Page 171 - Module DMV20173

Describe some advantages of electrical-discharge machining.

With increasing strength and toughness and various other properties of advanced
engineering materials, there was a need to develop processes that were not sensitive

to these properties.

Because EDM basically involves electrical properties and is capable of removing
material in a variety of configurations, it was one of the most important developments
and continues to do so. As in all other processes, it has its advantages as well as

limitations, regarding particularly the material-removal rate and possible surface
damage which could significantly reduce fatigue life.

EXERCISE 8.2

A wire EDM operation is used to cut out die components from 25 mm thick tool steel
plates. However, initial cut give the poor surface finish on the cut edge. What
changes in discharge current and frequency of discharges should be made to
improve the finish?

 Increased Current.
 Increased Frequency.

EXERCISE 8.3

Describe two (2) advantages to use of Laser Beam Machining as compared to
conventional machining.

i. The laser beam is easy to manipulate with computer-controlled machinery,
allowing intricate patterns to be easily programmed.
ii. The laser beam can be focused precisely and it restricts material removal to

sub millimetre depth.
iii. The marking process does not require hard tooling, or any preparation and
subsequent cleaning.
iv. Since marking only requires a very shallow depth of cut, low-powered lasers
are capable of marking most materials, making this approach very cost-

effective.