What is EDM?

What is EDM? The EDM is stands for Electrical Discharge Machining or Electrical Discharge Machine. Other popular name for EDM is Electro Discharge Machine. There are two most popular EDM machine, Ram EDM Machine and EDM Wire Cut. Ram EDM also known as, Sinker EDM, Die Sinker, Vertical EDM or Plunge EDM. Ram EDM divided into two main categories, Conventional EDM and CNC EDM. EDM is a non conventional machining method to remove unwanted material from electrically conductive workpiece or metal. EDM is a machining method primarily used for hard metals, super-tough alloy, hardened materials or cutting delicate cavities that would be impossible to machine with conventional machining method such as milling, drilling, grinding or with other type of conventional machine tools. Some of the EDM applications are machining aerospace alloys such as titanium, inconel, & hastalloy, removing broken taps, drills, & bolts and machining of carbide dies and tools.


Conventional EDM or EDM Ram Type

How EDM works? Basically, the EDM process is simple the unwanted material removes by use of recurrent sparks applied to a hard metal. An electrical discharge is created between an electrode and the workpiece known as spark to create spark gap or spark erosion between the electrode and workpiece. For Ram EDM, a special brass will be fabricated into a desire shape and use it as an electrode. The brass will be attached to the EDM machine and use it to machine the workpiece under carefully controlled conditions. Read this blog post about Wire Cut EDM for more details information.


CNC Electrical Discharge Machine / CNC EDM

Photos by Creator Precision co., Ltd

During EDM process, the current will be switched on and off by moving the electrode up (current off) and down (current on) to control the spark gap. When the current is switched on the spark jumps across the gap and the small amount of unwanted material is removed from the workpiece to allow the electrode to be moved through the workpiece. The electrical spark are very short in duration, approximately 1 microsecond to 1 millisecond each. This process repeats its self over and over again until the electrode is slowly advanced deeper and deeper into the cut. The path of the electrode is typically controlled by a numerical controller (NC) for NC EDM machine or computer numerical controller (CNC) for CNC EDM machine, which allows a desire shapes to be produced.

The spark always takes place in the dielectric of deionized fluid which acts as a coolant and when the current is switch off the deionized fluid will flushes away the eroded particles from the workpiece. In fact, the electrode itself does not touch the workpiece being cut because the actual cutting is being done by the electrical discharge or spark created between the electrode and the workpiece.