Drill jig

Drill jig, Cosiderations to design a drill jig, drill jig types

1. Drill Jig
•DrillJigDesignConsiderations
•DrillJigTypes

2. RequirementofaDrillJig
•Quickandaccuratelocationoftheworkpiece
•Easyloadingandunloadingoftheworkpiece
•Preventionofwrongloading
•Preventionofbendingormovementoftheworkpieceduringdrillingoperation
•Amplechipclearance
•Facilityforswarfremovalandcleaning
•Lightweighttominimiseoperatorfatigue
•Preventionoflossofpartsbyusingchains
•Clearanceforovershootofthedrill

3. General Considerations in the Design of Drill Jigs
Rigidity:
•Jig must be strong enough to withstand all forces applied to it.
•It must also resist deflections that may be the result of excessive tightening of
clamps that hold the w/p in place.
•The work must also be supported so that it does not bend under drilling pressure.
•Cast iron is generally used because it absorb shocks and compressive forces.

4. General Considerations in the Design of Drill Jigs
ChipControl:
•Typesofchips:segmentalandcontinuous.
•Thesegmentalchipispreferred.
•Spaceshouldbekeptbetweenthew/pandbottomofdrillbushingstoallow
chipstopassbetweentheworkandbusingplate(1-1/2*dia.ofdrill).
•Threewaysofchipremoval:coolant,manuallywithbrushorhook,compressed
air.

5. General Considerations in the Design of Drill Jigs
Jigfeetandlegs:
•Adrilljigshouldstandonfourfeet(Orlegs)ratherthanaflatsurface.
•Jigfeetmaybebuiltintothejigbodyorpurchasedasstandardparts.
•Theyareusuallyplacedontheextremitiesofthejigbody.
•Feetshouldbegroundsothattheyareallinoneplaneaftertheyaremountedon
thejigbase.

6. General Considerations in the Design of Drill Jigs
TypesofStandardJigFeet:

7. General Considerations in the Design of Drill Jigs
DrillingMachine/WearResistance/Loadingandunloading/Ejectionofw/p/
Coolantaccommodation:
•Thetypeofmachineinwhichoperationisperformedneedscareful
considerations.
•Thelayoutofthejigmustprovideadequatehandclearanceforeasilyloadingand
unloadingandprocessforloadingandunloadingmustbequick.
•Errorsariseincomponentsduetowear.Thereforewearresistancesurfaces
shouldbesmallandeasilyreplaceable.
•Toincreasetoollifeandkeepthecomponentscool,acoolantisprovidedin
cuttingedgeinsufficientquantity.Provisionsshouldbemadeforthecoolantto
gettothedrillandholesorpassagesforescapeofthecoolant.
•Designconsiderationsrequireeasyejectionofthecomponentfromjig
(particularlyforheavyones)tosavetheoperationtimeandincreasethe
productivity,pneumaticdevicesareverysuitableforeasyandquickejection.

8. General Considerations in the Design of Drill Jigs
Miscellaneousconsiderations:
•Sharpcornersshouldbeeliminated.
•Grippingsurfacesshouldbeknurled.
•Thejigshouldbelargeenoughtoholditagainstthetorqueofthedrilling
machine.
•Itmustbeeasytohandle.

9. DrillJig
•Jigswhichanbemanufacturedbyanyofthefollowingmethods:
oMachining
oForging
oCastingand
oWelding
•Normallyjigsaremadeofhardenedsteel,whicharewearresistant,corrosion
resistantandthermallyinsensitive.
•Theirdimensionalaccuracydirectlyinfluencestheaccuracyofperformanceofthe
operationswheretheseareused.

10. Types of Drill Jigs
•OpenJigs:
Usedforsimpleoperations.Workisdoneonlyononesideofthepart.
•ClosedorBoxJigs:
Usedforpartsthatmustbemachinedonmorethanoneside.

11. TypesofJigs
•Templatejig
•jigandchanneljigwithworkpiecepots
•Angleplatejig
•Turn-overjig
•Leaforlatchjig
•Boxjig
•Trunnion-typeindexingjig
•Sandwichandpumpjig
•Jigsformultispindlemachines

12. TemplateDrillJig
•Thisisasimpleplateofmetalorwoodwhichhasholesatcorrectlocationtobe
madeintheworkpiece.
•Sizeoftemplatejigissameasthatoftheworkpiece.
•Plateservesastemplatewhichisfixedandoverlappedwiththeworkpieceand
drillingisdonequickly.
•Useofthisjigavoidsthemarkingoperationcompletelyandtoimproveaccuracy.
•Itissimplesandleastexpensivetypeodjig.

13. TemplateDrillJig
•Theymayormaynothavebushings.Whenthebushingsarenotused,thewhole
jigplateisnormallyhardened.

14. PlateDrillJig
•Openjig.
•ItisenhancedformofTemplateJigwithjigbushesincorporatedinplate.
•Itconsistsofsinglebushplatewithprovisionforlocationandclampingof
workpiece.
•Theflatplatecontainingbushingistheirmainstructuralmember.Allthedetails
areattachedandreferencedtothisplate.
•Theyhavebuilt-inclampstoholdthework.
•Mayormaynothavelegs.
•Formassproduction.

15. PlateDrillJig
•Theplatejigislocatedandclampeddirectlyontheworkpiece.

16. PlateDrillJig
•Easyloadingandunloadingofworkpiece
•Chipremovalbyprovidingclearancebetweenplateandtheworkpiece.
•Thinpartsarestackedoneabovetheotherfordrillingatonetime.

17. PlateDrillJig
•Workpieceprofileislocatedbysixlocationpins.
•Workpieceprofileisclampedbytwoknurledscrewsagainstthelocationpins.

