Forming Process Of Graphite Material
Graphite material molding is mainly to improve the density of the mixture powder, so that aggregate and binder close contact, in order to obtain a certain size, morphology and processing margin of green. There are many molding methods, the main methods are extrusion molding, molding, vibration molding and isostatic pressing molding.
Molding of graphite materials
The molding adopts the vertical press. First, the mold is made according to the shape and size of the product. Then, a certain amount of mixed and kneaded powder is loaded into the mold on the working platform of the press, and the press is started to exert pressure on the powder and maintain a certain period of time to make it into shape. Then the pressed green blank is ejected from the mold.
Mould pressing method can be divided into unidirectional pressing and bi-directional pressing, cold pressing and hot pressing according to different process and equipment. Mould pressing method is suitable for pressing products with small size in three directions, small difference in size in three directions, uniform density and high density, but the products are anisotropic. It is mainly used for the preparation of electro-carbon products and special graphite, relative extrusion molding, molding in the production of special graphite is more widely used.
Isostatic pressing of graphite materials
The principle of isostatic pressure is Pascal’s law: the pressure applied to a closed container (liquid or gas) can be equally transmitted in all directions, and the pressure on the surface under its action is proportional to the area of the surface.
Isostatic pressing technology is usually divided into cold isostatic pressing (CIP), warm isostatic pressing (WIP) and hot isostatic pressing (HIP) according to the temperature of forming and consolidation. Due to the different temperature and pressure medium, the three different types of isostatic pressing technology are respectively equipped with corresponding equipment and die materials.
Isostatic pressure forming technology is to place the specimen to be pressed in a high pressure cylinder which is packed in an airtight envelope. By using the incompressible property of liquid medium and the property of uniform transmission of pressure, the specimen is uniformly pressed from various aspects. When the fluid medium is injected into the pressure cylinder, according to the principle of fluid mechanics, the pressure strength is transferred unevenly to the cylinder in all directions. The pressure in the high-pressure cylinder is uniform and uniform in all directions.
Isostatic pressing can produce all kinds of homogeneous and heterogeneous products, and its products have uniform structure, high density and strength. Generally used in the production of special graphite, especially the production of large-size special graphite products.
