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Electrical discharge milling

Machining method which controlled spark discharges from an electrically charged and rotating electrode milling workpiece surface.

Beskrivning
Illustration of Electrical discharge milling

The process

The tool consists of a roller [1], which rotates about its vertical axis.

Connection via power supply makes the wheel acts as the cathode and workpiece as the anode. When the electrode is brought close to the workpiece, intermittent spark discharges occur, which means that the workpiece is melted and vaporized.

The discharge is supported by a dielectric liquid [2], which in combination with the rotation of the roller helps to cool the process and carry away the removed material while the roller is moved through the workpiece. The spark gap [3] makes the machined surface slightly separate from the outer diameter of the roller.

It is important that the electrode, i.e., the roller is electrically conductive and it’s normally made of metal or graphite.

Synonyms

Electrical Discharge Milling
Electrical discharge milling
Process films
Advantages and disadvantages
In comparison with alternative methods
Can process complex forms
Tight tolerances
No cutting forces, so small workpieces can be produced safely
Good surface finish
Very fine holes can be created
extremely hard materials can be processed
Slow material removal rate
Additional time and cost of electrodes
Precision of sharp edges a challenge