Question

A $600mm\times 30mm$ flat surface of a plate is to be finish machined on a shaper. The plate has been fixed with the $600mm$ side along the tool travel direction. If the tool over-travel at each end of the plate is $20mm$, average cutting speed is $8m/min$, feed rate is $0.3mm/stroke$ and the ratio of return time to cutting time of the tool is $1:2$, the time required for machining will be

• A. $8min$
• B. $12min$
• C. $16min$
• D. $20min$

Answer 1

The correct option is B $12min$

Length travellent in forward stroke

$=600+20+20=640mm$

$\text{Total strokes}=\frac{30}{0.3}=100$

$\text{Total trand}=640\times 100$

$=64000mm=64m$

$\text{Time of storkes}=\frac{64}{8}=8min$

$\text{Return time}=\frac{cuttingtime}{2}=\frac{8}{2}=4min$

$\text{Total time}=8+4min=12min$