Question

A blanking operation is to be performed on 2.0 mm thick cold rolled steel (half hard). The part is circular with diameter = 75.0 mm. Determine the appropriate punch and die sizes for this operation.

Answer 1

Answer:

The punch size is 74.70 mm

The die size is 75 mm

Explanation:

From the table of allowance, the allowance for cold rolled steel ($A_c$) is given as 0.075.

Given that: thickness = 2.00 mm, blank diameter ($D_b$)= 75.0 mm

The clearance (c) is the product of allowance and the thickness of the cold rolled steel. It is given by:

$c=thickness*A_c=2\ mm(0.075)=0.15\ mm$

The die diameter is equal to the blank diameter and the punch diameter is smaller than the blank diameter by twice the clearance

Punch diameter = $D_b-2c=75\ mm-2(0.15)=75\ mm-0.3\ mm = 74.70\ mm$

Die diameter = $D_b=75\ mm$

the appropriate punch diameter is 74.70 mm and die size is 75 mm