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Electrical / Chemical

Molding and Tooling

The HK Series EDM graphite was developed based on the technology nurtured through our operations as a world-class supplier of carbon and graphite products since the firm's establishment in 1918. Today, HK series EDM graphite has flourished into a widely recognized quality brand not only in Japan but also in the world market. Tokai Carbon is continuing to develop materials to enhance its reputation as a global brand of EDM graphite.

Comparison of Graphite and Copper Electrodes

General Characteristics

*1 RT to 100°C  *2 Vaporization point

Specifications Graphite Copper
Specific Gravity 1.7-1.9 8.9
Coefficient of Thermal Expansion (×10-6/°C) *1 3.0-6.0 16.7
Melting Point (°C) 3600 *2 1083
Specific Resistance (μΩm) 10-25 0.02

Compared with copper, graphite is lighter with a smaller coefficient of thermal expansion, therefore, smaller thermal deformation.

EDM Characteristics

When IP is 20A or smaller, you do not notice much difference in EDMing speed between graphite and copper electrode wear can be some what lower for copper electrodes.

However, as IP increases, graphite electrodes will show much faster EDMing speed, while also showing reducations in electrode were. With copper electrodes, on the other hand, you will experience slower EDMing speed and higher electrode were when IP increases.

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Changes in Electrode Were and EDMing Speed

The above chart shows the change in electrode were and EDMing speed plotted against the on time for each grade of graphite in the HK Series. Note that the changes obtained by HK-0 are used as the standard score of 100. You can see that the HK grades with smaller average grain size show higher EDMing speed.

It is recommendable to use smaller grain size grades precision finishing, while using larger grain size grades for rough finishing where EDMing speed is critical.

Carbon Brash

Refined through years of experience, Tokai's high quality brushes are suitable for diverse applications. Our brushes are high quality both in rectifying capacity and high speed resistivity. With a solid reputation among our customers, our brushes are used for traction motors and electric motors.

Anti-Corrosion Materials

Tokai Impervious Graphite is a material used in the Chemical Industry for the construction of Heat Exchangers, Condensers etc. The Graphite is made impermeable by impregnation with a special synthetic resin. In particular, heat exchangers are the most popular application because of the advantageous thermal properties.

Glassy Carbon is a unique material, which features gas and liquid impermeability and excellent anti-corrosion to acids, alkalis, salt and organic chemicals. Glassy carbon is widely used for jigs in the wet cleaning process of Silicon wafers.

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