GATE 2017 ME (ME2) – Question 65
In orthogonal machining with rake angle 9°, uncut chip thickness is 0.2 mm and chip thickness varies between 0.25 and 0.4 mm. The ratio of maximum to minimum shear angle is ______.
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Correct answer: 1.45 to 1.53
Explanation
Chip ratio r=t1/t2 ranges from0.2/0.4=0.5 to0.2/0.25=0.8. Use tanφ=r cosα/(1−r sinα) with rakeα=9°. This gives minimumφ≈28.18° and maximumφ≈42.09°, so their ratio is **1.493**, within1.45–1.53. Take the ratio of angles, not of their tangents.