Volume35 May, 1949 Number5£ul ricationA Technical Publication Devoted tothe Selection and Use of LubricantsTHIS ISSUEMachine Tool Lubricationon theProduction LinePUBLISHED BYTHE TEXAS COMPANYTEXACO PETROLEUM PRODUCTS
Stop rust and sludge in your hydraulic sys-tems by using Texaco Regal Oils (R & O)as the hydraulic mediums. You’ll assuresmooth, uninterrupted production andlower maintenancecosts.Texaco Regal Oils (R &O) keep hydrau-lic systems clean because they’re turbine-grade oils with special additives to inhibitrust and oxidation - and specially proc-essed to prevent foaming. Youcan get themin the correct viscosity for your equipment,whateverits type or size.., and they’ll giveyoulongerservice life than uninhibitedoils.Leading manufacturers of hydraulicequipment either recommendor approveTexaco Regal Oils (R &O) . . and manyship their units charged with them.Let a Texaco Lubrication Engineer helpyou get maximumefficiency and economyfrom your hydraulically operated machines.Just call the nearest of the morethan 2300Texaco Wholesale Distributing Plants inthe 48 States, or write TheTexas Company,135 East 42nd Street, NewYork 17, N. Y.
LUBRICATIONA TECHNICAL PUBLICATION DEVOTEDTO THE SELECTION AND USE OF LUBRICANTSPublishedbyThe Texas Company, 135 East 42nd Street, NewYork 17, N. Y.Copyright 1949by TheTexasCompanyVoLxxxv May, 1949 No.5Changeof Address:In reportingchangeof addresskindlygivebotholdandnewaddresses."Thecontents o[ ’LUBRICATION’are copyrightedandcannotbe reprintedby other publicationswithoutwrittenapprovalandthen only providedthe article is quotedexactly andcredit givento THETEXASCOMPANY."MachineTool Lubrication on theProduction Line"’~" F AUTOMOBILESwere madetoday with the ma-I machinetools of 1910, a single vehicle with1949 refinements, would cost $60,000"-thusestimated the AutomobileManufacturers Associa-tion recently. Whata tribute to the advancementsmadein machinetool designduringthe last forty years.Just as spectacular hasbeen the developmentof pe-troleum technology duringthis sameperiod. Modernre-fining methodsso necessaryto removeundesirable com-ponents of petroleumpr.od-ucts and the use of variousadditives to fortify or am-plify desirable propertiesaremajor advancements madeduring the last several dec-ades.Asis true withpracticallyall industries, advancementsmadein one usually comple-ment or makespossible ad-vancementsin another. Themachinetools of today would~clatter to a suddenstop ifthey were lubricated with manyof the productsavailable in 1910. Onthe other hand, petroleumrefineries could not be operatedat economicalcostswithout modernmachinetools to producethe tensof thousandsof parts so necessaryin their construc-tion and operation.Machinetools nowavailable are capableof turn-ASIMPLIFIEDLubrication Plan FotMachineTools:--the theme ofthis article, presentsa meansfor main-tainingqualitylubrication,yet reduc-ing costs of maintenanceandthe totalnumberof lubricants used in a givenproduction shop to a minimum.Theformulationof a simplifiedlu-brication plan mustof necessity in-cludea thoroughunderstandingof theoperatingcharacteristics of machinetools and an intimate knowledgeoflubricant recommendationsissued byindividualmachinetool builders. Sucha plan couldnot be effective withoutthe availability of recentlydevelopedlubricants, particularly of the addi-tive type. Theselubricantscanbe usedovera muchwiderrange of operatingconditionsthan waspossible withlu-bricantsavailable nottoo longago.ing out finished products at speeds and with anaccuracythat is astounding. Todo this, however,it is necessarythat all the parts of a givenmachinetool function properly. Onevery important factorcontributingto satisfactory performanceis effectivelubrication. Withoutthis, ac-curacy maybe lost, oils mayoverheat causing temporarymisalignment of machineparts, or metal to metal con-tact mayoccur causingrapidwearor completeseizure be-tweenmovingparts.Importanttoo is the lengthof time the lubricant "staysput" in the machine.Mostlu-bricants today-both greasesand oils - are manufacturedso as to withstandoxidationand other deteriorating fac-tors for muchlonger periodsthan waspossible only a fewyears ago.Another important factorin machinetool lubricationiseconomy.Howcan the besteconomyin lubrication andmaintenanceof machinetools be obtained?- Byin-telligent lubrication, namely1. Theuse of the right product for each require-ment.2. Byapplyingquality lubricants designedto pre-vent wear and the formation of gum,sludge,49]
