gear cutting or tant to monitor the acid number. maintain certain controls for straight oil grinding machine. A chip test or a compounds. 6. Additive content - Th additives Q-Panel test conducted with a used to blend gear cutrlng and Cleveland Condensing Humidity 1. Handling and storage - Oils grinding fluids are depleted through Cabinet can assess the effect of a should be stored at ambient use; therefore, additive levels must given compound. temperature. If the oil is frozen, it be carefully monitored. The load should be thawed and mixed prior bearing capacity of a fluid is related Chemica/.and Metallurgical Compatibil- to use. to 'the concentration of the ity. A candidate fluid must also be con- 2. Temperature - It is important to additives. sidered from a chemical and maintain the temperature of an 011- metallurgical standpoint. The gear hob- 7. Record keeping - A logbook based fluid at ambient temperature; bing and gear shaping process and subse- should be maintained to record 'the i.e., approximately 65° - 75°F, or quent hard gear finishing process involve test data. This logbook can be used at least to. maintain the temperature the exposure of unprotected, unoxidized to track the performance of the oil below USaF if it is not possible to metal surfaces to the chemical com- in a system. keep it lower. ponents of a lubricating fluid at elevated Quality Control of th« Operating temperatures and pressures, Due to the Excessive heat causes oxidation Emulsified Fluid. To effectively maintain elev-ated temperature and pressure, it is reactions which show up as sludge an operating emulsifiable Iluid, the important to assess the effects of those formation, varnish formation and operator is advised to observe several reactions prior to in-plant testing. the formation of acidic by-products which also cause corrosion. These basic points. 1. Turbine oil oxidation test ASTM by-products minimize lubricity. Ex- 1. Handling and storage - A good D-943. This test predicts the cessive oxidation can be controlled emulsion starts with good storage oxidation life of hydraulic oil, tur- by maintaining correct operating conditions for 'the neat oil. The bine oil, and metalworking oils .. temperatures. complex chemical make up of most The test depends upon the catalytic 3. Viscosity - The viscosity of a emulsifiable fluids requires the effect of metals at elevated straight oil can change with time storage of neat oil al ambient 'temperatures in the presence' of because of a number of factors, temperatures. If the neat oil is water to accelerate the rate of ox- such as tramp oil leaking into the frozen, it should be allowed to .idation. The degree of oxidation is system or chemical reactions in the return to ambient temperature prior determined by an increase in the oil due to heat and oxidation. to. mixing the emulsion. acid number of the oil Viscosity is an important indication 2. Mixing - As a general rule, most 2. Rotary bomb oxidation test ASTM of the condition of the oil. emulsifiable fluidsal'e added to D-2272. The rotary bomb oxidation 4. Water and solids content - Proper water in the reservoir while 'test is a more' rapid method of com- filtration is necessary for good tool agitating to form the emulsion, but paring the oxidation life of fluids in life and product quality, as excess the supplier should always be con- similar formulations. metal fines can plug supply lines or sulted forcorr,ec't mixing 3. Turbine oil rust test ASTM 0-665. catalyze chemical reactions to form. instructions. Contamination of gear manufactur- sludge or varnish .. 3. Wat,er source and composition - ing fluids with water can produce Wa't,er at quantities greater than Because water is a major compo-

Ju'lyj August 1981 41 nent of an operating emulsifiable emulsifier package, which af- portant 'to filter the emulsion and fluid, its quality plays a large part fects stability. The higher extend its useful life. in operating effectiveness, The life temperature also does not 9. Foaming - Care must be taken to of the emulsion in the reservoir, allow for efficient heat maintain pump seals so as to foam characteristics, tool life and transfer at the tool/workpiece minimize pump cavitation and product quality are all influenced interface. This lack of cooling reduce foam. Excessive Ioam by the quality of the water. Make- can result in poor tool life and minimizes effective cooling and up water should he as pure as possi- product quality, and oxida- lubrication at the tool/workpiece