For this procedure it is characteristic that the material erosion develops through a sequence of electrical discharges.

An discharge is a compensation between positive and negative charges, workpiece and wire have different polarity (+/-).

As consequence of an discharge a spark skips between two poles. These discharges are local and temporally from each other separated, which meant that in each case a spark develops, he does at a certain time and a certain place. This process occurs sequentially with a very high rate (frequency). The spark moves figurativy seen over the workpiece. Discharges are caused by voltage supplies about over 20 V. The handling takes place in a handling liquid, which is electrically not conductive, that means, in an water filled basins. In the machine the electrical conductivity is extracted from the water by a chemical process. The spark erosion is well-known also under the name electrical discharge or the English designation EDM (Electrical Discharge Maschining).

Phase 1 If a discharge (spark branch) develops, a high voltage must be available. This voltage is dependent on: the distance between electrode (wire) and workpiece the conductivity (isolation) of the handling liquid the degree of pollution of the handling liquid

Phase 2 At the point with the strongest " electrical field ", which meant the largest difference of potential between positive and negative charge, the discharge will be released (spark branch).

Phase 3 Under effect of the electrical field the positive and negative particles approach one on the other. This occurs with an extreme acceleration, whereby the speed of the particles becomes ever higher. Within shortest time a conductive channel develops between both poles (workpiece/wire), which bridges the handling liquid.

Phase 4 In this stage the current flows and the spark skips. Temperatures between 8000 C and 12000 C develops. The result of the high temperatures is a plasma zone of melted material. Because of material-particles and the continuous electrical impulse the plasma zone spreads and further material at the workpiece and at the electrode is melted. At the same time a gas-bubble develops from the steam formation at workpiece and wire and from the evaporation of the handling liquid, The pressure of the bubble rises constantly and becomes very high.

Phase 5 During the interruption of circuit the temperature sinks abruptly and causes a implosion of the gas bubble. By the freed forces of the Implosion the melted material is thrown out of the developed crater.

Phase 6 The melted material becomes again fixed in the cool handling liquid. In the shape of small balls (metal-dust) it is now filtered out of the handling liquid. The erosion on the workpiece is asymmetrical. It depends on the heat conductivity, the material fusing point and the duration and the intensity of discharges. This unbalance lies within ranges from a few 1/1000 mm.

In the year 1770 the English scientist Priestley discovered the eroding effect of electrical discharges.

During the investigation for the suppression of the erosion at electrical contacts the Soviet scientists B. R. Lazarenko and N. I. Lazarenko had an idea to use the destructive effect of an electrical charge to the development of a controlled metalworking procedure.

In 1943 they developed a working-procedure with spark erosion, at which a electrical discharge between two conductors dipped in a dielectric liquid takes place.

The principle of the unloading generator (with the designation Lazarenko set), applied at that time, was used long time for the building of generators for erosion-machines.

This type of generator is used until today in improved execution for some applications.

The impressive advancement of the spark erosion is to be owed by the eagerness of different scientists, who works for the improvement of the procedure and their optimal use in the today's time.