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2. The University Of Lahore
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3. SHEET METAL FORMING PROCESSES
TOPIC

4. INTRODUCTION:
SHEET METAL FORMING is the process of
converting a flat sheet of metal into a
part of desired shape without fracture or
excessive localized thinning. The process
may be simple, such as a bending
operation, or a sequence of very complex
operations such as those performed in
high-volume stamping plants.

5.  Characteristics of sheet Metal.
 Formability Of Sheet Metal
 Tube Bending And Forming
 Bending Of Sheet And Plate
THERE ARE FOUR MAIN FOLLOWING
PROCESSES OF SHEET METAL FORMING.

6. CHARACTERISTICS OF SHEET METAL

7. SHEET METAL:
“SHEET METAL IS SIMPLY METAL FORMED INTO A THIN
AND FLAT PIECE CALLED A SHEET METAL.”

8. In prehistoric times, metal sheets were used to make
armor of soldiers, swords , canons, etc.
Before the discovery of Glass, it was also used to
make common home articles like plates, bowls, liquid
jars, etc.
Later on the sheet metal found its way in the making
of vehicles, blades of helicopters.
HISTORY OF SHEET METAL

10. Sheet metals are characterized by a high ratio of surface
area to thickness.
Sheet metal forming is basically conversion of a flat sheet
metal into a product of desired shape without defect like
fracture or excessive thinning.
WHY IS IT NECESSARY?

11. GENERAL METAL CHARACTERISTICS
Metals are… Solid at room temperature, except
mercury, which is liquid !
Metals have…Very high melting point.
Metals are… Shiny when they cut.
Metals are… Good conductors of heat and electricity.
Metals are… Usually strong & malleable so they can be
hammered into shape.

12. Sheet metal parts are usually made by forming
material in a cold condition , although many sheet
metal parts are in a hot condition because the
material when heated has a lower resistance to the
deformation.
Spring or blanks are very often used as initial
materials, and are formed on press using
appropriate tools. The shape of the part generally
corresponds to the shape of tool.
Intro to Sheet Metal Characteristics:

13.  Elongation -This is the characteristic of the sheet
metal to stretch without necking and failure.
Strength - The ability of a material to stand up to
forces being applied without bending, breaking or
deforming it in any way.
 Elasticity - The ability of a material to absorb force
and flex it in different directions, returning to its
original position.

14.  Plasticity - The ability of a material to
change in shape permanently.
 Ductility - The ability of a material to
change shape (deform) usually by
stretching along its length.

15.  Toughness - A characteristic of a material that
does not break or shatter when receiving a
blow or under a sudden shock.
 Conductivity - The ability of a material to
conduct electricity.

16.  Tensile Strength – The ability of a material
to stretch without breaking or snapping.
 Grain Size – Determines surface roughness
on stretch sheet metal. It affects material
strength.
 Anisotropy –Determine thinning behaviour
0f sheet metal during stretching; important
in deep drawing operation.

17.  In automobiles: The sheet metal is deformed into
the desired and brought into the required form to get
auto body pressings like
bonnet, bumpers, doors, etc.
 In aircraft’s: Sheet metal is used for making the
entire fuselage wings and (body).
 In domestic applications: Sheet metal is used for
making many parts like washing machine body and
covers, iron tops, clock cases, fan blades and
casing, cooking utensils etc.
Applications of Sheet Metal:

19. FORMABILITY OF SHEET METAL
TOPIC:

20. DEFINITION:
“The ability of the sheet metal to
undergo the desired shape change
without such failure as necking or
tearing.

21. TESTING METHODS FOR FORMABILITY
We can determine the formability of
the sheet metal by following tests.
DUCTILITYTEST
DENT TESTER
TENSILETEST
CUPPING TEST

22.  DUCTILITY TEST
 Good ductility tests are in great demand for
thin sheet.Typical forming procedures such
as deep drawing and stretch forming are
characterized in standardized test methods .
It is an important but complex test is the
determination of the forming limit
curve, from which designers can
derive limit strains which should not be
exceeded during forming processes.

