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Clamping
&
Clamping Devices
Clamping System
• A clamping system must hold the workpiece firmly against the
locating elements and the cutting forces de...
Principles of Clamping
• Position
• Strength
• Productivity
• Operator fatigue
Principles of Clamping
Position:
• Clamping system should be positioned at thick sections of the workpiece.
• Clamping sho...
• Clamping force shall be directed towards support / locators.
Principles of Clamping
• Clamp shall be directly in line with the support
Principles of Clamping
• Clamping force shall be directed towards support / locators.
Principles of Clamping
• Clamps shall apply force against supported area of work piece
Principles of Clamping
Good Bad
Principles of Clamping
Strength:
• The clamping system should be capable to hold the workpiece securely against
the forces...
Principles of Clamping
Productivity:
• Clamping time should be minimised by
using hand knobs, tommy bars, knurled
screws, ...
Principles of Clamping
Hand operated clamping devices
Principles of Clamping
Operator Fatigue:
• Operator fatigue should be taken into account.
• Clamping should be operator fr...
Types of Clamping
• Mechanical Actuation Clamps
• Pneumatic and Hydraulic Clamps
• Vacuum Clamping
• Magnetic Clamping
• E...
Types of Clamps
• Screw clamps
• Strap clamps
• Pivoted clamps
• Hinged clamps
• Swinging clamps
• Quick action clamps
• P...
Methods of Clamping
Clamping method and system are basically of two categories:
1. General type without much consideration...
Screw Clamps
• They are threaded devices with knurled collar, hand knob, Allen keys, tommy bar
or spanner flats for rotati...
Screw Clamps
• The clamping area of screw is increased by providing a pad.
• The clamping pad remains stationary on the wo...
Screw Clamps
• A floating pad is used to prevent damage to the workpiece by allowing the screw
to rotate at the point of c...
Screw Clamps
• The disadvantage of screw clamp is, the clamping pressure largely depends on the
workpiece, it varies from ...
Screw Clamps
Clamping Screw
Screw Clamps
Clamping Screw
Screw Clamps
Clamping Screw
Screw Clamps
Strap or Plate Clamps
Strap / Plate / Bridge Clamps
• It is very simple and reliable clamping device.
• The clamping force is applied by spring ...
Strap / Plate / Bridge Clamps
• These are made of rectangular plates and act like levers.
• The clamps are tightened by ro...
Strap / Plate / Bridge Clamps
• Strap clamps are provided with a washer and spring below the clamp.
• The spring lifts the...
Strap Clamp: Workpiece Variation
• The clamp is prevented from rotating during clamping by providing pin at the
heel-end.
...
Strap Clamp: Workpiece Variation
• The heel pin engages the clamp plate to prevent it from rotating during clamping.
Strap / Plate / Bridge Clamp
Bridge Clamp
Retractable Strap Clamp
• When clamps fall in the path of
loading and unloading, they are
made slotted to permit linear
wi...
Retractable Strap Clamp
“U” Clamp
• U Clamp can be removed altogether to facilitate loading and unloading of the
workpiece.
U Clamp with open slot
Two Point Clamp
• It is used to clamp two workpieces or to clamp a single workpiece at two
locations.
Swinging Strap Clamp
• This type of clamp can be rotated by 90o to clear the passage for loading and
unloading the workpie...
Special Strap Clamp
• The clamp shape can be changed to suit the workpiece and the operation.
• Clamps can be made slotted...
Special Strap Clamp
• The clamp shape can be changed to suit the workpiece and the operation.
• Circular and symmetrical w...
Swinging Strap Clamp
• Figure shows a 45o swinging diagonal
clamp developed for clamping the
workpiece to the jig.
• The e...
• Gooseneck Clamp can reduce the clamp height with respect to the work piece
height.
Strap Clamp
Gooseneck Clamp
• Strap Clamp clamping two work pieces
Strap Clamp
Strap Clamp
Strap Clamp: Workpiece Variation
• Spherical washers are used in pairs. The spherical seat of washers transmits the
clampi...
Strap Clamp: Workpiece Variation
Universal Clamp with cylindrical washer
Edge Clamps
Edge Strap Clamp
• Edge Clamps are used for clamping workpieces on the edges during facing
operations or when only horizon...
