Clamping and Clamping Devices

What does clamping mean in context of jigs and fixtures?
Principles of Clamping
Different types of Clamping Devices, their advantaged and disadvantages

1. Clamping
&
Clamping Devices

2. ClampingSystem
•Aclampingsystemmustholdtheworkpiecefirmlyagainstthe
locatingelementsandthecuttingforcesdevelopedduring
operationwithoutcausingdamagetoit.
•Speedofoperation,operatorfatigueandstrategicpositioningareconsideration
whiledesigningclampingsystem
•Clampingdeviceshouldbeincorporatedintothejigorfixture,properclampingin
afixturedirectlyinfluencetheaccuracyandqualityoftheworkdoneand
productioncycletime.

3. PrinciplesofClamping
•Position
•Strength
•Productivity
•Operatorfatigue

4. PrinciplesofClamping
Position:
•Clampingsystemshouldbepositionedatthicksectionsoftheworkpiece.
•Clampingshouldbepositionedtodirecttheclampingforceonastrong,supported
partoftheworkpiece.
•Clampingonunsupportedpartbendsslenderworkpieces,affectsaccuracyof
operation.
•Clampingsystemshouldnotobstructloadingandunloadingoftheworkpiece.
•Clampingsystemshouldnotobstructthepathsofcuttingtool.
•Operatorshouldbeabletooperateclampseasilyandsafely
•Averticalholedrilledinthebentworkpiecewouldbecomeangularwhenthe
unclampedworkpiecespringsbacktoitsoriginalshape.
Distortion of unsupported
workpiece

5. •Clampingforceshallbedirectedtowardssupport/locators.
PrinciplesofClamping

6. •Clampshallbedirectlyinlinewiththesupport
PrinciplesofClamping

7. •Clampingforceshallbedirectedtowardssupport/locators.
PrinciplesofClamping

8. •Clampsshallapplyforceagainstsupportedareaofworkpiece
PrinciplesofClamping
Good
Bad

9. PrinciplesofClamping
Strength:
•Theclampingsystemshouldbecapabletoholdtheworkpiecesecurelyagainst
theforcesdevelopedduringoperation.
•Clamping device should be capable to be unaffected by the vibrations generated
during an operation.
•Theclampingforceshouldnotdentordamagetheworkpiecewithexcessive
pressure.
•Forclampingweakandfragileworkpiece,clampingforceshouldbeequally
distributedoverawiderareaoftheworkpiece.
•Whileclampingsoftworkpiece,clampsshouldbefittedwithpadsorsofter
materialssuchasNylonorFibretopreventdamageanddentingofthe
workpiece.
•Clamping faces should be hardened by proper treatments to minimize their
wearing out.

10. PrinciplesofClamping
Productivity:
•Clampingtimeshouldbeminimisedby
usinghandknobs,tommybars,knurled
screws,handwheelsandhandles,so
thatclampcanbetightenedorloosened
manuallywithoutusingspanners.
•Mostoftheclampsusehexagonalnutor
handnut
Hand operated clamping devices

11. PrinciplesofClamping
Hand operated clamping devices

12. PrinciplesofClamping
OperatorFatigue:
•Operatorfatigueshouldbetakenintoaccount.
•Clamping should be operator friendly.
•Clamping and releasing should be easy and less time consuming.
•Maintenanceshould be easy.
•Ifconsiderablenumberofclampsaretobetightenedorloosenedrepeatedly,itis
bettertousepneumaticorhydraulicclampingwhichreducesoperatorfatigue
andsavesclampingtime.
•Handnutsaremoreconvenientfortheoperatorthanhexagonalnutsbecausea
spannerisnotrequiredtotightenthem.