ble, Distilled or deionized water is tion of the oil phase of the interface. idea" as hard water, which is con- emulsion. As a corollary to 10. Record keeping - A log book taminated with minerals and dis- problems caused by heat, the which can be used to record addi- solved salts, adversely affects the rate of chemical reaction is in- tions of neat oil, temperature, con- emulsion. Basically, the minerals creased and the formation of centration, pH, etc. is important. and salts can cause corrosion prob- insoluble metallic soaps is The log book is a handy reference, lems inthe equipment, and they can accelerated. providing a record of the operating react with the emulsifiers in the 6. pH - pH is a measure of the systems. fluid to produce hard water soaps acidity-alkalinity of a fluid .. pH is which adversely affect emulsion controlled by the content of the Testi;ng in the Plant stability and lubricity. polar additives, such as fatty acids. A reservoir supplying a gear cutting As detailed earlier, these polar ad- Several steps are required to insure 3. or grinding machine is hot and ditives 3Je responsible fora fluid's successful in-plant testing program. aerated, which causes the water to lubricity. If the pH falls because of 1. Obtain management commitment evaporate. As this occurs, dissolved exhaustion of polar additives, for a testing program. salts and minerals increase in con- lubricity will be diminished; 2. Select a person to coordinate centration, and, thus, evaporation whereas, if the pH rises too high, testing. This person will serve as an. accelerates the formation of hard the emulsion will become unstable. in-plant consultant and also pro- water soaps. To counteract this Since the fatty acids affect pfl, it is mote education of employees as to problem, one should consider the important to measure them and fluids. use of deionized water, boiler water maintain pH at recommended condensate or softened water to operation levels. H is best to main- 3. Identify problem areas and initiate make up water lost to evaporation, tain pH with regular additions of a program to evaluate lubricating neat oil. fluids. 4, Bacteria - In many systems, 4. Select vendors who are up to date relative to the OSHA Hazard Com- bacteria can become a problem 7. Concentration - Maintaining the munications Program. because bacteria degrade the emul- correct concentration of neat oil in sion by digesting the emulsifiers and the reservoir is important because S. Moni tor direct costs such as cost fats. This problem becomes more tool. life and product quality will per gallon, cost per pound and cost severe as the bacteria secrete acidic suffer if the Iubrici.tyof the of additions. wastes which adversely aff·ect the fluid is excessively diluted. Concen- 6. Monitor indir,ectcosts, such as pH of the system, Changes in pH tration can be monitored by the maintenance additives, cost of affect emulsion stability and lubri- Babcock Method or by a hand-held disposal and dumping frequency. ciIy. There are a number of refractometer. 7. Find out if oil-based compounds bactericides available 'to control. the 8. Filtration - A dean fluid is essen- can be reclaimed to avoid problems problem. tial. to maintaining the emulsion, with disposal. S. Temperature - The tsmperature of tool life and product quality. Gear 8. Monitor tool life by considering emulsions used to cut or grind gears manufacturing fluid compounds original cost and .reconditi.oning must be kept between 1000 and can be contaminated rapidly with 0 cost. 130 F. This is important for several things such as oxide, chips, tramp 9. Consider finished product. quality reasons. oil from lubricating or hydraulic versus raw material utiliz-ed. a. If the emulsion is too cold, it systems and even items such as may not be fluid enough to be food, rags and mi.ll dirt. If these 10. Monitor the condition of the fluid pumped to. the tool/work- contaminants are not removed and of the gear manufactunng piece interface, This could from the system,. the effective life of equipment relative to the fluid "starve" the tool and ad- the fluid is shortened and product being used. versely affect tool life and pro- quaHty and productivity tails. 11 .. Evaluate the test program and duct quality. To overcome the inherent problems report results to management. b. U the emulsion overheats, the associated with disposal and 12. Implement changes wher,ethe high temperature degr.ades the replacement of lubricants, it is im- evaluation justifies the need.

