Involute Spline Size Inspection - Gear Technology

1 InvoluteSpline SizeInspectionAbstractThis article describes anew technique Iorthe' size determinationof external Involutesplin,byusing provides application performance informa-tion demonstratinghowthismethod and itsmeasurements correlate with the 'traditionalsplin ring gage s~zing splines provide a positiverotational couplingbetweenashaft withexternalteethand relatedmatingmember with internal Spline teeth. Theiruse permitsease of assemblyordisassembly Ier replacement or servicing,and permits fixed or sliding uses permit compact assembly ofparts, or by use of standardized fittings,the intereouplingof motors with gearboxes or other there is nol10llingaction betweenthe mating members.

2 As there is betweenmeshing gears. aU of the Spline teeth areexpectedIto fit internal andexter:nalfits areavailable,the final goal of involutesplinesistoachieve a self centering con-dition with full contact bearing. Theresult oJ this would be equalized loadsharing and stress on all the manufacturing induced errorsdiminishlhisidea] equalized condition upto the point where a Spline may fail toproperlyengage its mating typical factors which affect propermating are: tooth thickness , space errors. profile and out of roundness. Amongthe manufacturingprocesses the onemost difficult to deal with is particularly troublesomeifthe part is slender.

3 'thinwalled or distortionbecomes extremelylikely and also probably screen out parts which witl1 notmate properly or not mate at all, it isnecessary to inspect the product pri'or tothe assembly operation. A very commonbyWilliam L [anninck& lUitronIllinois Tool Works of doing this is by the use of solidtool steel gages. For external splines. thegages are internal toothed rings called"GO" and 'NO GOr.(See Fig. 1).The "GO" ring is a composite gagehaving a full complement of teeth and isused to inspect maximum material con-ditions. minimizing the chance of fit in-terference. In other words,ifthe part fitsthe "GO" gage .]

4 There is a high probabilityof assembling with its mate later. The"GO" gage cannot measure the loosenesser size of'the part being reject those parts that will not enterthe "GO" The "NO GO" gage does not have afull compliment of teeth. but rather onlytwo diametricallyopposed groups used to inspect minimummaterial conditions, thereby, governingthe maximum Spline partisthinwalled. or tubular. or heat is desirable to Itry the 'NOGOI'gagein at least two places 90 degrees ] part. for example. may enter the'NOGO" gage at the low point, but notthe high. Ovality reduces the chances ofgetting the full use of all the teeth in thefinal assembly.

5 At this point a few defini-tions would be in order. (See Fig. 2).Profile Variation:Deviationfromspecified Involute profile normal to theflank surface with zere established at thepitch line. Positive errors reduce clear-ance or increase interference. Negativeerrors increase clearance and reduce con-tact Variation:The differencebe-tween the actual and true spacing of anytwo teeth, adjacent or Tooth thickness :The spacewidth of a perfect mating internal splinefor afitwithout looseness or int' Tooth thickness :The actualmeasured tooth thickness on the pitchline whichisequivalent to theeffecnvetooth thickness . less width allowance forprofile and index "GO"composite Spline gage isused to inspect the effective tooththickness down to the form diameter,These gages mustbevery precise.

6 Sincethey are used as the perfect matingmember, and any tolerances allowedwould steal. from the part ~NO GO" sector ring gage con-talning opposing sectors of about twoteeth is used to check the minimumactual tooth these gages requires a degree ofmanual dexterity. The"GO" gage needsto be triedinonly one angular some skill is required to start 'theAUTHORS:MR. ]NCKis 'lechnicalManager for tlcle ITW-lIIitronDivision ofllIinois Tool Works Inc. He has beenirlvolvedin the desigJl and application of many typesof metal cutting tools art>Qof tooling and gaging for the manufacturl:' ofgt>ar:s,splines and sprockets of both gf!

