GATE 2018 ME (ME1) – Question 65

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

ECM cuts a 10 mm × 30 mm rectangular through-hole in a 12 mm aluminium plate in 2 minutes at 90% efficiency. Aluminium specific removal rate is $3.44\times10^{-2}$ mm³/(A s). Required current, to two decimals, is ______ A.

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Correct answer: 968.80 to 969.20

Explanation

Removed volume is $10(30)(12)=3600$ mm³ over 120 s. Effective removal rate is $0.9(0.0344)I$. Therefore $I=3600/(120\times0.9\times0.0344)=968.99$ A.