42 Gear Technology 13. Expand and maintain the testing microemulsions are formulated to have 3. HIXSON, D.R. "Countervailing Coolant program so as to be prepared Ior smaller micells than semi-synthetic emul- Forces," Manufacturing Engineering, Oc- unexpected problems. sions; hence, they have more dispersed tober, 1980. p. 96. 4. REDGARD, M.P. ·Cutting Fluid Emul- 14. Be receptive to change as new particles, The small micells aUow almost sions," 1l1dustrial Lubrication and all incident light. to be transmitted. The technology supercedes the old. Tribology, July/August, 1979. pp. small miceUs mean microemulsions are After the testing program has been 149-152. generally marie stable than soluble oils or established, it is important to have some S. KIPP, E.M. 'Tribology Notes," Industrial semi-synthetics, Microemulsions have a means of measuring the effectiveness 'of l.ubrication (;Ind Tr.ibology, number of other advantages including September/October, 1980. PI'. 168-171. a given fluid when it is used on gear hob- low tendency to foam, non-corrosive bing, gear shaping or hard gear finishing 6. JENTGEN, a.t, The Key Role of properties, high detergency and wet out, Lubrication. in Metal Defo.rmaJion Pro- operations. Several test techniques are reduced tendency to form insoluble ~. SME, Detroit, Ml. 1972. available that go beyond the simple tool soaps,easy rnixability and longer life .. 7, SCHEY, JOHN A. Tribol,ogy in life test. Synthetic hydrocarbons compounded Metalworking: Friction, Lubrication and "On~Une" Monitoring - Today's Wear. American Sodety of Metals, with suitable diester fluids are yielding state-of-the-art CNC controls allow "on- Metals Park, OH, 1983. new high-molecular-weight synthetic line" optimizing and monitoring of cut- 8. Federal Register, "CFR 1910:1200 Hazard fluids with superior viscosity index and tin~ conditions during machine opera- Communication," Vol. 48, No. 228, Fri- shear stability compared to convendal tion. The information C3_nbe conect~d on day, November .25, 1983. a. peripheral microcomputer and ana- polymer-based viscosity improvers in 9, FELLOWS CORP,"Generating and Checking Involute Gear Teeth," Gear lyzed relative to changes in.cutting fluids. hydrocarbon base stock. Synthetic hydrocarbons exhibitexcellent oxidation Technology, Ma.y/lune. 1986. pp, 38-48. At the same time, new electronic gear and hydrolitic stability and have a very 10. AINOURA, M., SAKURAGl. I.. checking equipment can be used to high HIm strength. These synthetics are YONEKURA, M., NAGANO K. "A monitor such things as changes in pitch, Research on High-Speed Hobbins with more resistant to breakdown under high involute and lead given changes, in cut- the Carbide Hob," Journal of Mechanical temperature, and they are now being ting fluids or grinding fluids. Design, June, 1977. pp. 1-10. blended intoa number of different gear Statistical Quality Control - With the n. MONCRIEFF. A.D. "Hard Gear cutting and grinding oils. Synthetic advent 'of statistical quality control, it is Finishing,' Proceedings of AGMA hydrocarbons will probably not come Manufacturing Symposium, April, 1985. now possible to monitor product qual- PI'. 1-23. ity relative to changes in the Huids used into more widespread use until their cost 12. MAHAR, R.."Progress in CBN Produc- on g:iven gear gearshaper or decreases. a hobber, tion Grinding." Proc. Super Abrasives hard gear .finishing machine. The qual- Conclusion '85. Chicago, IL, 1985. ity of the finished gear can vary 13. lANGE. J. "Gear Grinding Techniques This article has reviewed lubrication significantly based on the type of fluid for Parallel Axes Gears." Gear being tested within the equipment. theory, fluid formulation, testmg and Technology. March/April, 1985. pp. Transducers for Fame and Torgue process controls. Particular emphasis .34-48. Measurement - A muJti-component was placed on factors affecting fluid 14. BOOTHROYD, G. Fundamentals of transducer can be used for analysis of selection, classification and testing, to Metal Machining and Machine Tools. McGraw-Hill. grinding, This instrument provides a shed light on the chemical background measure of two Forces, the vertical force and maintenance of gear cutting and and the vertical torque. In a typical ap- grinding fluids. Rapid advances in gear Appendix A plication, this instrument would he manufacturing technology, combined with customer demands for improved mounted on the work table of the grinder Human Compatibility. Cutting fluids product quality at lower cost, are mak- and the test piece attached ina fixture on must be assessed not only from a ing it essential that manufacturers of the top of the instrument. The ratio of physical, chemical and metallurgical gears obtain maximum utilization from the vertical forc'f and the feed force is standpoint, but also from the point of every fluid used in a plant. Careful a't- essentially a measure of the grinding view of operator acceptability and tention to the techniques outlined in this fluid's effectiveness. - safety. Health and safety considerations article can improve Auid maintenance are discussed in Appendix A. through systematic checks. The attention After the physical, chemical and New Developments paid to lubrication should yield im- metallurgical studies have been com- Thereare several new developments in proved product quality, higher produc- pleted, it is important to assess the fluid's the field of lubricating fluids for tl'l? gear tivity and lower overall costs. manufacturing industry. acceptability from a operator's stand- Refer'ences: Microemulsions are generally clear IL~e point. The oil-based or water-based fluid 1. SPRINGBORN, R.K., etal. Cutting and synthetic solutions. Really an offshoot of of choice should not cause physiological Grinding RuidS: Selection and Applica- problems. It is important to recognize semi-synthetics, microemulsions 'contain tion. ASTME, Dearborn, M[ 1967, a small amount of mineral oil in addi- that no material is competely hazard- 2. SCHEY, T..A. Metal Deformation Pro- tion to the other components which are cesses: Friction and lubrication. Marcel (continued on page 48) soluble in water. The difference is that Dekker, lnc., New 'tork, NY, 1970.

