Question

In a single pass drilling operation, a through hole of $15$ mm diameter is to be drilled in a steel plate of $50$ mm thickness. Drill spindle speed is $500$ rpm, feed is $0.2$ mm/rev and drill point angle is ${118}^o$. Assuming $2$ mm clearance at approach and exit, the total drill time (in seconds) is

• A. $35.1$
• B. $32.4$
• C. $31.2$
• D. $30.1$

Answer 1

The correct option is A $35.1$

$\text{Drilling time}=\frac{\text{Distance covered}}{\text{Speed}}$

$\text{Drilling time}=\frac{50+2\times 2+4.5}{0.2\times \frac{500}{60}}=35.1sec$