Question:-
A mild steel plate 400mm x 800mm x 30mm is to be shaped along its wider face. The ratio of return time to cutting time is 2 : 3 and the feed per cycle is 2mm. tool approach and over-travel respectively are 50mm latch cutting speed of tool is 24m/min. calculate the machining time required for machining the given plate with H.S.S. tool :
Option (A)
5 min
Option (B)
20 min
Option(C)
13 min
Option(D)
17 min
Correct Option:
(C)
Question Solution:
Length of the stroke
L = 800 + 50 + 50 = 900mm = 0.9m
Cutting stroke time = 0.9/24 = 0.0375min
(Return time/cutting time) = 2/3
Return time = (2/3) x cutting time
= (2/3) x 0.0375 = 0.025
Total time per cycle = 0.0375 + 0.025 = 0.0625
Shaping width B = 400 + (2 x 5) = 410 mm
Number of cycle required = (410/2) = 205 cycle
Total machining time 205 x 0.0625 = 13 min (say)
question-answer-faq-8990