
365Machining by Electrochemical Erosion
11.5 Solved Example
It is required to drill a hole of 10 mm diameter and 20 mm depth in a hard
alloy using the following conditions:
Tool feed rate 2 mm/min Faraday’s constant 96,500 A s
Gap voltage 20 V Electrolyte conductivity 0.032 Ω
−1
mm
−1
Voltage drop 0 V Density of workpiece 0.0084 g/mm
3
Atomic weight 42.44 Oversize (diametral) 2 mm
Current efciency 100% Valence 2
Calculate the following:
a. Machining time
b. Tool diameter
c. Machining current
d. Machining gap
Solution
a. The machining time for the hole depth l and feed rate a
t
m
== =
10 min
b. The tool diameter (d
t
) is calculated from the wor