LUBRICATION May, 1949Figure ! - Automaticlubrication systemfor oiling this five spindle automaticbar machinemanufacturedbyThe Warner & Swasey Company.rust or foam,any of which,if permittedto de-velop, can causeexcessivemaintenancebills.Bymakinguse of a simplified lubrication planto reduce inventories and minimizethe possi-bility of costlyerrors dueto a mix-upin productsused.It is the purposeof this article to presenta sim-plified lubrication plan for relatively large groupsof machinetools, to explain recent developmentsin such tools whichaffect lubrication and to showhoweconomiesmaybe effected by the use of mod-ern, quality-typelubricants available today.IMPORTANCE OF EFFECTIVELUBRICATIONEffective lubrication of machinetools meansmuchmorethan the use of the correct grade oflubricant at the right place in sufficient quantityto adeqt, ately lubricate movingsurfaces. It includesalso the use of products whichwill function overlong periods of time without appreciable changesin theirphysical or chemicalcharacteristics, theuse of efficient filters wherenecessaryto keepoutcontaminants, the application of the minimumamountof lubricant necessary to prevent wastage,and other similar factors. Onlywhenall such con-ditions are taken into considerationcanlubricationbe assuredwhichwill result in continuoustrouble-free operationover long periods of time a~ a mini-i~lum cost.Thepresent era has focussed muchmoreatten-tion on lubrication than ever before. Primarily,this is dueto twofactors:(a) Therising cost of maintenancewhich fa-vors automatic and positive meansof re-lubrication.(b) The development of precision machinescapableof muchhigher rates of production.Thelatter, particularly, has beenresponsibleforincreased attention being given to morecarefulselectionof lubricants.It is unnecessaryfor machinetool operators todeterminethe grade of productto be used for eachbearingor gear in all the machinetools he operates.Thisresponsibility, andrightfully so, lies withthemachinetool manufacturerand lubricant supplier.In years gone by, manymachinetool manufacturersmadeno lubricant recommendationsat all, or atleast, onlyvery meagerones. Eventhoughthis con-dition still exists today with somemanufacturers,the majority issue lubrication instructions givingexplicit advice as to proper lubrication of theirmachines.Suchinstructions are prepared as a re-sult of tests madeby the manufacturer,usually incooperation with lubrication engineers from oneor moreproducers of petroleumproducts.Regardless of the diversity of such manufac-turers’ recommendations,in any production plantcontaining numerousmachinetools it is necessary[ 50]
LUBRICATIONand economical to reduce the total numberoflubricants used to an absolute minimum.Manyplants employa lubrication engineer, and if so,this is his responsibility. In the majorityof produc-tion shops, however,no employedlubrication engi-neer is available andin such cases consolidationissponsoredby the oil supplier.Oneof the factors which has madepossible theconsolidated or simplified plan presented herewithis the tremendousadvancementmadein the qualityof petroleumproducts during the last decade. Asa result of improvementsmadein greases, for ex-ample, only one grease is normally employednowto meetall grease requirementsin a specific pro-duction shop. For this reason, as a required pre-requisite to anysimplifiedplan, it is necessarythatthe types of products available today be clearlyknown.Quality of LubricantsModernmachinetools equipped with anti-fric-tion bearings and precision gears operating withclose tolerances and at high speeds, are in themajority of cases equippedwith splash, bath, orcentralized lubricating systems. Suchsystemsre-quire the use of the highest quality lubricants.Experience has shownthat the use of "quality"products reduces maintenancecosts, and improvesmachineperformance.Oils usedin reservoirs shouldbe so refined thatthey are highly resistant to oxidation- otherwisegumor sludge maybe formed, resulting in un-necessary downtime to clean out the machine.Inaddition it is highlydesirable that their propertiesbe further fortified by the incorporation of addi-tives. Dependingupon the type of oils used andthe properties needed, various present day oilscontain additives to improveoxidation resistance,to prevent rust formation, to overcomefoamingdue to entrained air and to increase extremepres-sure, oiliness, or adhesivequalities.Theacceptanceof the use of additives in petro-leumlubricants is shownby the fact that in thelast fifteen years the additive manufacturingin-dustry has grownuntil nowapproximately 1,500barrels of additives are producedper day with anannualvalue of $35,000,000.00.Themanybenefitsto be derivedby the use of additives in lubricantswill be discussed in detail under various ensuingsections.Cheaperor secondgrade oils are still used onsomemachinetools, particularly machineswhichare rather old. Suchoils are satisfactory for "oncethrough" lubrication points such as oil cups, oilholes, wick feed and similar oiling methodswhereCourtesy oJ Alemit¢ Division, Stewart-Warner CorporationHgure2 -- Portion of a grease dispensingsystemon a Bullard vertical turret lathe.
