At present, graphite mold mainly in the following areas has been widely used:
1. Non-ferrous metal continuous casting and semi-continuous casting with graphite mold: In recent years, at home and abroad are being promoted by the state of molten metal directly continuous (or semi-continuous) manufacturing bar or pipe and other advanced production methods. Domestic copper, copper alloy, aluminum, aluminum and other aspects have begun to adopt this method. Artificial graphite is considered to be the most suitable material for continuous casting or semi-continuous casting of non-ferrous metals. Production practice has proved that, due to the use of graphite mold, because of its good thermal conductivity (thermal conductivity determines the solidification rate of metal or alloy), mold self-lubricating properties and other factors, not only to improve casting speed, and ingot size Accurate, smooth surface, uniform crystal structure, can be directly under the process of processing. This not only greatly improve the yield, reduce waste loss, but also a substantial increase in product quality. Continuous casting methods are vertical continuous casting method and horizontal continuous casting method two.
2.Pressure casting mold: Artificial graphite material has been successfully used in the non-ferrous metal pressure casting. For example, zinc alloy and copper alloy castings produced by the use of artificial graphite materials for molds for press casting have been used for automobile parts and the like.
3. Centrifugal casting with graphite mold: graphite mold has been successfully applied to centrifugal casting. The United States has been used for more than 25 mm wall thickness of artificial graphite mold to centrifugal casting bronze casing. In order to prevent the burning of artificial graphite die, can take some anti-oxidation measures. Casting a certain number of castings, if found inside the mold surface burned, you can mold the size of the hole in order to expand the size used to cast casing.
4. Hot stamping die: artificial graphite hot stamping die for carbide sintering with the following characteristics: First, if the suppression of temperature increased to 1350-1450 degrees, the required unit pressure can be reduced to 67-100 kgf / cm2 (that is, cold pressure of 1/10) can be; Second, pressure and heating in the same process, a short period of sintering can be dense sintered body.
5. Glass forming mold: As the graphite material with chemical stability, not vulnerable to the infiltration of molten glass will not change the composition of glass, graphite thermal shock resistance is good, the size of small changes with temperature and other characteristics, so in recent years in the glass Manufacturing become an indispensable mold material, you can use it to manufacture glass tube, elbow, funnel and other kinds of special-shaped glass bottle mold.
6. Sintering mold and other diamond sintering mold: the use of artificial graphite thermal deformation of the characteristics of a very small, can produce transistor sintering mold and stent, is now widely used, it has become an indispensable material for the development of the semiconductor industry. In addition, graphite molds are also used in casting molds for cast iron, durable molds for various non-ferrous metals, molds for cast steel, castings for heat-resistant metals (titanium, zirconium, molybdenum, etc.), aluminum for welding rails Hot-welding type of mold. Hot pressing sintering diamond tools with graphite mold, in the diamond tool manufacturing process is responsible for the heating element and mold support the dual role of the quality of graphite mold quality, directly affects the diamond tool dimensional accuracy, appearance and shape. Hot pressing sintering process requirements: temperature (1 000 ± 2) ℃, forming pressure 16 - 50 MPa, holding pressure for 15 - 30 min, the environment is non-vacuum state. Under this working condition, graphite molds of both forming and heating elements are required to have conductivity, high resistivity and sufficient mechanical strength, and also need to have good oxidation resistance and long service life to ensure that the diamond Tool dimensional accuracy and excellent performance. At present, the western developed countries for the production of diamond tools, graphite mold materials, mainly for ultrafine particle structure, high purity and high degree of graphitization of graphite materials, requires an average particle size of less than 15μm, or even 10μm below the medium pore size is less than 2μm. With this carbon material made of graphite mold, porosity, compact structure, high surface finish, strong oxidation resistance, the average service life of up to 30 - 40 times. Diamond mold material hardness, oxidation resistance, high processing precision, high-quality graphite raw materials greatly extend the life of the mold and improve the oxidation resistance.
