ONA - EDM & ONA - Qué es EDM

Whats is EDM?

EDM is the technique used in industry for high-precision machining of all types of conductive materials (metals, alloys, graphite, ceramics, etc.), of any hardness.
	Part in tempered steel, machined using EDM

Definition

EDM is defined as the process of stripping off material using a successive series of electrical discharges at short intervals. These discharges jump between two poles (electrode - or working tool - and piece to be machined).

These discharges are created by electric pulse generators.

Physical principle of EDM
EDM machining is performed, therefore, by means of electric sparks which jump between two electrodes subjected to a given voltage which are submerged in an insulating liquid (dielectric fluid). Since the two electrodes are in a dielectric or insulating medium, the voltage applied to them must be sufficient to create an electric field which is greater than the dielectric rigidity of the fluid.


As a result of the action of this electrical field, free positive ions and electrons are accelerated, creating a discharge channel which becomes a conductor, and it is precisely at this point where the spark jumps. This causes collisions between the ions (+) and the electrons (-). A channel of plasma is thus formed.

These collisions create high temperatures in both poles and a ball of gas is formed around the plasma channel, which begins to grow. At the same time, the high temperatures in the two poles melt and vaporise part of the material of the part, while the electrode itself suffers only very slight wear.

In this situation (large ball of gas and molten material at both poles) the electric current is turned off. The plasma channel collapses and the spark disappears. The dielectric fluid then breaks the ball of gas making it implode (explode inwards). This creates forces which force the molten material ouy forming two craters on the surfaces. The molten material solidifies and is carried away in the form of balls by the dielectric fluid to form what we might call the "EDM splinter".