GATE 2018 ME (ME2) – Question 62

Machining and Machine Tool Operations · Abrasive and non-traditional machining processes · 2 marks · Numerical answer

EDM machines a circular hole of diameter 25 mm and depth 20 mm. Material removal rate (mm³/min) is $4\times10^4IT^{-1.23}$, with I = 300 A and material melting point T = 1600°C. Find machining time (min), to two decimal places.

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Correct answer: 7.00 to 7.30

Explanation

Hole volume is $V=\pi(25)^2(20)/4=9817.477$ mm³. The empirical removal rate is $4\times10^4(300)(1600)^{-1.23}=1374.401$ mm³/min. Thus machining time $V/\mathrm{MRR}=$ **7.14 min**. Use the specified Celsius value in this empirical formula.