Special graphite covering a wide range of industry have different understanding and classification of carbon products Chinese industry, electrical carbon products of natural graphite products industry and metallurgy, metallurgy is used to explain the classification of carbon products, special graphite mainly refers to high strength, high density, high purity graphite products (referred to as the three high graphite). From the three high graphite material structure can be divided into coarse grain structure, fine grain structure and fine grain structure of three kinds of molding methods are distinguished from molding special graphite, extrusion molding and special graphite isostatic pressing special graphite three categories, in addition, vibration molding can also be used in the production of special graphite. High quality special graphite, an isotropic graphite, is a kind of special graphite produced by isostatic pressing.
Not all special graphite must achieve the same high density, high strength, high purity indicators, special graphite used in different occasions, has a specific intensity, density requirements, that is, strength, density index is not the same. Many special graphite do not need to achieve high purity, ash is not the main quality index. Some special graphite does not need high strength and high density, but it needs high purity. Some special graphite, such as EDM graphite, according to different processing technology and processing objects, require different physical and chemical indicators of fine particles, graphite or superfine particles, structural graphite.
Special graphite for electrical discharge machining
EDM is a new processing technology in machinery manufacturing industry, EDM of many high hardness metal processing, and processing of complex shape, high precision parts, can be used as a tool for the anode copper material, also can use graphite materials. As a tool for EDM, the graphite material of electrode must meet the following conditions:
(1) the structure is compact and the tissue is homogeneous; there should be no coarse particles and large pores;
(2) with high mechanical strength and good processability, it can work out complex shapes or sharp angles and flakes;
(3) the graphite tool electrode has a certain loss in the process of EDM, and this loss should be as low as possible;
(4) the discharge characteristics are stable and the processing speed is faster. Therefore, graphite with fine grain structure or graphite with fine particle structure is generally used in EDM, and the physical properties of graphite are best isotropic. Therefore, the graphite material with fine grain structure is the most popular graphite material used in China's electrical discharge machining.