In the vast world of manufacturing, Electrical Discharge Machining (EDM) has become an indispensable machining method due to its unique process characteristics. Today, we're going to take a deep dive into this amazing process and learn how the energy of an electric spark can bring complex shapes and difficult-to-machine materials to life.

What is Electrical Discharge EDM?

Electrical Discharge EDM, also known as spark machining, spark erosion, or galvanic machining, is a process method that utilizes a pulsed electrical discharge to electrically etch conductive materials in order to remove excess material. This process removes material from a workpiece through a series of rapid cyclic current discharges between two electrodes, which are separated by a dielectric fluid and subjected to voltage. One electrode is called the tool electrode and the other is called the workpiece electrode.

Basic Principle

In the discharge EDM process, the tool and the workpiece are placed in a liquid medium with a certain insulating strength and are connected to the positive and negative terminals of a pulsed power supply. A regulating device controls the tool electrodes to ensure that a small discharge gap (typically 0.01-0.05 mm) is maintained between the tool and the workpiece for normal machining. When the strength of the electric field between the two electrodes is increased sufficiently, the liquid medium at the nearest point between the two electrodes is broken through, producing a short, high-energy spark discharge. The temperature in the discharge area can instantaneously reach tens of thousands of degrees Celsius, the metal is melted or vaporized, and the molten metal is thrown out and quickly washed away from the gap under the cooling of the liquid medium, thus forming a small crater on the surface of the workpiece. This process is repeated over and over again, with the tool electrode being fed into the workpiece, resulting in a machined surface made up of numerous small pits, with the shape of the tool being precisely reproduced on the workpiece.

Features of the process

1. Wide processing range: EDM can process any conductive hard-to-cut materials, such as hardened steel, heat-resistant alloys, cemented carbide, etc., which is difficult to realize by traditional cutting methods.
2. No cutting force: Since there is no direct contact between the tool electrode and the workpiece during the machining process, the cutting force is very small, which is especially suitable for machining complex shaped workpieces, low stiffness workpieces and microfabricated structures.
3. High precision: through precise control of discharge parameters, high precision machining can be realized to meet the needs of precision manufacturing.
4. Flexibility: the pulse parameters can be adjusted arbitrarily according to the needs, so the rough, fine and fine three-stage machining can be accomplished on the same machine tool, thus improving the machining efficiency.

Application fields

Discharge EDM is widely used in manufacturing industry, especially in the field of processing various complex cavities, punching molds and holes. It is not only capable of handling materials and shapes that are difficult to handle with conventional machining methods, but also plays an important role in the field of precision manufacturing. For example, discharge EDM plays an indispensable role in the fields of mold manufacturing, aerospace, automotive manufacturing, and electronics industry.