An electrical discharge machine, or EDM, is understood to be spark eroding, burning, spark machining, wire burning, and die sinking equipment. The machine is used to manufacture desired shapes in materials through the use of electrical discharges or sparks. The discharge is achieved through two electrodes – the tool electrode and the workpiece electrode – which are separated by a dielectric liquid subject to the electric voltage. The lesser the distance between the two electrodes, the greater the electric discharge. Therefore, material is removed from the electrodes and flushed with the introduction of dielectric liquid.
There are two main types of EDM: wire EDM and sinker EDM. For the purposes of this article, we will be exploring sinker EDM
Sinker EDM: The Process
Sinker EDM is also known as volume EDM, die sinking EDM, or cavity EDM. For this process, a work table specifically designed for the process is used. The work table is made airtight so that it can hold a sinking bath, which is usually made up of kerosene, distilled water, or deionized water. The workpiece and an electrode are submerged into that insulating fluid and then connected with a specific supply of power, which creates electrical potential between the two components. When the electrode reaches the workpiece, the dielectric discharge is released and forms a plasma channel with slight sparks.
Applications of Volume EDM
Sinker EDM is generally used when the material being machined requires a high tolerance or corner radius. It can be used for the production of molds and dies and is perfect for the tooling industry because it creates molds with smooth finishes and can cut intricate shapes.
Advantages of Cavity EDM
The sinker EDM process provides high-quality finishes and durable results. Although it can have excessive power consumption and slow material removal processes, it has a number of advantages, including the ability to cut tough or exotic materials, cuts thin materials by preventing any damages, and, once the part is cut, little or no polishing is required. The last advantage is due to the fact that the process takes place in a fluid – this also contributes to improved cooling and fast discharge.