13. TypesofClamping
•MechanicalActuationClamps
•PneumaticandHydraulicClamps
•VacuumClamping
•MagneticClamping
•ElectrostaticClamping
•NonMechanicalClamping
•SpecialClampingOperations

14. TypesofClamps
•Screwclamps
•Strapclamps
•Pivotedclamps
•Hingedclamps
•Swingingclamps
•Quickactionclamps
•Powerclamps
•Non-conventionalclamps

15. MethodsofClamping
Clampingmethodandsystemarebasicallyoftwocategories:
1.Generaltypewithoutmuchconsiderationofthespeedofclampingoperations.
2.Quickactingclampingmethod/quickactionclamps.

16. ScrewClamps
•Theyarethreadeddeviceswithknurledcollar,handknob,Allenkeys,tommybar
orspannerflatsforrotatingandtighteningthescrew.
•Theyareusedforlightclamping.
Screw Clamp

17. ScrewClamps
•Theclampingareaofscrewisincreasedbyprovidingapad.
•Theclampingpadremainsstationaryontheworkpiecewhilethescrewrotates
andrubsontheconicalseatofthepad.
Floating Pad

18. ScrewClamps
•Afloatingpadisusedtopreventdamagetotheworkpiecebyallowingthescrew
torotateatthepointofclampingontheworkpiece.
•Theswiveltypeclampingpadprovidesasphericaljointbetweentheclamping
padandtheclampingscrew.
•Theswivellingpadadjustsitselftosuittheinaccuraciesintheclampingfaceof
theworkpiece.
•Thecrosspinengagesthepadwiththescrew.
Floating Pad

19. ScrewClamps
•Thedisadvantageofscrewclampis,theclampingpressurelargelydependsonthe
workpiece,itvariesfromoneworkpiecetoother.
•Itismoretimeconsumingandmoreeffortsarerequired.

20. ScrewClamps
Clamping Screw

21. ScrewClamps
Clamping Screw

22. ScrewClamps
Clamping Screw

23. ScrewClamps

24. Strap or Plate Clamps

25. Strap/Plate/BridgeClamps
•Itisverysimpleandreliableclampingdevice.
•Theclampingforceisappliedbyspringloadednut.
Strap Clamp

26. Strap/Plate/BridgeClamps
•Thesearemadeofrectangularplatesandactlikelevers.
•Theclampsaretightenedbyrotatingahexagonalnutonaclampingscrew.
•Oneendoftheclamppressesagainsttheworkpieceandtheotherendonthe
heelpin.
•Thetoei.e.clampingfaceoftheclampiscurvedandthepressurefaceoftheheel
pinismadesphericaltotakecareofanyvariationsintheworkpiece.
•Sphericalwasherspermitstheclamptotiltwithrespecttothescrewandthenut.
Simple Plate Clamp

27. Strap/Plate/BridgeClamps
•Strapclampsareprovidedwithawasherandspringbelowtheclamp.
•Thespringliftstheclampasthenutisloosenedandworkpiecebecomesfree.
•TheSpringholdstheclampinaraisedpositionduringloadingandunloadingof
theworkpiece.
•Washerpreventstheentryofthespringintheholeoftheclamp.
•Clampisrotatedaboutthestudtoreleasetheworkpiece.
Simple Plate Clamp

28. StrapClamp:WorkpieceVariation
•Theclampispreventedfromrotatingduringclampingbyprovidingpinatthe
heel-end.
•Theclampstudisusuallyatleast10mmindiameterandnearertothetoe-end
thanheel-endoftheclamp.

29. StrapClamp:WorkpieceVariation
•Theheelpinengagestheclampplatetopreventitfromrotatingduringclamping.

30. Strap/Plate/BridgeClamp
Bridge Clamp

31. RetractableStrapClamp
•Whenclampsfallinthepathof
loadingandunloading,theyare
madeslottedtopermitlinear
withdrawal.
•Theclampisretracedtotheposition
shownbychaindottedlineduring
loadingandunloadingofthe
workpiece.
•Slottedclampplatesothatthe
workpiececanbereleasedwithout
clamprotation.
•Adjustableheelpinisusedwhere
workpieceheightislikelytovary
moreconsiderably.
Slotted Strap Clamp with
adjustable heel pin

