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GATE 2016 ME (ME3) – Question 59

Machining and Machine Tool Operations · Mechanics of machining · 2 marks · Multiple choice

For an orthogonal cutting operation, tool material is HSS, rake angle is 22°, chip thickness is 0.8 mm, speed is 48 m/min and feed is 0.4 mm/rev. The shear plane angle (in degrees) is

  1. 19.24
  2. 29.70
  3. 56.00
  4. 68.75

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Correct answer: (B) 29.70

Explanation

The uncut-to-cut chip thickness ratio is r=0.4/0.8=0.5. Geometry gives tanφ=r cosα/(1−r sinα), with α=22°. Thus φ=atan[0.5cos22°/(1−0.5sin22°)]≈**29.70°, B**. Cutting speed is unnecessary for this geometric relation.