
F=
A x Tß
F = Cutting force
S = Material thickness
L = Total cutting length
A = L x S = Shear area
Tß = Shear strength
Note : Shear strength = 80% of tensile strength


P=
( L x S x Tß ) / 10
P = Stripping force
S
= Material thickness
L = Total cutting length
A = L x S = Shear area
Tß = Shear strength


L
= a + ( R + q x s/2 )( Pi x ° / 180)
L = Flat blank length
a, b = Length of legs
R = Bend radius
q = Correction factor ( refer to table below )
° = Bend angle
Pi = 3.1416


Correction
factor q

Ratio
R : s 
5.0 
3.0 
2.0 
1.2 
0.8 
0.5 
Correction
factor 
1.0 
0.9 
0.8 
0.7 
0.6 
0.5 
R = Bend radius
S
= Material thickness


E
= ( D + s ) 0.707
C = ( D + s ) 1.414
E = Center distance
C = Center distance between two apart radii
s = Material thickness
D = Inside diameter of final formed part
R = D/2 ( approximate )
Note : if R = D/2, radii will be tangent, if R /= D/2,
radii will require blending.


Thickness
S

1st
Draw

2nd
Draw

Sizing
Draw

<
0.4

1.08
S

1.091.10
S

1.041.05
S

0.4
 1.27

1.08
 1.10 S

1.10
 1.13 S

1.05
 1.06 S

1.27
 3.18

1.10
 1.13 S

1.13
 1.15 S

1.06
 1.08 S

>
3.175

1.13
 1.15 S

1.15
 1.20 S

1.08
 1.10 S

S = Material thickness

Draw
reduction
( number of draw )

H
/ D

No.
of draw

<
0.75

1

0.7
 1.5

2

1.5
 3.0

3

3.0
 4.7

4

H
= Draw piece height
D = Mean diameter of draw piece


%
= 1 ( MD / D )
%
= percentage of reduction
MD = Mean diameter of draw piece
D = Flat blank diameter


A
= 0.7854 (( DXD )(dXd))
D
= Flat blank diameter
d = Hole diameter


A
= 3.1416 ( D x H )
D
= Mean diameter
H = Shell height


A=
4.935 RD + 6.283 (R x R)
D = Hole diameter
R = Radius ( 1/2 thickness )


A=
4.935 RD  6.283 (R x R)
D = Outer diameter
R = Radius ( 1/2 thickness )


A=
6.283 ( R x R )
R = Radius ( 1/2 thickness )


A
= 6.283 RH
R
= Radius ( 1/2 thickness )
H = Shell height


A
= 9.87 RD
D = center to center diameter
R = Radius ( 1/2 thickness )




Online
formula






