How does EDM machining works

What is EDM?

Electrical discharge machining (EDM) is a manufacturing process in which sparks are generated by electric discharge to make a work piece into a desired shape. The dielectric liquid separates the two electrodes and applies a voltage to produce a periodic and rapid current discharge to remove the material. One of the electrodes is called the tool-electrode, or simply the tool or electrode, while the other is called the workpiece-electrode, or work piece. There is no actual contact between the tool electrode and the work piece electrode during the EDM machining.

When the voltage between the two electrodes is increased,  the electric field between the two electrodes will also increase. Causing dielectric break down of the liquid, and produces an electric arc. As a result, material is removed from the electrodes. Once the current stops, the new dielectric will flow into the electric field between the electrodes. enabling the solid particles (debris) to be carried away. And the dielectric insulating properties will be restored. After a current flow, the voltage between the electrodes is restored to what it was before the breakdown, so that a new liquid dielectric breakdown can occur to repeat the cycle.


The EDM process is widely used in the mold manufacturing, tool, die mould industries, while it is becoming a common method of making prototype and small scale production, especially in the aerospace, automobile and electronics industries in which production quantities are relatively low. In sinker EDM, a graphite, copper tungsten, or pure copper electrode is machined into the desired (negative) shape and fed into the work piece on the end of a vertical ram.
EDM can be used to process super hard materials and complex-shaped work pieces that are difficult to process by traditional cutting methods. It is usually used to process conductive materials. It can process with complex cavities or contours structure on difficult-to-process materials, such as titanium alloys , tool steels , carbon steels , and cemented carbides.
The machine tools that apply this processing method mainly include:
Electrical discharge forming machine tool: The tool electrode is generally graphite or copper. The tool and the work piece are immersed in a kerosene-based working fluid, and the shape of the tool electrode is copied to the work piece by electric discharge.
Discharge wire cutting machine: the use of deionized water as the insulating medium, using brass or galvanized brass wire as a tool electrode wire (Chinese invention reciprocally traveling wire EDM cutting machine usually emulsion using Molybdenum wire as tool electrode).

Precision CNC Machining

Sinker EDM

Sinker EDM Machining

Sinker EDM, also called ram EDM, cavity type EDM,die sinking, traditional EDM or volume EDM.
Using Sinker EDM, allows to machine and produce complex geometry shapes. often with small or odd shaped angles. Vertical, orbital, vectorial, directional, helical, conical, and rotational also used.
This method requires electrodes (often made from graphite or copper) that are pre-machined to have the necessary shape. This electrode is then sunk into the work piece, creating the negative version of its original shape.

Wire EDM


Wire EDM and is also known as wire-cut EDM and wire cutting. In Wire EDM a thin wire is used to cut the work piece. In this case, the wire is the electrode. During the machining, the wire is constantly coming from an automated feed with a spool. If the cut has to be made in the middle rather than the outside of the work piece, small hole drilling EDM is used to make a hole in the work piece through which the wire is threaded afterwards.
The wire is held with diamond guides. Usually the liquid is deionized water. The wire is often made from brass or copper.

Hole Drilling EDM

Hole drilling EDM mainly for machining fast, accurate, small and deep holes. It is conceptually akin to sinker EDM but the electrode is a rotating tube conveying a pressurized jet of dielectric fluid. It can make a hole an inch deep in about a minute and is a good way to machine holes in materials too hard for twist-drill machining. This EDM drilling type is used in the aerospace industry, producing cooling holes into Aero blades and other components. It is also used to drill holes in industrial gas turbine blades, molds, and bearings. In Addition, hole drilling EDM doesn’t need any deburring.



Machined odd-shaped

It can produce odd-shaped and different surfaces that cannot be produced by traditional cutting machines.

Machined hard materials

Machining of extremely hard material with high accuracy.Sharp corner processing inside containers and pipes

Machined Small Parts

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Without Perceivable Distortion

There is no direct contact between tool and work piece. Therefore, delicate sections and weak materials can be machined without perceivable distortion

Very Good Surface

A very good surface may be obtained by redundant finishing paths.

Machined Small and Deep Hole

Very fine holes can be attained, small and deep hole machining, diameter up to 0.015″

EDM Machining Shop2
EDM Machining Shop3

As a experienced manufacturing in China, DDPROTOTYPE can provide customers with precise EDM Machining services with our advanced EDM equipment. No matter how complicated the structure is, we always have a suitable solution to achieve it.