Correct Answer - Option 1 : 1.31 min
Concept:
Time for machining \(= \frac{L}{{f.N}}\)
where L is job length (mm), f is feed (mm/rev), N is job speed (rpm)
Calculation:
Given:
Cutting speed = 478 rpm, f = 0.8 mm/rev, L = 500 mm, D = 40 mm, V = 60 m/min
Time for machining \(= \frac{L}{{f.N}} = \frac{{500}}{{0.8 × 478}} = 1.31\;min\)