Electrical erosion cutting

Electrical discharge machining is a method of machining a part by changing its shape and size using electrical discharges generated between an electrode (the tool) and a conductive workpiece. Thus, one electrode is the workpiece itself, and the other is the electrode (the tool). To restore the electrical strength of the medium between the electrodes, periodic discharges, or pulsed discharges, are necessary.

To reduce electrode wear during electrical erosion cutting, unipolar pulses of process current are applied. Pulse duration affects polarity: with short pulses, anode erosion predominates, while with longer pulses, cathode erosion predominates. Both methods of applying unipolar pulses are used in this work.

Electrical erosion cutting involves several stages: first, electrical breakdown occurs, which can lead to spark discharges, followed by an arc discharge. Many generators are capable of producing a multi-stage pulse waveform.

The pulse frequency is determined by the technological requirements of the workpiece. The average pulse duration ranges from 0.1 to 10-7 seconds, and the frequency from 5 kHz to 0.5 MHz. The shorter the pulse duration, the cleaner the workpiece surface.

Electrical discharge cutting is a unique process because the free-form shape of the electrode tool allows for the processing of closed channels that are inaccessible by mechanical machining. This method can also be used to cut various conductive materials.

The disadvantage of this method is not very high productivity, very low feed rate (1 mm per min) and, of course, high energy consumption.

There are several types of electrical discharge cutting, some of them are:

• combined electrical erosion processing, which is combined with other types of processing simultaneously;
• electrical discharge chemical processing, which simultaneously involves electrochemical dissolution of the workpiece in an electrolyte.
• Electrical discharge machining involves the use of electrical discharge machining to destroy metal;
• anodic mechanical treatment;
• Volume copying is an electrical discharge machining (EDM) that displays the shape of the surface of the electrode-tool on the electrode-workpiece.