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GATE 2016 ME (ME1) – Question 60

Machining and Machine Tool Operations · Cutting tool materials, tool life and wear, economics of machining · 2 marks · Multiple choice

The HSS tool-life equation is $VT^{0.14}f^{0.7}d^{0.4}=\text{constant}$. A 30 min tool life is obtained at V = 45 m/min, f = 0.35 mm and d = 2.0 mm. If speed, feed and depth of cut are increased individually by 25%, the tool life is ______ min.

  1. 0.15
  2. 1.06
  3. 22.50
  4. 30.0

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Correct answer: (B) 1.06

Explanation

The equation is VT^0.14 f^0.7 d^0.4=constant. Increasing each of V,f,d by25% gives(Tnew/30)^0.14=1/(1.25^(1+0.7+0.4)). Therefore Tnew=30/1.25^(2.1/0.14)=1.0555min, matching **1.06min, B**. The keyed interpretation increases all three parameters together.