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GATE 2019 ME (ME1) – Question 25

Machining and Machine Tool Operations · Machining operations, machine tools, cutting tools and tool geometry · 1 mark · Multiple choice

A 400 mm × 40 mm × 20 mm steel sample is reduced uniformly in thickness by 2 mm in one pass using horizontal slab milling. Cutter diameter is 100 mm, width 50 mm, with 20 teeth, rotating at 1200 rpm. Feed per tooth is 0.05 mm, along sample length. Overtravel equals approach distance. Find approach and total machining time.

  1. 14 mm, 18.4 s
  2. 21 mm, 28.9 s
  3. 21 mm, 39.4 s
  4. 14 mm, 21.4 s

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Correct answer: (D) 14 mm, 21.4 s

Explanation

Approach distance is $a=\sqrt{d(D-d)}=\sqrt{2(98)}=14$ mm. Feed rate is $0.05(20)(1200)=1200$ mm/min. Total travel is $400+2(14)=428$ mm, giving $428(60)/1200=21.4$ s. **D**.