Electrical Discharge Machining – The Basics

Electrical Discharge Machining (EDM) has also become known as spark machining, spark erosion, wire machining and wire erosion. It is a very useful manufacturing process used to produce otherwise impossible to manufacture, complex or intricate shapes and finished parts in soft or hard alloys.

EDM works by utilising a ‘pulse generator’ (see Diagram) to produce – in a very precisely controlled manner – ‘pulses,’ or discharges of electrical energy.


Hundreds of thousands of discharges are emitted between the electrode and the workpiece every second. As the discharges impact the workpiece at 5000°C they vaporise the metal, the molten pool being ejected by the implosion of gasses. The resulting swarf generated through the process is spectacular when seen at microscopic level.

As the discharges of energy are precisely controlled, the faithful reproduction of any shape can be achieved – providing, of course, that the electrode itself can be produced.

In the process of wire erosion, the electrode is the wire travelling under tension through the workpiece which is moved under CNC control. Accuracies of 5 to 40 microns can be achieved.

Electrical Discharge Machining is used in a huge variety of applications. EDM is becoming a popular method of making prototypes and production parts, in a range of industries from automotive and aerospace to electronics and surgical. Production quantities large or small are achievable. Oil/gas exploration industries provide our biggest customer base.

Erodatools have been specialists in EDM and spark erosion for more than 42 years. We have a skilled team who can provide services to customers throughout the UK and overseas, and a huge range of modern EDM machines as well as load handling facilities to ensure that no job is too big for us. For any further information about what EDM is, or what it can be used for – simply give us a call today. We’ll be happy to discuss your project and recommend the ideal solution!