23. DIAGRAM OF DUCTILITY TEST

24. TENSILE TEST

25.  TENSILE TEST:
 Tensile testing is the most basic mechanical test
for sheet metal. Tensile testing is relatively
simple and inexpensive. It also follows
established standards to ensure uniformity of
application and results suitable for comparison.
Simply put a standardized sample in tensile test
apparatus an pull it along a single axis until it
fails. We measure the material as it is pulled to
determine the material's elongation, tensile
strength, yield strength, and the range of
engineering stress and strain.

26. DIAGRAM OF TENSIL TEST

27. CUPPING TEST

28.  CUPPING TEST:
The very first test is the cupping
test, for checking the formability of
sheet metals. In which test the sheet
metal specimen is clamped between two
circular flat dies, and a steel ball
or round punch is pushed hydraulically
into the sheet metal until a crack
begins to appear on the stretched
specimen.

29. Formability of
sheet metal is
directly
proportional to
the punch depth
“d”. This test is
insufficient in
simulating exact
conditions of
actual sheet-
forming
operations.

30. DIAGRAMS OF CUPPING TEST

31. DENTER TEST

32. DentTester:
The DentTester is an
important part of the steel producer’s
formability testing. Its primary function is
testing for dent resistance.A punch applies
forces up to 1,100 lbs., speeds up to 100
inches/second and a punch travel of 2". A
large work area of 10' by 12' enables the dent
tester to accommodate full size automotive
panels or sheet stock for testing.

33. DIAGRAM OF DENT TESTER

34. TUBE BENDING AND FORMING
TOPIC:

35. DEFINITION :
“ IT IS A METAL FORMING PROCESS USED
TO PERMANENTLY FORM PIPES OR
TUBING INTO THE SHAPE OF A DIE.”

36.  Press Bending
 Rotary Draw Bending
 Heat-Induction
 Roll Bending
 Sand-Packing
TYPES OF TUBE BENDING

37. PRESS BENDING

38. “It is the process in which a die in the shape of the
bend is pressed against the pipe forcing to fit the
shape of the bend.”
PRESS BENDING

39. DIAGRAM OF PRESS BENDIING

40. ROTARY BENDING

41. “The process in which a bend is formed by
drawing the work piece around a rotating bend
former.”
ROTARY DRAW BENDING:

42. DIAGRAM OF ROTARY DRAW BENDING

43. HEAT INDUCTION BENDING

44. “In this process an induction coil is placed
around a small section of the pipe at the bend
point. It is then heated between 430 TO 1,200
C. While the pipe is hot, pressure is placed
on the pipe to bend it. The pipe is then
quenched with either air or water spray”
HEAT INDUCTION:

45. DIAGRAMS OF HEAT INDUCTION

46. Roll Bending

47. “During the roll bending process the pipe is
passed through a series of rollers that apply
pressure to the pipe gradually changing the
bend radius in the pipe.”
This method of bending causes very little
deformation in the cross section of the pipe.
This process is suited to producing coils of pipe
as well as long gentle bends like those used in
truss systems.
ROLL BENDING:

48. DIAGRAMS OF ROLL BENDING

49. “In the sands packing process, the pipe is
filled with fine sand and the ends are
capped. The pipe is then heated in a
furnace to 1,600 F (870 C) or higher.
The pipe is then placed on a slab with
pins set in it. The pipe is then bent around
the pins using any mechanical force.”
The sand in the pipe minimizes distortion
in the pipe cross section.
SANDS PACKING:

50. DIAGRAMS OF SAND PACKING

51. ADVANTAGES OF TUBE BENDING
Exceptional accuracy and repeatability
Round and square tube capabilities
Mandrel bending
Bending is a cost effective process when used
for low to medium quantities.

52. Comparison:
Press Bending Heat Induction
Bending
 No heating is required Bending is done after heating
 It is used for smaller pipes It is used for larger pipes
 Mandrel is used. Mandrel is not used.
 More force is required Less force is required

53. YAMAHA & HONDA:
In the making of Handles of bikes.
SUZUKI,TOYOTA & HONDA:
In the making of Exhaust pipes.
APPLE FURNITURE INDUSTRIES:
In the making of chairs and tables
,etc.
SUPER ASIA:
In sanitary products.
APPLICATIONS OF TUBE BENDING.