Edge Jaw Clamp
• Edge jaw clamp slides down the inclined heel as the hexagonal nut is tightened.
• Tightening of the hexag...
Pivoted Clamps
Pivoted Strap Clamp
• Clamps are often pivoted at the centre to simplify their operation.
• The knurled headed screw is us...
Pivoted Edge Clamp
• The pivot pin is nearer to the clamping point.
• The screw is shifted to the end opposite the clampin...
Pivoted Two-way Clamp
• Pivot action can be used for two-way clamping of the workpiece.
• Tightening of the screw makes th...
Hinged / Latch Clamps
Hinged Clamp
• Hinged clamp provides rapid clearance of the passage for loading and unloading.
• It is clamped with swingi...
Hinged Clamp
• The latch and the stud movements are controlled.
• The latch is in fully open position when the faces indic...
Hinged Two-way Clamp
• The workpiece is pushed against the location pins by the pivoted edge clamp
which also houses the s...
Hinged Clamp
Hinged Clamp with pivoted clamping block
Hinged Clamp
• Two-way clamp is an extension of the latch-type clamp.
Button Clamps
• These may be fixed at one point or removable as required.
C Washer
C Washer
• It is a strap clamp with an open slot.
• It is simple and quick in operation.
• The slot permits quick removal ...
Swing Washer
• To load or unload the work piece, the locking nut is rotated by giving it about one
turn.
• The stud and bo...
Swinging Clamps
Swinging Clamps
• Theses clamps are swung to the position.
• They rotate in the plane of the plate.
• Figure depict the sw...
Swinging Clamps
Swinging Clamps
• Swinging latch with an open slot at one end..
• The latch is swung around pivot P at the other end.
• Sh...
Swinging Clamps
• Types of latches and their methods
of operation.
• Chain-dotted line shows the latches
in their clear lo...
Swinging Clamps
• Swinging clamp with C Washer
Quick Action Clamps
Toggle Clamp
• They provide considerable distance for
loading and unloading of the
workpiece.
• The C frame clamp can be s...
Toggle Clamp
• The pusher-type toggle clamp withdraws backwards during unclamping.
• Toggle clamps are provided with clamp...
Toggle Clamp
Quick Turn Screw / Thumb Screw
• It is used to clamp hinged jig plates and
latches within a quarter turn.
• In unclamped p...
Quick Action Hand Nut
Cast Hand Nut
• They are available with the manufacturers of standard parts.
• Cast hand nuts are mo...
Cam
• Quick clamping by cam is very effective and very simple in operation.
• The cam type clamping system is used for cla...
Cam
• Cam shifts its mating surfaces to clamp or unclamp the workpieces.
Multiple Clamping
Double Clamping
• Two workpieces with limited variation can be clamped by a single strap clamp.
• The spherical washers ar...
Equaliser
• Clamp is pivoted around a pin.
• Equaliser clamp pivots to suit the variation in the workpieces.
• Equaliser p...
Equaliser
• In multiple clamping, a pivoted equaliser is used for clamping two unequal
workpieces simultaneously.
• A pivo...
Equaliser
Equaliser for two workpieces
Equaliser
• Many even number of workpieces can be clamped simultaneously by a single
clamp.
Equaliser for four workpieces
Equaliser
• Only an even number of workpieces can be clamped by an equaliser.
Equaliser for two workpieces
Equaliser for f...
Stacking
• Workpieces can be staked together and the entire stack can be secured by a single
clamp.
• Workpieces can be sa...
Stacking
• In string milling fixture, round workpieces are sandwiched between V locators.
Power Clamping
Power Clamping
• Power clamping is used to simultaneously operate a number of clamps.
• Power clamping can be broadly divi...
Summary: Principle of Clamping
• Positon clamp on strong supported part of the workpiece, clear of the workpiece
loading /...
References
1. Jig and Fixture Design Manual, Erik K. Henrikson, Industrail Press.
2. Jigs and Fixture, P.H. Joshi, THM.
3....
Thank You!
