Question

At what rpm should a lathe be run to give a cutting speed of 20 m/min when turning a rod of diameter 40 mm?
1. 100 rpm
2. 160 rpm
3. 200 rpm
4. 250rpm

Answer 1

Correct Answer - Option 2 : 160 rpm

Concept:

Cutting speed is given by

V = πDN

Where V = cutting speed, D = diameter, N = speed in RPM

Calculation:

Given:

V = 20 m/min , D = 40 mm = 0.04 m

V = πDN

20 = π × 0.04 × N

N = 160 rpm