32. RetractableStrapClamp

33. “U”Clamp
•UClampcanberemovedaltogethertofacilitateloadingandunloadingofthe
workpiece.
U Clamp with open slot

34. TwoPointClamp
•Itisusedtoclamptwoworkpiecesortoclampasingleworkpieceattwo
locations.

35. SwingingStrapClamp
•Thistypeofclampcanberotatedby90
o
toclearthepassageforloadingand
unloadingtheworkpiece.
•Theclampisswungtothepositionshownbythechaindottedlineduringloading
andunloadingoftheworkpieces.
Swinging Strap Clamp

36. SpecialStrapClamp
•Theclampshapecanbechangedtosuittheworkpieceandtheoperation.
•Clampscanbemadeslottedincentretopermitpassageofthecutter.
Tool slot in clamp

37. SpecialStrapClamp
•Theclampshapecanbechangedtosuittheworkpieceandtheoperation.
•Circularandsymmetricalworkpiecescanbeclampedwellwithaspiderclamp
havingthreeclampingpoints,noheelpinisnecessary.
Spider Clamp or Three-point Clamp

38. SwingingStrapClamp
•Figureshowsa45
o
swingingdiagonal
clampdevelopedforclampingthe
workpiecetothejig.
•Theendsoftheclamparechamfered
toenableloadingandunloadingofthe
clamp.
•Thestoppinisfittedinthejigplate
facilitatebringingtheclampblindlyin
theclampingpositionand
loading/unloadingpositions.
•Theclampingboltisweldedtothe
clamptosimplifyswingingoftheclamp
alongwiththebolt.
Special swing clamp for drill jig for Terminal
Box holes in electrical motor body

39. •GooseneckClampcanreducetheclampheightwithrespecttotheworkpiece
height.
StrapClamp
Gooseneck Clamp

40. •StrapClampclampingtwoworkpieces
StrapClamp
Strap Clamp

41. StrapClamp:WorkpieceVariation
•Sphericalwashersareusedinpairs.Thesphericalseatofwasherstransmitsthe
clampingpressurefromthenuttotheclamp.
•Heelpinpressuresurfaceshouldalsobemadesphericaltopermitsometiltingof
theclamp.
•Misalignmentbetweentheclampsurfaceandtheclampingnutduetotiltingof
theclampcanbecounteredbyuseofsphericalwashersbetweentheclampand
thenut.
Clamping variable
workpieces

42. StrapClamp:WorkpieceVariation
Universal Clamp with cylindrical washer

43. Edge Clamps

44. EdgeStrapClamp
•EdgeClampsareusedforclampingworkpiecesontheedgesduringfacing
operationsorwhenonlyhorizontalsurfaceistobemachined.
•Tighteningofthehexagonalnutwedgestheclampbetweentheworkpieceand
theangularheelsurface.
Edge Strap Clamp

45. EdgeJawClamp
•Edgejawclampslidesdowntheinclinedheelasthehexagonalnutistightened.
•Tighteningofthehexagonalnutpushesthejawagainsttheworkpiecetoclampits
edge.
Edge Jaw Clamp

46. Pivoted Clamps

47. PivotedStrapClamp
•Clampsareoftenpivotedatthecentretosimplifytheiroperation.
•Theknurledheadedscrewisusedtoloosenandtightentheclamp.
Pivoted Strap Clamp

48. PivotedEdgeClamp
•Thepivotpinisnearertotheclampingpoint.
•Thescrewisshiftedtotheendoppositetheclampingpoint.
•Theclampingscrewbecomesmoreaccessibletotheoperator.
Pivoted Edge Clamps

49. PivotedTwo-wayClamp
•Pivotactioncanbeusedfortwo-wayclampingoftheworkpiece.
•Tighteningofthescrewmakesthecurvedsurfaceoftheclamptouchthe
workpieceandfurthertighteningofthescrewclampstheworkpiecevertically
andhorizontally.
•Two-wayclampalsopushestheworkpieceagainsttwolocators.
Pivoted Two-way Clamp