July/August 198743 CUTTING FLUID SELECTION ... OSHA has adopted the reports of several customers of those items may request (continued from page 43) major research groups into the Standard. Material Safety Data Sheets from their The International Agency for Research suppliers, it is not a legal requirement for on Cancer (lARC) has determined that the supplier to provide one. Ultimately, free, but most fluids can be handled some base oils are carcinogenic. An oil many suppliers of articles are providing safely given adequate safeguards. product which contains more than 0.1 % Material Safety Data Sheets, but it really One cannot simply pay lip service to of such a base oil will be required by is not necessary. the acceptability of a given lubricating OSHA to have a statement On the The OSHA Hazard Communication fluid. Both labor and the general public Material Safety Data Sheet that it con- requirement is a good one. and manage- are now demanding that industry operate tains a carcinogenic component, and that ment should support the law to the fullest in a responsible manner that protects the component must be identified. The pro- extent possible ..There has to be a genuine health of workers, the general public and duct container must also be labeled with commitment to increasing the health and the environment. increasing public such information. The oils in question safety of both labor and management. pressure prompted by major chemical ac- are primarily napthenic oils that have not The compliance program must start from cidents in Bhopal. india, and several undergone severe hydrogenation or sol- a base of respect for every individual similar, but less serious, accidents that vent extraction. employed by a company. No company occurred in West Virginia, has prompted At the same time. OSHA also requires has ever gotten into financial difficulty the federal and state governments to that any product that contains a compo- or in trouble with OSHA because it enact a number of new laws aimed at nent having a polynuclear aromatic adhered to a strict set of ethical eliminating or reducing risk of exposure (PNA) content greater than 0.1 % to con- principles. to hazardous chemicals. tain a statement to that eHect on the One such law is the new federal stan- MSDS, as substances that contain .PNA Acknowledgement: Presented Qt the SME Gem Pro- dard on Hazard Communication (29 are considered carcinogenic. Again, the cesslllg Q1Id MIllluiuctwing Clinic. Novembi'r 11·13. SdLQu.mburg. IL. CFR 1910: 1200) thai was established by product container must be labeled with the Department of Labor, Occupational such information. Safety and Health Administration Chlorine in the form of chlorinated (OSHA). As of November 25, 1985, paraffin is a. widely used extreme pressure chemical manufacturers, importers and agent. Chlorinated paraffins have been distributors are required to: tested, and OSHA requires that two types of these materials must indicate the a. Label containers of hazardous presence of a carcinogen on both the materials and to provide Material drum label and the MSDS. Safety Data Sheets (MSDS) to The concern over the carcinogenic anyone purchasing these chemicals, nature of some base oils is justifiable b. Notify their employees of the haz- from a health standpoint, as well as from ardous materials in the workplace, the viewpoint of potential for adverse c. Demand appropriate training as to employee reaction and litigation. Users the safe handling and use of these of all types of lubricating Huids are ad- materials, vised to be familiar with the Standard d. Properly label all hazardous mate- and come into compliance. rials at the workplace, Most manufacturers of gears use a wide variety of lubricating fluids and e. Properly label all products shipped various chemicals. but do not actually from suppliers, manufacture or import them for sale to f. File Material Safety Data Sheets others. Therefore, the May 25, 1986, date (MSDS) that provide additional was the important cutoff for employers health and safety information on all in SIC Codes 20-39, in that their Hazard hazardous materials in the Communications training program had workplace, to be in place by that date. g. Post employee rights under the act, There is a good deal of confusion h. Be in compliance with all require- relating to the labeling of non-chemical ments of the Standard as of May products. The OSHA standard does not 2:5, 1986, as an employer in S[C require manufacturers of non-chemical Codes 20-39. products to label or to supply Material Safety Data Sheets to customers. The The new federal Standard on Hazard Standard provides complete exclusion for Communication has had a significant im- four categories of items including articles. pact on all compounds containing GeMS are an example of an article. While petroleum derived base stocks because

48 Gear Technology