Question

A blank of $50mm$ diameter is to be sheared from a sheet of $2.5mm$ thickness. The required radial clearance between the die and the punch is $6\%$ of sheet thickness. The punch and die diameter $\left(mm\right)$ for this blanking operation respectively are

• A. $50.00\text{and}50.30$
• B. $50.00\text{and}50.315$
• C. $49.70\text{and}50.00$
• D. $49.85\text{and}50.00$

Answer 1

The correct option is C $49.70\text{and}50.00$

$\text{Radial clearance}=\frac{6}{100}\times t$
$\Rightarrow \frac{6}{100}\times 2.5=0.15mm>0.1$
Total clearance $=2\times 0.15=0.3$ mm
Dia of die = Dia of blank = $50$ mm
Dia of punch = Dia of die - clearance
$=50-0.30=49.70\text{mm}$