LUBRICATION May, 1949the oil makesa single pass through the bearing.Evenwith older machines predominantly lubri-cated byoil cups, however,it is often desirable touse quality lubricants. Suchmachinesare usuallyin a minority in any given shop and stocking oftwooils of the sameviscosity, onea high gradeforreservoirs and the other a cheaper grade for oilcups, proves moreexpensivein the long run.ViscosityTheimportanceof using the correct viscosity orgradeof oil cannotbe overstressed in the lubrica-tion of modernprecision machinetools. In oldermachines, or in tools whichdo not produce workto close tolerances, viscosity is less importantandoils with a rather widerange of viscosities maybeusedwithentire satisfaction.Onclose fitting parts used so prevalently inmoderntools the viscosity should be kept withinthe limits specified by the manufacturer.Obviously,it shouldnot be so lowthat metal to metalcontactmight occur. Theuse of an oil having too high aviscosity also has several disadvantages. Internalfriction developedin the oil can causeit to over-heat, resulting in morerapid oil deterioration andheating up of the metal parts surroundingthe oil.Thelatter is particularly troublesomeon machinesworkingto very close tolerances for the excessiveheat generated maybe sufficient to expand theframe of the machine,or parts thereof to such anextent that the cutting tools or workmustbe resetperiodically.Courttsy o[ Th¢ Farral CorporationFigure3 -- Centralizedoiling systemon a Mitts & Merrill No..SKey Seater.Courtesyof Man:elInc.Figure 4 -- A four feed automaticlubricator usedto lubricatethe waysof this knife grinder manufacturedby SamuelC.Rogers& Co.SIMPLIFIED LUBRICATION PLANSimplification and economyare intimately re-lated in so far as the lubrication of machinetoolsis concerned.Progressivemachinetool operators are constant-ly endeavoringto reducethe total numberof lubri-cants required for the proper lubrication of theirmachines.This has beeninfluenced in recent yearsby several factors, includingthe increasing cost ofmaintenance, the necessity of reducing overheadexpensesand primarily, the availability of newertypes of lubricants whichare capableof function-ing underwidevarieties of conditions.Theprimarypurposeof this article is to presenta simplified lubrication plan for machinetools.This plan takes into account all of the abovefac-tors. Briefly, it presents a methodfor consolidatingthe numberof lubricants used in a given produc-tion shopto an absolute minimum.Specifically, theproducts recommendedin this plan are showninTableI.Thisconsolidatedor simplifiedlist of lubricantsfor large production shops, was developed as aresult of a studyof all machinetool manufacturers’lubricant recommendationsand extensive field ex-perienceobtained with the types of products recom.mended.This list will apply to the great majorityof machinetools in use today. (In a fewinstances,however, specialty products maybe required.)Evenall the products listed maynot be necessaryin a given production shop; for example, the useof two greases, twohydraulic oils or several waylubricants and spindle oils maybe unnecessary.In order that the recommendations mademaybe understood moreclearly each is discussed indetail in the followingsections.
LUBRICATION~ ~ ~ oo oo ~ ~Z Z[~]
LUBRICATION May, 1949Figure5 -- Schematicp/an of hydraulicandlubricatingHydraulic SystemsProbably nowhereon a machinetool can troubleoccuras often as in the hydraulicsystemif acceptedmaintenance procedures are not followed. Theseinclude the use of the correct grade of oil with aquality commensurateto demandsplaced on theoil by the hydraulicsystem.Manyfactors contribute to the need of specialcare in selecting hydraulic oils. Conditionswhichcause oils to oxidize present one of the foremost.Theseconditions include operating temperaturesranging up to 150° F. or even higher in a fewinstances, severe agitation at each pass throughpumpsand valves, pressure, the presenceof metal-lic catalysts and unfortunately in someinstancesvarious contaminants such as cutting oils. As aresult, inhibitors are nowincorporatedin hydraulicoils to retard oxidation; their effectiveness beingphenomenal.Field experience has shownthat in-tervals between drain periods maybe increasedmanytimes over that obtainedwith straight mineraloils, and moreimportant the possibility of gumorsludge formation in the systemis almost entirelyeliminated.Rust formation in hydraulic systemsis anotherfactor contributing to poor hydraulic systemper-formance. Rust can be caused by condensation ofmoisture in the reservoir, contamination such asfromcoolants, or leaking water coolers. Fortunate-ly, rust formationcan be preventedby the additionof small amountsof inhibitors to the oil. TheseCourtesy o] Norton Companysystemof a 6" Type CCylindrical GrindingMachine.inhibitors "plate out" on metal surfaces, forminga film whichis imperviousto the rusting action ofmoistureand air.A third factor is foaming,whichis troublesomein somesystems. Hereagain, it is possible to sotreat or processthe oil that anyentrainedair in theoil is quickly separated. Thepresence of air inhydraulicoils can result in erratic motionof actu-ated parts, cancausethe oil to oxidizemorerapidlyand if foamis formedin the reservoir the probableoverflowis unsightly and a safety hazard.During the last several years the economyofusinghigh quality inhibited type hydraulicoils hasbeen proven time and time again. Little wonderthey are used almost exclusively today in machinetool hydraulicsystems.Mentionhas previously beenmadethat viscosityis an important consideration in the selection ofoils. Since pumpsare the most critical part of ahydraulic systemin so far as lubrication is con-cerned, pumpmanufacturers have madeextensivetests to determinewhatviscosity oil performsbestin systemscontaining their pumps.It is necessarythat the viscosity be sufficiently high to preventmetal to metal contact and to give high volumetricefficiencies, yet it must be low enoughto pumpeasily so that pressure drop throughthe systemisat a minimum.For these reasons pumpmanufac-turers issue specifications indicating the correctviscosity to be used under various operating con-ditions.[ 54]
