This document discusses metal stamping processes and press working equipment. It describes various cutting and forming operations used in stamping like blanking, punching, and bending. Advantages of stamping include small weight, high productivity, accuracy and low cost. Press tools require components for working, structuring, guiding, feeding, locating and stripping the metal piece. Hydraulic presses use oil pressure to actuate the ram while mechanical presses use a crankshaft. Press tools are designed based on the required operation and method of working like simple, compound or progressive dies. Clearance is required between the punch and die to allow for material flow.

1. 1) Cutting operations.
a) Blanking
b) Punching
c) Notching
d) Perforating
d) Trimming
e) Shaving
f) Slitting
g) Lancing
2) Forming operations.
a) Drawing
b) Squeezing
c) Bending.

2. Stamping :
The work piece obtained after one or more press
operation is called a metal stamping.
Advantages of metal stamping
1) Small weight
2) High productivity (30000 to 40000 parts per 8 hr.)
3) High efficiency technique
4) Good accuracy
5) Low-Cost production
6) Predictable strength characteristics
7) Low cost material
8) Less labour consuming

3.  Elastic recovery or spring back
 Press Working equipment
1) Source of power
- Mechanical and Hydraulic.
2) Method of actuation of ram/rams.
- Ram is actuated by oil pressure
3) Number of slides
- Single acting
- Double acting
- Triple acting
4) Types of frame
- Open frame presses
- Close frame presses
5) Types of work for which the press has been designed
- Punching, Blanking ,Bending ,Forming, Coining,
Embossing.

4.  Mechanical press
Tonnage Capacity = Shear strength of crank shaft material x
the area of crank shaft bearing
 Hydraulic press
Tonnage capacity = Piston area x oil pressure in the cylinder

5.  Requirement of Press tool design
- Dimensional accuracy and surface finish
- Die and Punch must be strong
- Standard components are used for its
manufacture.
- Scrap in stamping operation must be minimum

6. a) Working component
b) Structural component
c) Guide component
d) Feeding comp.
e) Locating & locking
comp.
f) Stripping component
g) Fastening components

7. Press tool shank

8. 1) Back post design 2) Axial post design
3) Diagonal post design 4) Four guide post design

12. 1) According to types of press operation
a) Cutting dies.
These die are used to cut the metal
b) Forming dies.
These dies change the appearance of the blank without
removing any stock
2) According to method of operation
a) Simple dies.
Single operation for each stroke

13. b) Compound dies.
Two or more operations may be performed at one station.
Only cutting operation carried out. e.g. Washer

14. c) Progressive dies.
Object is formed by
single strokes on
More than one
Station.

15. d) Combination dies.
cutting operation is combined with a bending or
drawing operation at one station.

16. e) Transfer dies.
In transfer dies the already blanks are fed
mechanically from station to station.
f) Multiple dies.
Multiple dies produce two or more work piece
at each stroke of the press.

18. Brass and soft steel c = 5% of
t
Medium steel = 6 %
Hard steel = 7 %
Aluminium = 10 %
______________
C = 0.0032 *t *√shear strength (τs)
Reason behind the application of clearance

19.  For blank
Die opening size is made to the correct blank size
and the punch is made smaller an amount equal to
die clearance.
Die opening control the blank size.
 For Punching operation
Punch is made to the correct hole size and the die
opening is made oversize an amount equal to die
clearance.
Punch control the hole size.

20. Ram Driving mechanism
Crank and
Connecting rod
Crank
Connecting
rod

21. Pillar
Ram

22.  cutting forces
Cutting force for
circular blank Fmax = ∏ * D* t * τs.
Rectangular blank = 2(L+b)t * τs.
Energy or work done in press work
E= Fmax * punch travel
=Fmax * K * t.
Where K=percentage of penetration required to cause rupture.

23. Work done =Area under curve
= (maximum punch force) * (punch travel)
If shear on the cutting tool is zero
Punch travel= (% penetration)*(Material thickness)
Work done = Fmax * K * t -------------(i)
Where, K= % of penetration required to cause the
rupture
If shear is provided on punch or die, then
Punch travel=K*t + Amount of shear in cm = K*t + I
I= Total inclination or shear of punch in cm
Work done = F * (K*t + I) --------------------(ii)
Where, F, is actual force and it will be less the Fmax
Comparing equation (i) & (ii)
I =(Fmax -F) * K* t
F
F=Fmax * K * t

24. 2) Staggering of punch

25. 1) Drop through die

26. 2) Inverted type die

27. Factors which will influence the stock layout
1)Economy of material
2) Direction of material grains
3) Press used
4) Production required

28. 5) Spacing between blanks
Back or front scrap may be determined by the equation
a= t + 0.015*h
Feed, s= w + b
Number of blanks which can be produced from one
length of stock can be found as,
N= L-b
S

29. 1) Fixed strippers
Plate thickness
t = 1 (w/3 + 16t)
8

30. 2) Spring loaded Strippers

33. 1) Latch stop

34. 2) Automatic stop

35. Spherical type
B = A
C = 0.25 A
L = A to 2A
E = 0.625 A
Flat type
B = A
C = 0.625 A
L = 0.75 A
E = 0.5 A