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Clamping and Clamping Devices

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

Published in: Engineering
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Clamping and Clamping Devices

  1. 1. Clamping & Clamping Devices
  2. 2. Clamping System • A clamping system must hold the workpiece firmly against the locating elements and the cutting forces developed during operation without causing damage to it. • Speed of operation, operator fatigue and strategic positioning are consideration while designing clamping system • Clamping device should be incorporated into the jig or fixture, proper clamping in a fixture directly influence the accuracy and quality of the work done and production cycle time.
  3. 3. Principles of Clamping • Position • Strength • Productivity • Operator fatigue
  4. 4. Principles of Clamping Position: • Clamping system should be positioned at thick sections of the workpiece. • Clamping should be positioned to direct the clamping force on a strong, supported part of the workpiece. • Clamping on unsupported part bends slender workpieces, affects accuracy of operation. • Clamping system should not obstruct loading and unloading of the workpiece. • Clamping system should not obstruct the paths of cutting tool. • Operator should be able to operate clamps easily and safely • A vertical hole drilled in the bent workpiece would become angular when the unclamped workpiece springs back to its original shape. Distortion of unsupported workpiece
  5. 5. • Clamping force shall be directed towards support / locators. Principles of Clamping
  6. 6. • Clamp shall be directly in line with the support Principles of Clamping
  7. 7. • Clamping force shall be directed towards support / locators. Principles of Clamping
  8. 8. • Clamps shall apply force against supported area of work piece Principles of Clamping Good Bad
  9. 9. Principles of Clamping Strength: • The clamping system should be capable to hold the workpiece securely against the forces developed during operation. • Clamping device should be capable to be unaffected by the vibrations generated during an operation. • The clamping force should not dent or damage the workpiece with excessive pressure. • For clamping weak and fragile workpiece, clamping force should be equally distributed over a wider area of the workpiece. • While clamping soft workpiece, clamps should be fitted with pads or softer materials such as Nylon or Fibre to prevent damage and denting of the workpiece. • Clamping faces should be hardened by proper treatments to minimize their wearing out.
  10. 10. Principles of Clamping Productivity: • Clamping time should be minimised by using hand knobs, tommy bars, knurled screws, handwheels and handles, so that clamp can be tightened or loosened manually without using spanners. • Most of the clamps use hexagonal nut or hand nut Hand operated clamping devices
  11. 11. Principles of Clamping Hand operated clamping devices
  12. 12. Principles of Clamping Operator Fatigue: • Operator fatigue should be taken into account. • Clamping should be operator friendly. • Clamping and releasing should be easy and less time consuming. • Maintenance should be easy. • If considerable number of clamps are to be tightened or loosened repeatedly, it is better to use pneumatic or hydraulic clamping which reduces operator fatigue and saves clamping time. • Hand nuts are more convenient for the operator than hexagonal nuts because a spanner is not required to tighten them.
  13. 13. Types of Clamping • Mechanical Actuation Clamps • Pneumatic and Hydraulic Clamps • Vacuum Clamping • Magnetic Clamping • Electrostatic Clamping • Non Mechanical Clamping • Special Clamping Operations
  14. 14. Types of Clamps • Screw clamps • Strap clamps • Pivoted clamps • Hinged clamps • Swinging clamps • Quick action clamps • Power clamps • Non-conventional clamps
  15. 15. Methods of Clamping Clamping method and system are basically of two categories: 1. General type without much consideration of the speed of clamping operations. 2. Quick acting clamping method / quick action clamps.
  16. 16. Screw Clamps • They are threaded devices with knurled collar, hand knob, Allen keys, tommy bar or spanner flats for rotating and tightening the screw. • They are used for light clamping. Screw Clamp
  17. 17. Screw Clamps • The clamping area of screw is increased by providing a pad. • The clamping pad remains stationary on the workpiece while the screw rotates and rubs on the conical seat of the pad. Floating Pad
  18. 18. Screw Clamps • A floating pad is used to prevent damage to the workpiece by allowing the screw to rotate at the point of clamping on the workpiece. • The swivel type clamping pad provides a spherical joint between the clamping pad and the clamping screw. • The swivelling pad adjusts itself to suit the inaccuracies in the clamping face of the workpiece. • The cross pin engages the pad with the screw. Floating Pad
  19. 19. Screw Clamps • The disadvantage of screw clamp is, the clamping pressure largely depends on the workpiece, it varies from one workpiece to other. • It is more time consuming and more efforts are required.