50. Hinged / Latch Clamps

51. HingedClamp
•Hingedclampprovidesrapidclearanceofthepassageforloadingandunloading.
•Itisclampedwithswingingeyebolt.Theclamphasopenslotthroughwhichthe
eyeboltcanbeswungintoposition.
•Tighteningofthehexagonalnutclampstheworkpiece.
•Forloadingandunloadingtheworkpiece,thehexagonalnutisloosenedhalf-a-
turnandtheeyeboltisswungoutoftheopenslottofreethehingedplate.
Hinged Clamp

52. HingedClamp
•Thelatchandthestudmovementsarecontrolled.
•Thelatchisinfullyopenpositionwhenthefacesindicatedby“X”areincontact.
•Handnutisusedtoclamptheworkpiece.

53. HingedTwo-wayClamp
•Theworkpieceispushedagainstthelocationpinsbythepivotededgeclamp
whichalsohousestheswingingeyebolt.
•Theknurlednutisusedtoclamptheworkpieceagainstthelocationpins.
•Workpieceisclampedintwodirectionbytheedgeclampandthepadinthe
hinge.
•Forloadingandunloadingtheworkpiece,theknurlednutisloosenedhalf-a-turn
andtheeyeboltisswungoutoftheopenslottofreethehingedplate.
Hinged Two-way Clamp

54. HingedClamp
Hinged Clamp with pivoted clamping block

55. HingedClamp
•Two-wayclampisanextensionofthelatch-typeclamp.

56. ButtonClamps
•Thesemaybefixedatonepointorremovableasrequired.

57. C Washer

58. CWasher
•Itisastrapclampwithanopenslot.
•Itissimpleandquickinoperation.
•TheslotpermitsquickremovalofCWasherafteraslightlooseningofthe
hexagonalnut.
•TheCwasherisoftenchainedtothefixtureorpivotedaroundashoulderscrew
topreventitsloss.
•ThepivotshoulderscrewmakestheCwashercaptive.

59. SwingWasher
•Toloadorunloadtheworkpiece,thelockingnutisrotatedbygivingitaboutone
turn.
•ThestudandboltsizesareselectedinsuchamannerthatwhentheCClampis
removed,theworkpiececanfreelypassoverthenut

60. Swinging Clamps

61. SwingingClamps
•Thesesclampsareswungtotheposition.
•Theyrotateintheplaneoftheplate.
•Figuredepicttheswingingclamppivoted
abouttheshoulderscrew.
•Workpieceisclampedbyknurledhead
screw.

62. SwingingClamps

63. SwingingClamps
•Swinginglatchwithanopenslotatoneend..
•ThelatchisswungaroundpivotPattheotherend.
•ShoulderscrewSenterstheopenslotduringoperation.
•Theworkpieceisclampedbyknurledheadscrew.

64. SwingingClamps
•Typesoflatchesandtheirmethods
ofoperation.
•Chain-dottedlineshowsthelatches
intheirclearloadingandunloading
position.
•Shoulderscrewsareoftenusedas
pivotsforthrustpads.
•Theshoulderdiametermustbe
biggerthanthethrustdiameterso
thattheshoulderfaceactsasastop
whenthescrewistightened.

65. SwingingClamps
•SwingingclampwithCWasher

66. Quick Action Clamps

67. ToggleClamp
•Theyprovideconsiderabledistancefor
loadingandunloadingofthe
workpiece.
•TheCframeclampcanbeswungtothe
chaindottedpositionduringloading
andunloading.

68. ToggleClamp
•Thepusher-typetoggleclampwithdrawsbackwardsduringunclamping.
•Toggleclampsareprovidedwithclampingscrewstoaccommodateworkpiece
variations.

