It is mostly used for machining operations on hard metals and for complex operations, which are nearly difficult with outdated techniques.
What is Electrical Discharge Machining (EDM)?
- EDM is used to acquire the desired shape by means of electrical discharge operations. Material removal process has completed due to current discharge between two electrodes.
- In this operation dielectric liquid and electric voltage play very important role. As we know that electrical discharge machining operations come under non-conventional machining techniques.
Define EDM (Electrical Discharge Machining).
- The EDM process is removing unwanted material in the form of debris and produce shape of the tool surface as of a metal piece via an electrical expulsion trapped between tool and work piece i.e. (cathode and work piece) in presence of dielectric fluid.
- In these machining process tool is attached to negative so it called cathode (polarized electrical device) and work piece is called the anode, because, it is attached to positive. Dielectric fluids are kerosene, transformer oil, distilled water, may be filled.
1. Die-sinking EDM process
- This process was founded by two Russian scientists, B. R. Butinzky and N. I. Lazarenko in 1943 to find the ways of preventing the erosion of tungsten electrical contacts due to sparking.
- So many times, they were unsuccessful in this task but they found that the erosion was more precisely controlled if the electrodes were immersed in a dielectric fluid.
- This led them to invent an EDM machine used for working difficult-to-machine materials such as tungsten.
- In this process two electrodes are fitted on their places on the machine parts which is work bench and the tool holder. Both the electrodes must be the electrically conductive.
- After that both the electrodes are immersed in an insulating liquid dielectric with the help of the pump.
- The dielectric is the EDM oil/ kerosene / transformer oil. Then set the machining parameters on the CNC controller for machining on the work piece to get required shape and the size.
2. Wire EDM process
- The wire-cut kind of machine founded in the 1960s for the purpose of making tools (dies) from hardened steel.
- In this process the tool electrode in form of wire.
- To avoid the erosion of material from the wire causing it to break, the wire is wound between two spools so that the active part of the wire is constantly changing.
- The wire cut EDM process also called electric discharge wire cutting process.
- It is used for the producing two or three dimensional complex shapes using an electro-thermal mechanism for eroding the material from a thin single stranded by guide metal wire surrounded by deionised water which is used to the conduct electricity.