  20. 20. Screw Clamps Clamping Screw
  21. 21. Screw Clamps Clamping Screw
  22. 22. Screw Clamps Clamping Screw
  23. 23. Screw Clamps
  24. 24. Strap or Plate Clamps
  25. 25. Strap / Plate / Bridge Clamps • It is very simple and reliable clamping device. • The clamping force is applied by spring loaded nut. Strap Clamp
  26. 26. Strap / Plate / Bridge Clamps • These are made of rectangular plates and act like levers. • The clamps are tightened by rotating a hexagonal nut on a clamping screw. • One end of the clamp presses against the workpiece and the other end on the heel pin. • The toe i.e. clamping face of the clamp is curved and the pressure face of the heel pin is made spherical to take care of any variations in the workpiece. • Spherical washers permits the clamp to tilt with respect to the screw and the nut. Simple Plate Clamp
  27. 27. Strap / Plate / Bridge Clamps • Strap clamps are provided with a washer and spring below the clamp. • The spring lifts the clamp as the nut is loosened and workpiece becomes free. • The Spring holds the clamp in a raised position during loading and unloading of the workpiece. • Washer prevents the entry of the spring in the hole of the clamp. • Clamp is rotated about the stud to release the workpiece. Simple Plate Clamp
  28. 28. Strap Clamp: Workpiece Variation • The clamp is prevented from rotating during clamping by providing pin at the heel-end. • The clamp stud is usually at least 10mm in diameter and nearer to the toe-end than heel-end of the clamp.
  29. 29. Strap Clamp: Workpiece Variation • The heel pin engages the clamp plate to prevent it from rotating during clamping.
  30. 30. Strap / Plate / Bridge Clamp Bridge Clamp
  31. 31. Retractable Strap Clamp • When clamps fall in the path of loading and unloading, they are made slotted to permit linear withdrawal. • The clamp is retraced to the position shown by chain dotted line during loading and unloading of the workpiece. • Slotted clamp plate so that the workpiece can be released without clamp rotation. • Adjustable heel pin is used where workpiece height is likely to vary more considerably. Slotted Strap Clamp with adjustable heel pin
  32. 32. Retractable Strap Clamp
  33. 33. “U” Clamp • U Clamp can be removed altogether to facilitate loading and unloading of the workpiece. U Clamp with open slot
  34. 34. Two Point Clamp • It is used to clamp two workpieces or to clamp a single workpiece at two locations.
  35. 35. Swinging Strap Clamp • This type of clamp can be rotated by 90o to clear the passage for loading and unloading the workpiece. • The clamp is swung to the position shown by the chain dotted line during loading and unloading of the workpieces. Swinging Strap Clamp
  36. 36. Special Strap Clamp • The clamp shape can be changed to suit the workpiece and the operation. • Clamps can be made slotted in centre to permit passage of the cutter. Tool slot in clamp
  37. 37. Special Strap Clamp • The clamp shape can be changed to suit the workpiece and the operation. • Circular and symmetrical workpieces can be clamped well with a spider clamp having three clamping points, no heel pin is necessary. Spider Clamp or Three-point Clamp
  38. 38. Swinging Strap Clamp • Figure shows a 45o swinging diagonal clamp developed for clamping the workpiece to the jig. • The ends of the clamp are chamfered to enable loading and unloading of the clamp. • The stop pin is fitted in the jig plate facilitate bringing the clamp blindly in the clamping position and loading/unloading positions. • The clamping bolt is welded to the clamp to simplify swinging of the clamp along with the bolt. Special swing clamp for drill jig for Terminal Box holes in electrical motor body
  39. 39. • Gooseneck Clamp can reduce the clamp height with respect to the work piece height. Strap Clamp Gooseneck Clamp
  40. 40. • Strap Clamp clamping two work pieces Strap Clamp Strap Clamp
