Correct option is B
Given:
· Cutting speed (V) = 30 m/min,
· Diameter (D) = 60 mm.
Rearrange the formula to solve for rpm:
Rpm = (V × 1000)/(π×D)
Substitute the values:
Rpm = (30 × 1000)/(π×60)
Rpm = 30,000/188.5 ≈ 159.15
Thus, the recommended rpm for plain turning a 60 mm diameter workpiece at a cutting speed of 30 m/min is 159 rpm.
