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GATE 2016 ME (ME2) – Question 62

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

Electrode surface irregularities in ECM are 3 μm and 6 μm as shown. Pure iron is machined at 12 V DC. Electrolyte conductivity is 0.02 Ω⁻¹mm⁻¹; over-potential is 1.5 V; iron density is 7860 kg/m³; atomic weight is 55.85 g/mol. Iron dissolves as Fe²⁺; Faraday constant is 96500 C/mol. The largest feed rate is ______ mm/min.

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Correct answer: 51.0 to 52.0

Explanation

The limiting nominal gap is the sum of the two peak irregularities:6+3=9µm=0.009mm. Effective voltage is12−1.5=10.5V. Faraday dissolution speed is κV M/(nFρg), using κ0.02, M55.85g/mol, n2, F96500 and density0.00786g/mm³. Multiplying the resulting mm/s by60 gives **51.543mm/min**.