  41. 41. Strap Clamp: Workpiece Variation • Spherical washers are used in pairs. The spherical seat of washers transmits the clamping pressure from the nut to the clamp. • Heel pin pressure surface should also be made spherical to permit some tilting of the clamp. • Misalignment between the clamp surface and the clamping nut due to tilting of the clamp can be countered by use of spherical washers between the clamp and the nut. Clamping variable workpieces
  42. 42. Strap Clamp: Workpiece Variation Universal Clamp with cylindrical washer
  43. 43. Edge Clamps
  44. 44. Edge Strap Clamp • Edge Clamps are used for clamping workpieces on the edges during facing operations or when only horizontal surface is to be machined. • Tightening of the hexagonal nut wedges the clamp between the workpiece and the angular heel surface. Edge Strap Clamp
  45. 45. Edge Jaw Clamp • Edge jaw clamp slides down the inclined heel as the hexagonal nut is tightened. • Tightening of the hexagonal nut pushes the jaw against the workpiece to clamp its edge. Edge Jaw Clamp
  46. 46. Pivoted Clamps
  47. 47. Pivoted Strap Clamp • Clamps are often pivoted at the centre to simplify their operation. • The knurled headed screw is used to loosen and tighten the clamp. Pivoted Strap Clamp
  48. 48. Pivoted Edge Clamp • The pivot pin is nearer to the clamping point. • The screw is shifted to the end opposite the clamping point. • The clamping screw becomes more accessible to the operator. Pivoted Edge Clamps
  49. 49. Pivoted Two-way Clamp • Pivot action can be used for two-way clamping of the workpiece. • Tightening of the screw makes the curved surface of the clamp touch the workpiece and further tightening of the screw clamps the workpiece vertically and horizontally. • Two-way clamp also pushes the workpiece against two locators. Pivoted Two-way Clamp
  50. 50. Hinged / Latch Clamps
  51. 51. Hinged Clamp • Hinged clamp provides rapid clearance of the passage for loading and unloading. • It is clamped with swinging eyebolt. The clamp has open slot through which the eyebolt can be swung into position. • Tightening of the hexagonal nut clamps the workpiece. • For loading and unloading the workpiece, the hexagonal nut is loosened half-a- turn and the eyebolt is swung out of the open slot to free the hinged plate. Hinged Clamp
  52. 52. Hinged Clamp • The latch and the stud movements are controlled. • The latch is in fully open position when the faces indicated by “X” are in contact. • Hand nut is used to clamp the workpiece.
  53. 53. Hinged Two-way Clamp • The workpiece is pushed against the location pins by the pivoted edge clamp which also houses the swinging eyebolt. • The knurled nut is used to clamp the workpiece against the location pins. • Workpiece is clamped in two direction by the edge clamp and the pad in the hinge. • For loading and unloading the workpiece, the knurled nut is loosened half-a-turn and the eyebolt is swung out of the open slot to free the hinged plate. Hinged Two-way Clamp
  54. 54. Hinged Clamp Hinged Clamp with pivoted clamping block
  55. 55. Hinged Clamp • Two-way clamp is an extension of the latch-type clamp.
  56. 56. Button Clamps • These may be fixed at one point or removable as required.
  57. 57. C Washer
  58. 58. C Washer • It is a strap clamp with an open slot. • It is simple and quick in operation. • The slot permits quick removal of C Washer after a slight loosening of the hexagonal nut. • The C washer is often chained to the fixture or pivoted around a shoulder screw to prevent its loss. • The pivot shoulder screw makes the C washer captive.
  59. 59. Swing Washer • To load or unload the work piece, the locking nut is rotated by giving it about one turn. • The stud and bolt sizes are selected in such a manner that when the C Clamp is removed, the work piece can freely pass over the nut
  60. 60. Swinging Clamps
  61. 61. Swinging Clamps • Theses clamps are swung to the position. • They rotate in the plane of the plate. • Figure depict the swinging clamp pivoted about the shoulder screw. • Workpiece is clamped by knurled head screw.
  62. 62. Swinging Clamps
  63. 63. Swinging Clamps • Swinging latch with an open slot at one end.. • The latch is swung around pivot P at the other end. • Shoulder screw S enters the open slot during operation. • The workpiece is clamped by knurled head screw.
