Answer:
24.616 mm
12.384 mm
Explanation:
[tex]D_b[/tex] = Blanking die diameter = 25 mm
[tex]D_h[/tex] = Punch diameter = 12 mm
a = Allowance = 0.06 for aluminium
t = Thickness = 3.2 mm
Clearance
[tex]c=at\\\Rightarrow c=0.06\times 3.2\\\Rightarrow c=0.192[/tex]
Diameter of punch is
[tex]d_p=D_b-2c\\\Rightarrow d_p=25-2\times 0.192\\\Rightarrow d_p=24.616\ mm[/tex]
Diameter of blanking punch is 24.616 m
For punching operation
[tex]d_d=D_h+2c\\\Rightarrow d_d=12+2\times 0.192\\\Rightarrow d_d=12.384\ mm[/tex]
The diameter of punching die is 12.384 mm