Graphite Electrode

In the metal processing industry, metal electrical processing methods are divided into two categories: electric thermal methods based on current heat effects and electrochemical methods based on current chemical effects. Electrical discharge machining is a kind of electrical thermal method.

Electrical discharge machining (EDM) is also known as electrical spark discharge machining. Its principle is to take advantage of the electrocorrosion phenomenon between the graphite electrode for EDM and the workpiece during pulse spark discharge, to remove excess metal and meet the machining requirements of corresponding parts on size, shape, and surface quality.

Graphite electrode for EDM can not only machine general materials workpieces, but also various metal materials with high melting point, high hardness, high toughness and workpieces with high precision requirements that are difficult to machine by using traditional cutting methods. Therefore, graphite electrodes for EDM are especially suitable for machining mold parts.

High electrical resistivity. The electrical resistivity of graphite electrodes is tens to hundreds of times greater than that of metal materials like copper, and exhibits obvious anisotropy.
Good mechanical strength. Compared with other materials, the mechanical strength of graphite electrodes (tensile strength, compressive strength and bending strength) increases as temperature rises.
High thermal conductivity. The thermal conductivity of graphite electrodes is relatively high, being approximately half that of brass and similar to that of aluminum. It is approximately 91.96–137.94 W/(m·K).
Low coefficient of linear expansion. The linear expansion coefficient of graphite is smaller than that of metal materials, and it has good resistance to thermal shock. The unidirectional coefficient of linear expansion is about 2.0 × 10-6 to 2.0 × 10-6 °C-1.
High purity. Generally, the purity of artificial graphite electrodes for electrical processing is above 99%.