  64. 64. Swinging Clamps • Types of latches and their methods of operation. • Chain-dotted line shows the latches in their clear loading and unloading position. • Shoulder screws are often used as pivots for thrust pads. • The shoulder diameter must be bigger than the thrust diameter so that the shoulder face acts as a stop when the screw is tightened.
  65. 65. Swinging Clamps • Swinging clamp with C Washer
  66. 66. Quick Action Clamps
  67. 67. Toggle Clamp • They provide considerable distance for loading and unloading of the workpiece. • The C frame clamp can be swung to the chain dotted position during loading and unloading.
  68. 68. Toggle Clamp • The pusher-type toggle clamp withdraws backwards during unclamping. • Toggle clamps are provided with clamping screws to accommodate workpiece variations.
  69. 69. Toggle Clamp
  70. 70. Quick Turn Screw / Thumb Screw • It is used to clamp hinged jig plates and latches within a quarter turn. • In unclamped position head of the thumb screw can pass through the slot provided in the jig/latch plate. • The plate can swung clear of the thumb screw head. • For clamping, the thumb screw is turned 90o so its head is right angles to the slot in the plate. • The mating surface of the thumb screw head must be filed for proper clamping. • Quarter-turn screws are suitable for light loads only. • For heavy loads, swinging eyebolt and knob combination is used.
  71. 71. Quick Action Hand Nut Cast Hand Nut • They are available with the manufacturers of standard parts. • Cast hand nuts are more convenient and less expensive than the turned nuts
  72. 72. Cam • Quick clamping by cam is very effective and very simple in operation. • The cam type clamping system is used for clamping through some interior parts where other simple system will not have access.
  73. 73. Cam • Cam shifts its mating surfaces to clamp or unclamp the workpieces.
  74. 74. Multiple Clamping
  75. 75. Double Clamping • Two workpieces with limited variation can be clamped by a single strap clamp. • The spherical washers are provided between the nut and the clamp which allow the clamp to tilt slightly to suit the variation in the two workpieces.
  76. 76. Equaliser • Clamp is pivoted around a pin. • Equaliser clamp pivots to suit the variation in the workpieces. • Equaliser principle can be extended to clamp more than two workpieces.
  77. 77. Equaliser • In multiple clamping, a pivoted equaliser is used for clamping two unequal workpieces simultaneously. • A pivot pin is used to pivot the equaliser. Equaliser for two workpieces
  78. 78. Equaliser Equaliser for two workpieces
  79. 79. Equaliser • Many even number of workpieces can be clamped simultaneously by a single clamp. Equaliser for four workpieces
  80. 80. Equaliser • Only an even number of workpieces can be clamped by an equaliser. Equaliser for two workpieces Equaliser for four workpieces
  81. 81. Stacking • Workpieces can be staked together and the entire stack can be secured by a single clamp. • Workpieces can be sandwiched between locators and the multi-layered sandwich can be secured by a single clamp. • All the workpieces are clamping together by hexagonal head bolt and one end of the fixture.
  82. 82. Stacking • In string milling fixture, round workpieces are sandwiched between V locators.
  83. 83. Power Clamping
  84. 84. Power Clamping • Power clamping is used to simultaneously operate a number of clamps. • Power clamping can be broadly divided in to the following categories: • Fluid power clamping o Pneumatic clamping o Hydraulic clamping • Vacuum clamping • Magnetic clamping • Electrostatic clamping
  85. 85. Summary: Principle of Clamping • Positon clamp on strong supported part of the workpiece, clear of the workpiece loading / unloading and cutting tool paths. • Clamp strength should be adequate to withstand operational forces without damaging the workpiece. • Quick operation without spanner, levers, knobs. • Pneumatic / hydraulic operation for simultaneous actuation of numerous clamps. • Compensation for variation in the workpiece through radii at clamping point and on the heel pin, use of spherical washers and equalisers.
  86. 86. References 1. Jig and Fixture Design Manual, Erik K. Henrikson, Industrail Press. 2. Jigs and Fixture, P.H. Joshi, THM. 3. An introduction to jig and tool Design, M.H.A. – Kempster, III Ed.Pub ELBS.
  87. 87. Thank You!

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