4. Manufacturing Process

1.Pulverizing

Raw materials such as coke are pulverized.
2. Kneading & Pulverizing/Mixing

Bonding material called binder is added to the pulverized coke, and mixed while heating. After cooling, materials in the form of pebble are gained, which is to be pulverized again.
3. Isostatic Pressing (CIP)

The powder is put into the rubber container, which is fit in the metal frame. And it is molded by applying the equal pressure in the water. If pressure is applied from the top and bottom only, graphite grain alignment becomes stratified and "Isostatic" graphite is not gained. This is the "Cold Isostatic Press", which Toyo Tanso pioneered in the industry.
4. Baking

By heating at approx. 1000℃, the pressed material is "carbonized" while organic elements included in the binder are removed. This process takes about one month. It is a difficult process, which requires various technical know-how about furnace temperature distribution, heating and cooling speed and so on.
5. Pitch Impregnation & Re-baking

Baked blocks are soaked in pitch under pressure for impregnation, and baked again. This process is applied to some grades only.
6. Graphitizing

Blocks are processed at approx. 3000℃ by applying electric current. Through the process, blocks are graphitized and their crystal structure is developed. And then finally Isotropic Graphite is complete. This process takes approx. two months.
7. Machining

Graphite machining uses NC etc., same as metal machining. But dry machining is suitable for graphite machining because graphite has small cutting resistance and impurities are not favorable.
8. Purification

Purification is applied to the products which are required high purity level, such as semiconductor applications. Impurities in graphite are removed by reaction with halogen based gas at high temperature.
9. Chemical Processing

Various types of coating such as Glass-like carbon coating, SiC coating, Pyrolytic carbon coating etc. are available for the products which need chemical resistance, dust prevention, improvement of surface hardness etc.
　　10. Inspection

Inspection is carried out at every process including raw materials acceptance, pulverizing, kneading etc. Besides, physical property inspection after graphitizing process, machining accuracy inspection after machining process using 3D measurement equipment etc. are conducted. Strict quality control is performed throughout the whole process.

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