Graphite material manufacturing
Isotropic graphite is made from coke, artificial graphite, natural graphite, carbon black, coal tar and asphalt,
It is made by crushing, kneading, powder screening, cold isostatic pressing, baking, graphitization and mechanical rough processing [2,3,5,10],
The manufacturing process flow is shown in Figure L-3.
Classification and properties of graphite materials
Isotropic graphite has better mechanical and physical properties than ordinary molded graphite. Common molded graphite powder
Oriented along the pressing direction, the anisotropic physical and mechanical properties of the material are anisotropic, parallel and perpendicular to the pressing direction
There is a large difference in performance, so it can not be used to process precision molds. The graphite used in EDM is isotropic stone graphite, which is different from metal materials and wood. It is a kind of heterogeneous brittleness with micro defects

Materials, with the characteristics of structural heterogeneity and porosity, have an important impact on their mechanical properties such as density, hardness and mechanical strength.. 11. When graphite is subjected to certain stress at room temperature, it tends to have less elasticity
Brittle fracture is easy to occur after deformation, and there is no obvious plastic deformation. From a macro perspective, the whole stone
The mechanical strength of each part of the ink blank is almost the same; But from the microscopic point of view, the various raw materials that constitute the graphite blank
Due to different particle sizes and materials, the mechanical strength of solid powder particles is also different, and the difference is hanging
Special. At the same time, there are many micro defects such as pores, cracks and grain boundary defects in the graphite material,
It has become the main fracture source of graphite materials [9, 10, 12L, making the actual strength of graphite much lower than its theoretical strength,
Which is the main factor affecting its fracture characteristics.
The mechanical properties of graphite mainly depend on its crystal structure, the physical property changes caused by the electronic arrangement and the mechanical properties of graphite
Raw material composition, binder, additive, particle size, mixing ratio, molding method and roasting method of graphite making materials
And graphitization conditions, etc. 191. The higher the density of graphite, the tighter the internal particle accumulation, the higher the hardness and the stronger the machinery
The better the degree. The hardness of graphite mainly depends on the nature of raw material particles. The coarser the raw material particles, the harder the graphite
The lower. The elastic modulus of graphite is proportional to the density. The higher the density, the greater the elastic modulus. The elastic modulus of graphite
The amount is relatively low, about 1 / 20.1/30 of steel and 115.1110 of glass. The compressive strength of graphite is about bending strength
The tensile strength is about half of the bending strength.