LUBRICATIONFortunately, practically all hydraulicpumpsusedon machinetools require the use of two grades orviscosities of oil, one being 150and the other ap-proximately 300secondsat 100° F. Say. Univ. Forthis reason, two grades of hydraulic oil are shownin Table I, but perhaps only one maybe necessaryin a given productionshop.General Machine LubricantRelegated to history is the general use of oilholes, oil cups or other manualmeansof applyingoil to modernproduction machinetools. In theplace of such devices centralized pressure, splashor similar formsof lubrication are nowalmostuni-versally accepted. Thegreat majorityof productionmachinesbuilt todayare so lubricated that little orno attention is required at time intervals rangingfrom a minimumof once a shift to long periods oftime. Evenmachineslubricated once each shift arefor the most part equipped with so called "oneshot" systemswhereit is necessarymerelyto pullout a knobto relubricate the machine.Centralized systems range from "one shot" tocompletelyautomatic systemsin whichit is merelynecessary to periodically replenish the reservoirwith oil. Applications of such systemsto machinetools are shownin the illustrations accompanyingthis article.Eventhoughautomatic lubrication is a featureof almost all production machines, remote spotswhichcannototherwise be lubricated economically,mayrequire application of oil by sight feed oilersor oil cu~s. These must not be overlooked whenrelubricat~ng.Just as the use of automaticlubricating systemshas becomeso commonduring the last few years,so has the use of inhibited lubricating oils forgeneral machinelubrication. In fact someopera-tors havefoundthat using inhibited hydraulic oilsfor general machine lubrication has saved themmoneyin maintenance and downtime costs. Onereason is that rusting is a detrimental factor inhumidatmospheresand of course this can be over-comeby the use of rust inhibited oils. Thepos-sibility of gumor sludge formationas the result ofoil oxidation, and foaming caused by air beingbeaten into the oil are other detrimental factorswhichcan be overcomeby using inhibited oils in-stead of straight mineraloils.Afourth type of additive currently comingintospecialized usage imparts extreme pressure char-acteristics. Oils containing suchadditives are nowCourtesyof TraborEngineeringCorporationFigure6- Centralizedgreaselubricating systemon a turret lathe. Notepumpandreservoirlocatedinlower right handcornerandmountedin a horizontalposition.
LUBRICATION May, 1949Courtes7of Bijur Lubricating Corp.Figure 7--Automatic oiling systemfor a thread generatormadeby The Fellows Gear Shaper Company.Gears Other Than Those Lubricated bythe General Machine LubricantSomemachine tools are equipped with gearswhich require a muchhigher viscosity productthan that used as a general machinelubricant.Typical ex~mpIesare found on someback gears ofvertical or larger type horizontal turret lathes,columnmechanisms’of milling machines, screwmechanismson boring mills, etc. Such productsusually fall within the SAE-90or 140 viscositygrade, and the specific viscosity andtype of prod-uct required is normallyspecified by the machinebuilder.Gear lubricants in so far as type is concerned,fall withintwoclassifications, straight mineraloiland extremepressure lubricants. Straight mineraloil type gear lubricants shouldbe well refined andhighly resistant to oxidation. In addition, theyshould be so processed that they do not foamwhenmixed with air, or emulsify whencontaminatedwith water.Withr.espect to extremepressuregear lubricants,the lead soap base type has beenoutstanding. This~PmeiS non-corrosiveto copperor steel, has a highstrength, is unaffectedby presenceof moistureand does not thicken or oxidize appreciably inservice. Leadsoapbase extremepressure lubricantsspecified by several manufacturerswhosetools con-tain heavily loaded bearings. Typicaltypes of ma-chine tools include somegrinders for crush dress-ing, centerless thread grinders, and vertical turretlathes.Thegreat majority of machinetools require theuse of a general machinelubricant having a vis-cosity of approximately 300 or 500 seconds Say.Univ. at 100° F. However,certain tools, mayre-quire an oil havinga viscosity of only 200secondsat 100° F. In general the lowerthe viscosity, theless will be the heat generatedby internal frictionin the oil. Lowviscosity oils are used wheredis-tortion of machineparts, caused by oil heating,must be minimized.Basedon present indications there are certaindefinite trends in general machinelubrication, i.e.(1) the ever increasing use of automaticlubri-cating systems(2) general acceptance of machinelubricantscontaining inhibitors to prevent oil oxida-tion, rust and foaming(3) an increase in the use of extremepressureagents in oils for use on certain types ofmachines(4) a general lowering in the viscosity of theoil used as machinestolerances are de-creased.Courtesy of The Farval CorporationFigure 8 - A centralized oiling systemon a special horizontaldrumtype Barnesdrill.
