GATE 2018 ME (ME1) – Question 59
In orthogonal cutting, uncut thickness is 0.010 mm, cutting speed 130 m/min, rake angle 15° and width 6 mm. Chip thickness is 0.015 mm, cutting force 60 N and thrust 25 N. Friction-energy/total-energy ratio, to two decimals, is ______.
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Correct answer: 0.39 to 0.49
Explanation
Rake-face friction is $F=60\sin15^\circ+25\cos15^\circ=39.677$ N. Chip-speed ratio is $r=t_1/t_2=2/3$. Friction-power fraction is $Fr/F_c=39.677(2/3)/60=0.44086$, rounded to 0.44. Cutting speed cancels.