18. PlateDrillJig

19. TableJig
•Thisstyleiscalledtablejig.
•Thediameterofthejigfeetshould
bebiggerthantheslotofmachining
topreventthefeetfromfallinginto
theslots.

20. ChannelDrillJig
•Thecrosssectionofthejigresemblesachannel.
•Thecomponentisfittedwithinthechannelislocatedandclamped.
•Simplifieslocationandclamping.
•Fourlocationpinsandrectangularsurfaceforlocation.Singlescrewforclamping
•Drillisguidedthroughthedrillbush
•Theyareeconomical.

21. ChannelDrillJig
Channel Drill Jig
•Theworkpieceislocatedandclampedtoabasethatissuitableforanumberof
operations.

22. ChannelDrillJig
Channel Drill Jig
•Theworkpieceislocatedandclampedtoabasethatissuitableforanumberof
operations.

23. PotDrillJig
•Thereshouldbeenoughclearancebelow/
aheadoftheworkpiecefortheovershootof
thedrillafterpassingthroughthe
workpiece.
•Thepotisprovidedwithbiggerslotsforthe
passageofthedrilladdisposalofchips.
•Theseslotsarealignedwithdrillbushesin
thejigplatebyusinglocationpin.
•Alocationpinisprovidedinthepotanda
correspondingslotinthejigplate.
•Thepotisalsousedforanchoringthe
clampingstud.
•CWasherfacilitatesclampingofthe
workpiece.
Pot Drill Jig

24. PotDrillJig
•Theworkpieceislocatedfromits
outsideinabush.
•Theworkpieceisonlyplacedinthepot
tosupporttheflange.
•Drillplateislocateddirectlyinthe
workpiecebore.

25. AnglePlateJig
•Thelocatorsaregenerallyfixedtotheverticalwalloftheangularbody.
•Thecentrallocatorhasgrooveforthepassageofthedrillafterpassingthrough
theworkpiece.
•Thecylindricallocatoranddiamondpinlocatorarefixedtotheverticalwall.
•CWasherandhexagonalscrewisprovidedforclamping.
Angle Plate Jig

26. AnglePlateJig
Angle Plate Jig

27. Turn-overorTable-typeJig
•Workpiecehavingnosuitableresting
surfacefordrillingcanbedrilled
convenientlywithturn-overjig.
•Turn-overjigisplatejigwithjigfeet.
•Heightofthefeetshouldnelonger
thantheclampingstud.
•Turn-overjigisturnedoverforloading
andunloadingtheworkpiece.
•Afterloadingtheworkpiece,thejig
mustbeturnedovertorestonthejig
feetfordrilling.

28. Turn-overorTable-typeJig
•Commonlyusedforflangedworkpieces.
•Swarfclearanceisnotaproblem.
•Maindisadvantageisthelackofsupportbeneaththepointofcutting.

29. LeaforLatchJig
•Thisjighasanopenconstruction.

30. LeaforLatchJig
•Leafjighashingedjigplate.
•Drillbushesarefittedonthejigplatewhichishingedatoneend.
•Thejigplatecanbeswungasidetoprovideclearpathforworkpieceloadingand
unloading.
•Clampingscrewanddrillbushesareaccommodatedinjigpate.
•Thejigplatemusthavepositiverestingsurface.
•Thejigplateisclampedagainsttherestingfacebyaneyebolt.
•Quickclampingandunclampingofthejigplateispossible.
•Handknobisprovidedtofacilitateclamping

31. LatchJig

32. BoxJig

33. BoxJig
•Whentheholesaretobedrilledfrommorethanonefaceofthecomponent,
thereshallbemorethanonejigplate.
•Allthejigplatesshallbeassembledasaboxwithonesideopenforloadingand
unloadingofthecomponent.
•Oppositetoeachjigplate,thereshallberestingfeetprovided.
•Boxjigshallbeaslightaspossibletoenabletoliftandshiftagainandagain
•Someoftheclampsmayhavetotakethedrillingloadalso.

34. BoxJig
•Theboxisclosedandclampedby
thelatch.
•Suitablefeetareprovidedtogive
goodseating
•Suitableswarfclearanceportsare
incorporated.

35. Summary
•Agoodjigfacilitatespreciselocationandeasyfoolproofloading/unloadingof
theworkpiece.
•Itpreventsbendingoftheworkpiece.
•Ithasamplespaceforchipaccumulation.
•Itislightinweight.

36. Summary:
•Theworkpieceshouldbesupportedagainstbendingwhichoccursduetothe
downwardthrustofthedrill.
•Thejigandtheworkpiecearealsosubjectedtothrustinthedirectionofthefeed
ofthetool.
•Thereshouldbeenoughclearancebelow/aheadoftheworkpieceforthe
overshootofthedrillafterpassingthroughtheworkpiece.
•Locatingandclampingelementsindrilljigsaresubjectedtohightorqueinthe
directionperpendiculartotheaxisofthecuttingtool.

37. Summary:TypesofJigs
•Platejigsareusedfortheworkpieceshavingparallelmachinedfacesonsidesto
bedrilledandusedforresting.
•Turn-overortablejigsareusedforworkpieceshavingthemachinedsurfaceon
thesamesideastheholes.
•Leaforlatchjigsareusedforworkpieceshavingmachinedsurfaceontheside
oppositetotheholes.
•Boxjigsareusedfordrillingholesfromanumberofsidesonlightworkpiece.

38. References
•JigandFixtureDesignManual,ErikK.Henrikson,IndustrialPress.
•AnintroductiontojigandtoolDesign,M.H.A.–Kempster,IIIEd.PubELBS.
•JigsandFixture,P.H.Joshi,THM.
•JigsandFixture,ASTME.

39. Thank You!
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