LUBRICATIONare recommendedfor use on all types of gears,including wormgears, for use on anti-frictionbearings containedin the gear case, on screws, andsimilar applications. For these reasons, this typeis often used whereboth straight mineral and ex-treme pressure gear lubricants are specified byvarious manufacturersfor their tools in a specificproduction shop in order to simplify the numberof products used.Sulfur-chlorine, "mild"type extremepressure lu-bricants canalso be used on gears but beforedoingso it shouldbe ascertainedif they are corrosive, orwill stain steel or copper.Gearlubricants are normallycontainedin reser-voirs, the gears being lubricated by splash or by aforced feed system. A few specialized machinescontain what are termedopen gears, that is, theyare not contained in an oil tight housing. In suchcases, it is necessary that an adhesive type gearlubricant be applied directly to the gears. Suchproducts are madefrom heavyresidual stocks andare su~cientlyadhesiveand cohesivethat they willnot throwoff.SpindlesHigh speed spindles on grinders and similartypes of tools require extremecare in the selectionCourtesy ol Sundstrand Machine Tool Co.Figure 10--Automatic lubrication for gear train and spindlein a No. 33 Rigldmill. The oll pumpactuated by an eccentriconthe lower shaft delivers oil to the headerfromwhichi~ isdelivered to individual bearingsby tubing as indicated. Notethe flow gagethroughwhichvlsual observationwill showthatthe distribution systemis functioningproperly.Courtesyof Kearney& Trecker Corp.Figure9 -- Illustrating howonemilling machineis lubricatedby force feed from three reservoirs. In eachcase the oil iscirculated to points of application by small pumps.of the proper lubricant. Spindles maybe eithergrease or oil lubricated dependinguponthe design.Withrespect to oil lubricated spindles, speedand load on the bearings are two primary con-siderations in the selection of a proper lubricant.Otherfactors, however,suchas the type of bearinginvolved, possibility of contaminants (grindingdust for example) entering the bearing housingand methodof lubricant application also play animportantpart in the choiceof a lubricant.It is absolutely essential that there be no playin spindles, therefore, clearances are held to aminimum.Also, there has been a definite trendtoward higher spindle speeds. As clearances aredecreased and speeds increased, it is normallynecessary that the viscosity of the lubricant belowered. It is for this reason that somemanufac-turers specify very lowviscosity oils for spindles.Thereasons for using lowviscosity products onmodernhigh speedspindle bearings is simply thatif high viscosity products wereused, the bearingsmight overheat and ultimately seize, the hot oilwouldoxidize morerapidly and the hot metal sur-roundingthe oil wouldexpand,thus affecting theaccuracyof the machine.Spindle bearings range in design all the wayfrom sleeve type bearings to three part bearings(half boxlocated at the bottomand to the rear of[~]
LUBRICATION May, 1949the spindle housing with two adjustable bearingsegmentson top), three or five pivoted shoe typesand, of course, anti-friction bearings.Methodsof oil lubrication range from the useof sight feed oil cups, spring-actuated wickoilersand ring oilers to flood lubrication andmist appli-cation.*Oil lubricated spindles require products rangingin viscosity from 40 to 300 seconds at 100° F.,Say. Univ.dependinguponfactors discussed above.Although general recommendationscan be made,as indicated below,it is best to follow the manu-facturers’ recommendationsas to the correct vis-cosity of oil to use in a specific spindle. In generalsight feed oilers, wickoilers, and ring oilers areto be found on comparativelylow speed spindles,whereasflood and mist type lubrication are usedon higher speedbearings, with mist being used atvery high speeds. Therefore, based on methodofoil application the following very broad recom-mendations can be made:GeneralViscosityRangeof Oil, Say.Methodof Oil Univ.SecondsatApplication 100° F.Sight feed oilers 100- 2OOSpring-actuated wick feed 100- 200Ring oiled 200 - 300Floodor circulating 40- 300Oil Mist 50- 150In systemswherethe oil is circulated to the bear-ings and backto a reservoir (ring oiled, splash,flood or force feed) it is essential that the productused be of goodquality. Theoil mustbe resistantto oxidation, not emulsify with any water of con-densation or contamination,and quickly free itselfof any entrained contaminants, such as grindingdust. In both circulating systems and with mistlubrication, whenapplied to anti-friction bearings,it has been found that rust is sometimesa factorwhich can cause serious bearing damage.In orderto overcomethis, rust inhibited oils have beenresorted to withcompletesuccess.Sofar, this discussion has concernedoil lubri-cated spindles only. However,where there is apossibility of oil leakage,or underconditionswheredirt, dust and other contaminantscan get into thebearing, greaseis often used. In such cases, a pre-miumgrade anti-friction bearing grease of a No.2NLGIconsistency, such as described in the sectionto follow on "Greases", should be used.Nodiscussion on spindle lubrication wouldbecomplete without a word on cleanliness. High*Spindle design and methodsof oil application ha~,e been .dis-cussed in more detail in two