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Manufacturing Engineering
Machining Processes
GATE 2013
Medium

During the electrochemical machining (ECM) of iron (atomic weight=56, valency=2) at current of 1000 A with 90% current efficiency, the material removal rate was observed to be 0.26 gm/s. If Titanium (atomic weight=48, valency=3) is machined by the ECM process at the current of 2000 A with 90% current efficiency, the expected material removal rate in gm/s will be

  • A0.11
  • B0.23
  • 0.30
  • D0.52

Explanation

By Faraday's law, mass removal rate ∝ I·(Atomic Weight)/(valency) (efficiency η is the same 90% for both, so it cancels in the ratio). MRR_Ti = MRR_Fe × (I_Ti/I_Fe) × (A_Ti/A_Fe) × (z_Fe/z_Ti) = 0.26 × (2000/1000) × (48/56) × (2/3) = 0.26×2×0.8571×0.6667 ≈ 0.30 gm/s.

Source: GATE ME 2013 (Booklet Code A) (2013)

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