Question

The surface irregularities of electrodes used in an electrochemical machining (ECM) process are 3 $\mu$m and 6 $\mu$m as shown in the figure. If the work-piece is of pure iron and 12V DC is applied between the electrodes, the largest feed rate is_____mm/min

Conductivity of the electrolyte	0.02 $oh{m}^{-1}m{m}^{-1}$
Over-potential voltage	1.5 V
Density of iron	7860 $kg/m^3$
Atomic weight of iron	55.85 gm

Assume the iron to be dissolved as $F{e}^{+2}$ and the Faraday constant to be 96500 Coulomb.

• A. 51.542

Answer 1

The correct option is A 51.542

$R=\frac{\rho L}{Area}=\frac{\frac{1}{0.02}\times 0.009}{Area}=\frac{50\times 0.009}{Area}$

$I=\frac{V}{R}=\frac{(12-1.5)\times Area}{50\times 0.009}$

$=23.33\times Area$

$L=3+6=9\mu m=0.009mm$

$MRR=\frac{AI}{\rho ZF}=\frac{55.85\times 23.33\times Area}{7860\times {10}^{-6}\times 2\times 96500}$

$\frac{MRR}{Area}=0.8590mm/s=51.542mm/min$