previous issues of MagaztneLubrica-tion; July 1948--"Metals Grmding Machinery Lubrication", andSeptembe~ 1948--"High Speed Ball Bearing Lub~icafioa".Courtesy of Cincinnati Milling andGrinding Machines, Inc.Figure 11 -- Lubricatinglines in the saddleof a No. 2 CutterandTool Grinder, with table removed.Oil is fed to the dis-tributor in the center fromwhichit goesto various bearings.speed spindle bearings can be ruined by smallparticles of dirt. Forthis reason,air usedin mistlubrication should be filtered to removeentraineddirt and moisture. Everyeffort should be made,also, to keepcontaminantsout of circulating oilsand if the oil does becomecontaminated,it shouldbe changedimmediately.WaysNomatter howwell a machinetool is designed,if the waysare not properly lubricated accuratemachiningcannot be accomplished. Off hand, onewouldthink it simple to lubricate two flat or Vshaped surfaces uponwhicha carriage, turret orworkrest must ride. Quite to the contrary, how-ever, this is one of the critical points in machinetool lubrication and a great deal of research hasbeen conducted by both machinebuilders and oilsuppliers on this problem.As a result of someofthis work,new"special" waylubricants havebeendevelopedrecently and are receiving ever increas-ing acceptance.One of the primary problems encountered onmanymachinewayswas chattering, which causedirregularities in the workbeing done. Since chat-tering normallyoccurs just after motionhas beenreversed, the most commontheory wasthat on theforward motion oil was wiped off the way, thenas motionwasreversed the carriage had to traversea comparatively dry waybefore the oil supplycould be replenished. Another problem was thatif the carriage was stopped the lubricant had atendency to press out with the result that whenthe carriage was again movedit occurred in a"stick-slip" motion. Chattering predominates onsomemilling, shaping, grinding and similar typemachineswherethe carriage goes back and forth
LUBRICATIONat predeterminedcycles. "Stick-slip" motionis ofprimaryconcernon such equipmentas lathes wheretools at timesare advancedinto the worka fractionof an inch.In addition to overcomingthe aboveproblems,a waylubricant must have other properties. Toenumeratethe moredesirable qualities:1. It shouldeliminatechatter.2. It shouldnot press out uponstanding.3. It should contain oiliness and extremepres-sure agents to prevent metal to metal contactbetweenlocalized high spots.4. Theoil film thickness built up shouldnot besufficiently thick to affect the accuracyof theworkbeing done.5. It is essential that it be non-corrosiveto steelor the copper found in the oil distributionsystem.6. It should not plug felt filters found in somecentralizedsystems.7. It shouldnot washoff or be adverselyaffectedbycutting fluids, coolants or water.Waylubricants having all the abovedesirablequalities have been developed and placed on themarketin the last several years. Wherechatteringor "stick-slip’" troubles havebeenencounteredwithstraight mineral oils, oils compoundedwith fattymaterial or even lead soap base gear lubricants,these troubles havebeen eliminated by the use of"special" waylubricants.A variety of type of lubricants maybe used onways, dependingboth on the load and methodoflubrication. Whereloads do not exceed approxi-mately 10 poundsper square inch, a straight min-eral oil havinga viscosity of about300secondsat100° F. Say. Univ.is used, unless the machineman-ufacturer specifies a somewhatheavier grade.Whenloads are above10 lbs. per sq. in. it isusually necessary to use a high viscosity straightmineraloil, or moreoften, a fortified mineraloil.In the past compoundedoils, containing fatty ma-terial whichincreases "oiliness", andvarious typesof extremepressure gear lubricants havebeenused,with success rangingfrom goodto only fair. It isconfidently believed, however, that the machinetool industry will standardizeon the use of specialwaylubricants such as the type described at thebeginning of this section whensomething morethan a straight mineraloil is required.Cross slide waysand comparatively short waysmaybe lubricated through oil cups, or by similarmetho.ds, but longer waysare almost universallylubricated through "one shot" or other forms ofa centralized distribution system. Mostare auto-matic so that on each stroke the waysreceive ashotof oil.Wayson somemachinesare lubricated from thehydraulic systemor headstock. In such instances,small diameter coppertubing conductsthe oil fromthe hydraulic circuit or headstockto the ways.Itis necessarythat the lubricant serve the dual pur-pose of hydraulic or headstockand waylubricatingoil. At the present time only somelight duty ma-chines are designedin this mannerand the choiceof a suitable lubricant requires specialized atten-tion. In a few instances waysare lubricated byexcess cutting fluid splashing on the ways.GreasesModernmachine tools are predominantly oillubricated, however, grease is used on electricmotors, coolant pumps,on somespindle bearingsand on miscellaneous applications such as togglemechanisms,sliding surfaces (other than ways)and someinaccessible bearings.WHEELHEAD WAYSK----FLAT’11.I |....mm .. -- .m mJrm~¯ TABLEt VEE"WAYS[irlt.FLATCourtesy ol Cincinnati Milling and Grinding Machines, Inc.Figure 12 -- Diagramof lubrication systemon waysof a 4" Plain Hydraulic Grinder.