7 !leratingand fanning types. HewasChief Engineer andManager of Product Engineeringfrom 1979through1984for the Illinois Eclipse has served on various committees of theAGMAand MCTI and is Chainnan of theAGMAC utting Tool Inool'uteSp1imCom-mit:tee and the ASME-AN51 CommitteeorlPower Transmission Chail'15and Sprock:ets. Hehas written several articles on tooling subjecfsand has spoken at various SAE, 5ME, A5 QCandAGMA meetings. He was educated' been a staffmemberof the lTWcorporatemachinedevelopment group for10years. Subsequentlyhebecame supervisor ofthegroup. fiehClSbeen respol'15ible for the designorprojectmanagement of a wide variety of eq,uipmfmtrelating tonewproduct entryorproductivityimprovementfor manufacture and undenJ)ater cablehandling, He currently specializes in iJ15pectionil'15trument ITW.

8 His design development ofnew .Dusinessmachi11esforBell {:, Northrop(HalIicrafters) .He holds a Bachelor of Science .degreeinMechanical Engineering from Purdue Univer-sity and is a member of the American Societyof Mechanical Engineers,MarchjAprfll ,AJ'OR01, (FORSMALLDIAMETERSPLINES,USEMEASU'REMENT SWITHTHREEPIN,S)d I~ 'i}- f-- ---+--+1$GO-I~~~~I-~*Nor GOCIRCULAF'ISPACE , NOT GO SECTORPLUGGAGEOR MEASUREMENTBETwEENREFERIENCEDIMENSION(ME ASUREMENTBETWEENPIN,SINOT GO COMPOSITEPLUGGAGEGO COMPOSITEPLUGGAGETHE PUFECTeKTERN"" +'-'--'--EHECTIvESPACEWI DT HEQUALSTOOTHTHICKNESSOFPERFECTEXTERNALSP LINETHE 'peu CTUT'ERN ..l Spline FITS IN ""NY POSITION,IF ALL SPAC,ES Ale WIDENEDBYTHE""""OUNTOF Tli EINTEAFU[ NT,EFlNAlEACH SPACEIS.)]

9 $IC OF VARIATIONSON INTERNALSPUNECIRCULARTOOTH THICKNESSMAX-EFFECTIVEGO COMPOSITERING GAGEMINEFFECTIVIENorGO COMPOSITERIINGMAXACTUALREFERHICEDIMENSIO N(MEASUREMENTOVERIPIN,slMINNOT GOSECTORRINGGAGEOR MEASUREMENTOilERPINSACTUALCTUALTOOTH'THI CIKNESSEFFECTIVETOOTHTHICKN' SPACE WIDTHOFPERFECTINTERNALSPLIN,IET HfPERF'ECTINTf RNAlSPLINEfITSIN""NY POSITION,IFAU NARROWEDBY fHE AMOUNTOF THE OF VARlATIONSON EXTERNAL 'IACIRCULARTOOTHTHICKNESS'X ..fr. tz-RE' into the gage , especially part and gage is won't enter ful1y, it is classed as anoversize reject. The" its limited teeth and usual non entrysituation,is more difficult to with the difficuJtyinuse, industrystandards for this check are not consis-tent for either the number of places,whichconstitute a reject, nor for theforce required to attain obvious that the use of"GO"and"NOGO"gages is tediousand laborand skillintensive.)

10 Another element necessary to consideris gage weal'.Allowancesan! made forthis in making a new gage . Periodicallyactive gages must be monitored for be done with measurementbe-tween pins, but usually a tapered masterplug is used. (See iFig. 3). Etched linesalong the plug indicate the fit or wearrange, This means splines acceptedbyaworn gage mayberejected by a new gage tolerances an! planned toabsorb no more than 25%of the producttolerance ..Inpractice, bywayof asampling ofactual gages in active use,itwas found that the measured accuracy18'GearTecMology10------SPU N ELENGTH-------1 LEADW!EARDEPENDENTON OVER-SIZEALLOWANICE----LENGTH-RANGERANGE RINGGAGEwlTHllNFITRAN,G,Eyzxx,YYANDZZDET ERMINEDBY CALI,BRATIONof"GO"gages can absorb a many years, the span or blockmeasurement system for sizing involutegears and splines has been procedure using a micrometer of teeth.