54. BENDING OF SHEET & PLATE
TOPIC

55. “Bending is a manufacturing process that
produces a V-shape, U-shape, or channel
shape along a straight axis in ductile
materials, most commonly sheet metal.”
BENDING OF SHEET METAL:

56.  ROLL BENDING
 AIR BENDING
 BOTTOMING
 COINING
 FOLDING
 WIPING
 ROTARY BENDING
TYPES OF SHEET & PLATE BENDING

57. A Roll bending is that process in which three
rollers used to form a metal bar into a circular arc.
The rollers freely rotate about three parallel
axes, which are arranged with uniform horizontal
spacing.Two outer rollers, usually immobile, cradle
the bottom of the material while the inner
roller, whose position is adjustable, presses on the
topside of the material. Roll bending may be done
to both sheet metal and bars of metal.
ROLL BENDING:

58. DIAGRAMS OF ROLL BENDING

59. AIR BENDING

60. Air bending is the process in which the punch
touches the work piece and the work piece does
not bottom in the lower cavity. As the punch is
released then work piece springs back a little
ends up with less bend than that on the punch.
Spring back is usually 5 to 10 degrees in this
process.
Air Bending:

61. DIAGRAM OF AIR BENDING

62. BOTTOMING

63. It is a process where the punch and the work piece touches
the bottom of the die. This makes a controlled change of
angle with very little spring back. The inner radius of work
piece should be a minimum of a 1 material thickness.
In bottom bending, spring back reduced by setting the final
position of the punch. Such that the clearance b/w the
punch and die surface is less than the blank thickness. As a
result, the material yield slightly and reduces the spring
back. Bottom bending requires consequently more force
about 50%-60% more than air bending.
BOTTOMING:

64. DIAGRAMS OF BOTTOMING

65. “Coining is a bending process in
which the punch and the work piece
bottom on the die and compression
stress is applied to the bending region
to increase the amount of plastic
deformation. This reduces the amount
of spring back. The inner radius of the
work piece should be up to .75 of the
material thickness.”
COINING:

66. DIAGRAMS OF COINING

67. A rotary bending die is a special type of punch die
combination which bends the sheet metal using a
rotating cylinder with a v opening cut into the side of
the cylinder. The cylinder is seated into a saddle
making up the punch section of the die. The sheet
metal lays on an anvil and the rotary die is pushed down
on top of it. As the die engages the sheet it begins to
rotate and bends the metal around the tip of the anvil.
The rotary die will clamp the sheet metal before
bending providing a secure work piece without any
sliding. Rotary dies can also bend beyond 90 ° like
traditional tooling to compensate for Spring Back.
ROTARY BENDING:

68. DIAGRAMS OF ROTARY BENDING

69. “In this process one edge of the sheet is bent
to 90 degree while the other end is restrained
by the material itself and by the force of bank
holder and pad. The flange length can be
easily changed and the bend angle can be
controlled by the stroke position of the punch”
WIPING:

70. DIAGRAMS OF WIPING

71. “In folding, clamping beams hold the longer
side of the sheet. The beam rises and folds the
sheet around a bend profile. The bend beam
can move the sheet up or down, permitting the
fabricating of parts with positive and negative
bend angles.”
Folding:

72. DIAGRAMS OF FOLDING

73. Comparison:
Air Bending Bottoming Coining
 Spring back is more Spring back is less No spring back
 Work piece doesn't
touches the bottom of
the die
Work piece touches the
bottom of the die
Work piece touches the
bottom of the die
 Bend angles are
determined by the
punch stroke
Setup of the die is
changed to change the
bend angle
Setup of the die is
changed to change the
bend angle
 Less force is required Relatively more force is
required
Greatest force required
among all

74. SUPER ASIA :
Outer body of Room Coolers and Geysers.
G.F.C & ROYAL FANS :
Blades of Fan.
AUTOMOBILE INDUSTRIES :
Toyota, Honda & Suzuki.
RAFFLES:
CPU Casings.
PEL & DAWLANCE:
In the outdoors units of A.C.
APPLICATIONS OF SHEET METAL
BENDING IN PAKISTAN:

75. THANK YOU
THE END