Electric Discharge Machining (EDM)

What does EDM stand for?

Electric Discharge Machining.

What energy category does EDM belong to?

Thermal energy processes.

How does EDM remove material?

Repeated electrical sparks create localized temperatures that melt or vaporize small amounts of metal.

What material restriction applies to EDM?

The workpiece must be electrically conductive.

How is the finished cavity shape produced in EDM?

By a formed electrode tool.

Where do EDM sparks occur?

Across a small gap where the tool and work surfaces are closest.

Why is dielectric fluid required in EDM?

It ionizes to create a discharge path, flushes debris, and removes heat.

How frequently do EDM discharges occur?

Hundreds or thousands of times per second.

What two parameters strongly affect EDM performance?

Discharge current and discharge frequency.

How does increasing current or frequency affect EDM material removal rate?

It increases the material removal rate.

What EDM settings provide the best surface finish?

High discharge frequency and low discharge current.

What is overcut in EDM?

The distance by which the machined cavity exceeds the tool size on each side.

Why does EDM overcut occur?

Because sparks occur along the sides of the tool as well as the front.

What electrode materials are used in EDM?

Graphite, copper, brass, and other conductive materials.

Why is graphite often preferred for EDM electrodes?

It vaporizes at very high temperatures and usually gives a high (work removal to tool wear) ratio.