Graphite mold

At present, graphite molds are widely used in the following aspects:

1. Graphite molds for non-ferrous metal continuous casting and semi-continuous casting: In recent years, advanced production methods such as direct continuous (or semi-continuous) manufacturing of rods or pipes from the molten metal state are being promoted at home and abroad. This method has begun to be used in copper, copper alloys, aluminum, aluminum alloys, etc. in China. Artificial graphite is considered to be the most suitable material as a mold for continuous casting or semi-continuous casting of non-ferrous metals. Production practice has proved that due to the use of graphite molds, factors such as good thermal conductivity (thermal conductivity determines the solidification speed of metal or alloy), good self-lubricating properties of the mold, etc., not only increase the casting speed, but also increase the casting speed due to the size of the ingot. It is precise, has smooth surface and uniform crystal structure, and can be directly processed in the next process. This not only greatly improves the yield rate and reduces waste loss, but also greatly improves product quality. There are two continuous casting methods: vertical continuous casting and horizontal continuous casting.

2. Molds for pressure casting: Artificial graphite materials have been successfully used in pressure casting of non-ferrous metals. For example, zinc alloy and copper alloy castings produced from pressurized casting molds made of artificial graphite materials have been used in automobile parts and other aspects.

3. Graphite mold for centrifugal casting: Graphite mold has been successfully used in centrifugal casting. The United States has used artificial graphite molds with a wall thickness of more than 25 mm to centrifugally cast bronze casings. In order to prevent the artificial graphite mold from burning, certain anti-oxidation measures can be taken. After casting a certain number of castings, if it is found that the inner surface of the casting mold is burned, the size of the inner hole of the casting mold can be enlarged so that it can be used to cast large-size casings.

4. Hot pressing mold: Artificial graphite hot pressing mold is used for pressure sintering of cemented carbide and has the following characteristics: First, if the pressing temperature is increased to 1350-1450 degrees, the required unit pressure can be reduced to 67-100 kgf/cm2 (i.e. 1/10 of the cold pressing pressure) is sufficient; second, pressing and heating are carried out in the same process, and a dense sintered body can be obtained after a short period of sintering.

5. Molds for glass molding: Due to the chemical stability of graphite materials, they are not susceptible to infiltration by molten glass and will not change the composition of the glass. Graphite materials have good thermal shock resistance and small size changes with temperature. Therefore, in recent years, glass has been widely used in molds. It has become an indispensable mold material in manufacturing and can be used to make molds for glass tubes, elbows, funnels and other special-shaped glass bottles.

6. Sintered molds and other diamond sintering molds: Taking advantage of the extremely small thermal deformation of artificial graphite materials, sintering molds and brackets for transistors can be manufactured. It is now widely used and 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 casting molds for various non-ferrous metals, casting molds for cast steel, casting molds for heat-resistant metals (titanium, zirconium, molybdenum, etc.) and aluminum for welding rails Heat welding molds, etc. Graphite molds for hot-pressed sintered diamond tools play the dual roles of heating elements and mold supports in the diamond tool manufacturing process. The quality of the graphite molds directly affects the dimensional accuracy and appearance of the diamond tools. Hot pressing sintering process requirements: the temperature reaches (1 000 ± 2) ℃, the molding pressure is 16 to 50 MPa, the heat and pressure holding time is 15 to 30 minutes, and the environment is in a non-vacuum state. Under this working condition, the graphite mold for molding and heating elements is required to have conductivity, high resistivity, and sufficient mechanical strength. It also needs to have good anti-oxidation properties and a long service life to ensure that the diamond Dimensional accuracy and excellent performance of tools. At present, graphite mold materials for diamond tool manufacturing in Western developed countries are mainly graphite materials with ultra-fine particle structure, high purity and high degree of graphitization. The average particle size is required to be less than 15 μm, or even less than 10 μm, and the medium pore size is less than 2 μm. Graphite molds made of this carbon raw material have small porosity, dense structure, high surface finish, strong oxidation resistance, and an average service life of 30 to 40 times. Diamond molds require high material hardness, good oxidation resistance, and high processing accuracy. The use of high-quality graphite raw materials greatly extends the service life of the mold and improves the oxidation resistance.