This document discusses various sheet metal forming processes and operations. It describes how sheet metal is produced by rolling metal into thin sheets less than 6 mm thick. Common applications of sheet metal include aircraft bodies, automobile bodies, and household utensils. The document outlines various cutting, bending, drawing, and forming operations used to shape sheet metal, including shearing, punching, bending, deep drawing, spinning, and roll forming. It also discusses defects in forming processes and components of dies used in sheet metalworking.

1. Singh Abhishek Ravinder
141080119052
Semister-4rd
Mechanical Dept.
MANUFACTURING PROCESS II
GROUP NO:. 9

2. SHEET METAL FORMING
AND OPERATIONS

3. 1.0 Introduction
 Sheet metal is simply metal formed into thin and flat pieces.
 Sheet metal is essentially metal pressed into sheets. These sheets are used at various
places. These sheets can be bent, cut and molded into any shape for use anywhere.
 Sheet metal is generally produced in sheets by reducing the thickness of work piece
by compressive forces applied through a set of rolls.
Sheets

4. Sheet Metal Forming
How to differentiate a sheet and a
plate ?
OIf thickness is less than 6 mm (1/ 4
inches) then it is regarded as sheet.
OIf thickness is greater than 6 mm (1/
4 inches) then it is regarded as
plate.

5. Applications of sheet metals
O Aircraft Bodies
O Automobiles bodies
O Utensils used for domestic purposes
O Beverage cans

6. Cutting Operations
Shearing by two sharp cutting edges.
Plastic deformation penetration fracture

7. Shearing, Blanking and
Punching
Shearing - Cutting on sheet-metal with
straight edges.
Blanking - Cutting sheet-metal with a closed
contour.
Punching - Making holes on sheet-metal.

8. Sheet-metal Cuttingc = at
c = clearance
a = allowance
t = thickness
Blanking:
Blanking punch dia. = Db-
2c
Blanking die dia. = Db
Punch
Hole punch dia. = Db
Hole die dia. = Db+ 2c

9. Sheet-metal Cutting
Small clearance
Large clearance
Cutting force = StL
S = Shear strength of sheet-metal
t = Sheet-metal thickness
L = Length of cutting edge
or, Cutting force = 0.7TtL
T = Ultimate tensile strength of sheet-metal

10. Sheet-metal Cutting
Operations
Cut-off
Parting
Slotting Perforating Notching / Seminotching

11. Sheet-metal Cutting
Operations
Fine blanking -
close
tolerances and
smooth edges
in one step.
Trimming - Cutting operation to remove excess metal
Shaving - Shearing with very small clearance to obtain accurate
dimensions., secondary or finishing operation.

12. Bending
V- bending Edge - bending

13. Bending Analysis
BA = 2  A( R + Kbat ) / 360
where BA = bending allowance, A = bend angle, R = bend
radius, t = stock thickness, Kba = stretch factor.
For R< 2t, Kba= 0.33 ; for R 2t, Kba= 0.5.
Spring back,
where A’ = include angle of sheet-metal part
A’b = include angle of bending tool
w = width of sheet-metal
Bending force D = die opening dimension
Kbf = 1.33 V-bending
Kbf = 0.33 edge bending
b
b
A
AA
SB



D
TwtK
F
bf
2


14. Bending Analysis
Spring back
Die-opening
dimension

15. Bending Operations
Straight flanging Stretch flanging Shrink flanging
Hemming Seaming Curling

16. Bending Operations
Channel bending U-bending air-bending
Offset-bending Corrugating Tube forming

17. Drawing
c = Clearance
Db = blank
diameter
Dp = Punch
diameter
Rd = die corner
radius
Rp = Punch
corner
radius
F = drawing
force
Fh = holding
force

18. Deep Drawing
Initial step bending of edge straightening of side wall
Thinning and drawing final cup shape

19. Drawing Defects
a)Wrinkling in flange - small holding force
b) Wrinkling in the wall - insufficient holding force,
wrinkling initially occurring on the flange.
c) Tearing - high stress, sharp die radius
d) Earing - anisotropy of the material
e) Surface scratches - Die or punch not having a
smooth surface, insufficient lubrication

20. Other Sheet-metal Operations
Ironing - squeezing and
drawing in conjunction
Corning & Embossing - to
produce surface details
Lancing - combination of
cutting and forming

21. Other Sheet-metal Operations
Rubber forming
processes:
Guerin process - low
cost, small volume,
pressure up 10 MPa.
Hydroforming - Higher
pressure, up to 100
MPa.

22. Dies
Components of a punch and die for blanking operation

23. DIE CUTTING
OIt is combination of following operations
OPerforating.
OParting or shearing a sheet into two.
ONotching or removing pieces in edges.
OLancing or leaving a tab with removing any
material

24. SLITTING
OShearing operation –using circular blades
OThese blades follow straight line or circular path
or curved path – depending upon requirement.

25. NIBBLING
ONibbler (tool) move straight up and moves down
rapidly.
OSheet metal is fed in gap between two cutting
tools and produces overlapping holes
OSuitable small runs, several intrcate shapes can
be produced.

26. PIERCING
O It is a shearing operation.
O Creates open hole in sheet metal by
separating the interior section.
O Removed metal is discarded as scrap
PART
slug

27. BLANKING:
O It is also a shearing operation.
O It enlarges earlier pierced hole.
O Removed metal is desired one.
PARTPART
SLUG

28. OVery smooth and square edges can be obtained
by fine blanking.

29. Dies
Progressive
dies and final
part

30. Press
Press are driven mechanically or
hydraulically.
Knuckle jointcrankshaft
eccentric

31. Stretch Forming
Stretching and forming with a die at the same time.

32. Roll Forming Similar to the
the rolling
process but
working on
sheet-metal or
tubes.

33. Spinning
Conventional
spinning
Shear spinning - thinning and
bending occur at the same
time.

34. Spinning
Tube spinning - similar to shear spinning but working on
a tube.

35. High Energy Forming
Explosive forming
Electrohydraulic forming
Electromagnetic forming

36. Tube Bending
Stretch bending
Drawing bending
Compression bending
R/D  3.0 with mandrel
R/D  1.5 without mandrel