434 Sam Green Road, Greenhill Industrial Park, Tunney Ext 6, Germiston 011 828 7828

Electrical Discharge machine

What is an electrical discharge machine? (Also know as a spark eroder)

Electrical Discharge Machining (EDM) is a controlled metal-removal process that is used to remove metal by means of electric spark erosion. In this process an electric spark is used as the cutting tool to erode the workpiece to produce the finished part to the desired shape. The metal-removal process is performed by applying a pulsating On-Off electrical charge of high-frequency current through the electrode to the workpiece. This removes (erodes) very tiny pieces of metal from the workpiece at a controlled rate.

Eroding Process

EDM spark erosion is the same as having an electrical short that burns a small hole in a piece of metal it contacts. With the EDM process both the workpiece material and the electrode material must be conductors of electricity.

What is an electrode?

An electrode is usually made from graphite or copper, which is shaped to the form of the cavity it is to reproduce. The formed electrode is fed vertically down, and the reverse shape of the electrode is eroded into the solid workpiece.

Conventional EDM

In the EDM process an electric spark is used to cut the workpiece, which takes the shape opposite to that of the cutting tool or electrode. The electrode and the workpiece are both submerged in a dielectric fluid, which is generally light lubricating oil. A servomechanism maintains a space of about the thickness of a human hair between the electrode and the work, preventing them from contacting each other.

What is Flushing?

One of the most important factors in a successful EDM operation is the removal of the metal particles from the working gap. Flushing these particles out of the gap between the workpiece to prevent them from forming bridges that cause short circuits. Too much fluid pressure will remove the particles before they can assist in the cutting action, resulting in slower metal removal. Too little pressure will not remove the particles quickly enough and may result in short-circuiting the erosion process.

Advantages of EDM machines

Conventional EDM machines can be programmed for vertical sparking, orbital, vectorial, directional, helical, conical, rotational, spin and indexing sparking cycles. This versatility gives Electrical Discharge Machines many advantages over conventional machine tools.
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