LUBRICATION May, 1949Experiencehas shownit is generally desirableto stock only onegrease for all greaseapplicationsand in such instances, the type of grease used isdictated by the requirements o~ high speed greaselubricated spindles or electric motors. In theseapplications a premiumgrade No. 2 NLGIgreasecontaining a sodium-calcium mixedbase soap, amineral oil with a viscosity of 150to 400secondsat 100° F. Say. Univ. and an inhibitor to retardoxidation is used. Sucha product has provenen-tirely satisfactory on highspeedanti-friction bear-ings such as foundon spindles and electric motorsand at continuous operating temperatures up toat~out 250° F. In a fewcases, onparticularly largeor heavyduty equipmenta sodiumsoap base greasecontaininga highviscosity oil is required, for sucha product will withstand heavier loads than willthe type recommendedfor electric motors andspindles.Onmanyolder machines, plain bearings wereused extensively and for these an ordinary cupgrease wasused. Eventhough manyof these ma-chines are still in operation, most operators nowuse the type of grease required for anti-frictionbearings (described above)for such points. Itoften found moreeconomical to carry only onegrease for all grease lubricated points rather thantwo greases, one for anti-friction bearings and acup grease for plain bearings. Someoperators havegoneso far as to say that the merepossibility ofexchangingthese twotypes, resulting in the almostcertain failure of high speedanti-friction bearingsis sufficient reason to preclude the stocking of acup type greasefor plain bearings.The application of grease on modernmachinetools has beengreatly simplified. In the past it wasnecessaryto completelycircle the machineto reachall points. Themoderntrend is definitely towardthe use of a centralized distribution system(seeaccompanyingillustrations) or, at least to supplya centralized panel ecjuippedwith pressure greasefittings and connectedto various bearingsby suit-able tubing, thus makingit almost impossible tomissan isolated bearing.Dual or Tri-Purpose OilsNosimplified lubrication plan for machinetoolswould be complete without consideration of aspecial problemwhich arose in the case of somemultiple spindle bar and chuck type automaticscrew machines.This problemrelated to the main-tenanceof the correct cutting oil in these machinesfor it wasfound in someinstances the machine’slubricant, and sometimesthe hydraulic oil, werediluting the cutting oil in sufficient volumeto re-ducethe active ingredients in the cutting oil. In afew instances, the direction of the dilution wasreversed; in these cases, the cutting oil being theoffender by contaminating the lubricating and/orhydraulic oil, thus resulting in sludge formation,corrosion and ultimately ruined machineparts.Toovercomethis situation "DualPurposeOils"were developed which could be used as a generalmachinelubricant as well as the cutting fluid onbar type automatics. Subsequently, their use wasextended to the hydraulic system on chuck typeautomatics,resulting in their accepteddassificationas "Tri-PurposeOils".Dual or Tri-Purpose Oils are non-corrosive tosteel or copper. Years of experience has shownthemto function efficiently as a machinelubricantanda hydraulicfluid in these systems.In addition,they give excellent tool performanceon all ma-chining operations which are considered mild orslightly on the tough side. Evenon "tough" jobsthe effect of dilution fromthat portion usedin thelubricating systemwill be far less than if straightmineraloil had beenused in the latter.Warning:-It is absolutely essential that onlyfresh clean oil be addedon the lubricating side ofthe machine.Oil fromthe cutting oil sumpshouldnever be addedto the lubricating oil reservoir forif it is, the chips in the latter wouldsooncauseserious damageto the bearings.CONCLUSIONMachinetool manufacturers are to be compli-mented on the ever increasing attention beinggiven to lubrication. Manymanufacturershave de-voted a great deal of time and effort in order todetermine the most satisfactory grades of lubri-cants to be used; they are very consciousof theirresponsibility to their customersin passing thisinformation on to them.Machinetool manufacturers also are designingmoderntools so that a minimumof attention canbe given re-lubrication. Methodsused include thealmost universal acceptance of centralized lubri-cating systemwith their manyadvantagesof posi-tive lubrication and savings in labor and mainte-nancecosts.ThePetroleum Industry, too, is proud of thelubricants developed in recent years which makeit possible to use a single product over an everbroadeningrange of conditions. Modernlubricantsalso function over muchlonger periods of time.Suchlubricants permit the developmentof a sim-plified lubrication planas describedin this article.Printed in U. $. A. bySalle~_&Collins, Inc.30.~ East 45th StreetN~w York 17. N. Y.