69. ToggleClamp

70. QuickTurnScrew/ThumbScrew
•Itisusedtoclamphingedjigplatesand
latcheswithinaquarterturn.
•Inunclampedpositionheadofthethumb
screwcanpassthroughtheslotprovidedin
thejig/latchplate.
•Theplatecanswungclearofthethumb
screwhead.
•Forclamping,thethumbscrewisturned
90
o
soitsheadisrightanglestotheslotin
theplate.
•Thematingsurfaceofthethumbscrew
headmustbefiledforproperclamping.
•Quarter-turnscrewsaresuitableforlight
loadsonly.
•Forheavyloads,swingingeyeboltandknob
combinationisused.

71. QuickActionHandNut
Cast Hand Nut
•Theyareavailablewiththemanufacturersofstandardparts.
•Casthandnutsaremoreconvenientandlessexpensivethantheturnednuts

72. Cam
•Quickclampingbycamisveryeffectiveandverysimpleinoperation.
•Thecamtypeclampingsystemisusedforclampingthroughsomeinteriorparts
whereothersimplesystemwillnothaveaccess.

73. Cam
•Camshiftsitsmatingsurfacestoclamporunclamptheworkpieces.

74. Multiple Clamping

75. DoubleClamping
•Twoworkpieceswithlimitedvariationcanbeclampedbyasinglestrapclamp.
•Thesphericalwashersareprovidedbetweenthenutandtheclampwhichallow
theclamptotiltslightlytosuitthevariationinthetwoworkpieces.

76. Equaliser
•Clampispivotedaroundapin.
•Equaliserclamppivotstosuitthevariationintheworkpieces.
•Equaliserprinciplecanbeextendedtoclampmorethantwoworkpieces.

77. Equaliser
•Inmultipleclamping,apivotedequaliserisusedforclampingtwounequal
workpiecessimultaneously.
•Apivotpinisusedtopivottheequaliser.
Equaliser for two workpieces

78. Equaliser
Equaliser for two workpieces

79. Equaliser
•Manyevennumberofworkpiecescanbeclampedsimultaneouslybyasingle
clamp.
Equaliser for four workpieces

80. Equaliser
•Onlyanevennumberofworkpiecescanbeclampedbyanequaliser.
Equaliser for two workpieces
Equaliser for four workpieces

81. Stacking
•Workpiecescanbestakedtogetherandtheentirestackcanbesecuredbyasingle
clamp.
•Workpiecescanbesandwichedbetweenlocatorsandthemulti-layeredsandwich
canbesecuredbyasingleclamp.
•Alltheworkpiecesareclampingtogetherbyhexagonalheadboltandoneendof
thefixture.

82. Stacking
•Instringmillingfixture,roundworkpiecesaresandwichedbetweenVlocators.

83. Power Clamping

84. PowerClamping
•Powerclampingisusedtosimultaneouslyoperateanumberofclamps.
•Powerclampingcanbebroadlydividedintothefollowingcategories:
•Fluidpowerclamping
oPneumaticclamping
oHydraulicclamping
•Vacuumclamping
•Magneticclamping
•Electrostaticclamping

85. Summary:PrincipleofClamping
•Positonclamponstrongsupportedpartoftheworkpiece,clearoftheworkpiece
loading/unloadingandcuttingtoolpaths.
•Clampstrengthshouldbeadequatetowithstandoperationalforceswithout
damagingtheworkpiece.
•Quickoperationwithoutspanner,levers,knobs.
•Pneumatic/hydraulicoperationforsimultaneousactuationofnumerousclamps.
•Compensationforvariationintheworkpiecethroughradiiatclampingpointand
ontheheelpin,useofsphericalwashersandequalisers.

86. References
1.JigandFixtureDesignManual,ErikK.Henrikson,IndustrailPress.
2.JigsandFixture,P.H.Joshi,THM.
3.AnintroductiontojigandtoolDesign,M.H.A.–Kempster,IIIEd.PubELBS.

87. Thank You!