TEXACO LUBRICANTSFOR MACHINE TOOLSParts to be LubricatedHYDRAULIC SYSTEMLow Viscosity ................................................MediumViscosity .............................................GENERAL MACHINE LUBRICANTLow Viscosity ................................................MediumViscosity .............................................High Viscosity ................................................GEARS(Not lubricated by general machine oil)Lightly Loaded- Other Than Worm............................Heavily Loaded- Other Than Worm...........................All WormGears ..............................................SPINDLESOil LubricatedBy Oilers and Wick Feed ...................................By Ring Oiler ....................... ~ ......................By Circulating or Flood System ............................By Oil Mist ................................................Grease Lubricated ............................................WAYSLightly LoadedMediumViscosity ..........................................High Viscosity .............................................Heavily Loaded or Where Chattering OccursMediumViscosity ..........................................High Viscosity ............................................GENERAL GREASE LUBRICATIONNormal Operation ............................................TexacoRecommendationsTexaco Regal Oil A (R&O)Texaco Regal Oil PC (R&O)Texaco Regal Oil B (R&O)Texaco Regal Oil PC (R&O)Texaco Regal Oil PE (R&O)Texaco Thuban 90 or 140Texaco MeropaLubricants--3 or 6Texaco MeropaLubricants--3 or 6Texaco Regal Oils (R&O)Texaco Regal Oils (R&O)Texaco Spindura or Regal Oils (R&O)Texaco Spindura or Regal Oils (R&O)Texaco Regal Starfak No. 2Texaco Regal Oil PC (R&O)or PE (R&O)Texaco Ursa OilTexaco WayLubricantTexaco WayLubricantTexaco Regal Starfak No. 2Heavy Duty Operation ........................................ t Texaco Marfak No. 1, or MarfakNo. 2 Heavy DutyDUALANDTRI PURPOSE OILS FOR MULTIPLESPINDLE AUTOMATICSCREW MACHINESDual Purpose -- Machine Lubricant and Cutting Fluid ............. Texaco Cleartex Cutting Oil BTri Purpose -- Hydraulic Fluid, MachineLubricant and Cutting Fluid Texaco Cleartex Cutting Oil DDThe foregoing products are of highest quality and are recommendedfor use where automatic or circulatingsystem primarily prevail, as they do on most modern machines.Texaco Lubrication Engineers are thoroughly familiar with the Simplified Lubrication Plan for MachineTools. Let them help you simplify the numberof lubricants used in your production shops.
CutYoumetal curtUse TexacoCutting Coolants For FasterMachining, Finer Finish, FewerRejectsDrilling, grinding, milling, turning --whatever the metal or machining method-- there is a top-quality TexacoCutting,Gri~dbtg or Soluble Oil to help you doevery metal cutting job in your plant faster,better, and at minimumcost.Texaco Cutting, Grinding attd SolubleOils lubricate effectively. Theykeep tooland workcool -- prevent chip welding orwheel loading. They prolong tool life,assure cleaner cuts and smootherfinish, in-crease production and lower costs whereverthey are used.A Texaco Lubrication Engineer whospe-cializes in cutting coolants will gladly helpyou select-and use effectively--the Texacocutting coolants you need for best results.Just call the nearest of the more than2300Texaco Wholesale Distributing Plantsin the 48 States, or write TheTexas Com-pany, 135 East 42nd Street, NewYork17,New York.THE TEXAS COMPANYATLANTA,GA... 864 W. Peachtree StreetBOSTON17, MASS..20 ’Providence StreetBUFFALO3, N.Y. . 14Lafayette SquareBUTTE, MONT.. 2"20North’ AlaskaStreetCHICAGO4, ILL.. 332 So. Michigan AvenueDALLASI, TEX. . . 311 South Akard StreetDENVER1, COLO.... ~ ~ ~ 910 !6th Streetsr~rrLe,1 t, wA.sx.¯ TEXACOPRODUCTS * DIVISION OFFICESHOUSTON1, TEX... 7’20 SanJacinto StreetINDIANAPOLIS1, IND., 3521E. MichiganStreetLOSANGELES15, CAL. . 929 South BroadwayMINNEAPOLIS2, MINN. . 300 Baker Bldg.NEWORLEANS6, LA., 919 St. Charles StreetNEWYORK17," N.Y.. 205 East 42nd StreetNORFOLK1, VA. . Olney Rd. & Oranby St.::,.. 1~!1 Third AvenueTexacoProducl~ dbldlmted throug ,kaut.Canadaby M~oll-Front~nacOil Company,Umlted, MONTREAL,CANADA