Mold material should have the performance
(1) high mechanical properties and wear resistance in order to increase the rigidity of the plastic parts, widely used in glass fiber, inorganic filler in plastics formula to enhance, after the people of these additives, they with molten material into the mold cavity, high-speed friction within the mold cavity is great, if the mould material wear-resisting, easily make cavity by excessive wear, therefore, make this kind of mould materials especially should have good wear resistance.
(2)Many additives of plastics, such as flame retardants, and even the chemical action of the melt itself will corrode the mold cavity.When mixed with plastic raw materials containing abrasive fillers and reinforced material, are more likely to exacerbate mold damage, to this, it is best to use corrosion resistant steel, or to the mold surface treatment, electroplating chromium plated or nickel plated.
(3)In the process of injection molding, good mould temperature control greatly affects the quality of plastic parts, especially in the process of semi-crystalline thermoplastic plastics.Generally, copper alloys have much better thermal conductivity than alloy steels, but their elastic modulus, hardness and durability are lower.The lack of heat conductivity of steel can be compensated by a cooling system.
(4) good dimensional stability in the forming operation of injection moulds, the temperature of the mold cavity to reach above 300 ℃, the temperature difference is so big, easy to produce micro cavity structure changes, resulting in the mold size change, make the plastic parts size is not stable, therefore, can choose suitable tool steel tempering treatment, the heat treatment of steel.In order to improve the hardness and wear resistance, heat treatment is usually carried out on the molds.However, this heat treatment should have the least impact on the size of the mold. Prehardened steel that can be machined can be used.
(5) good polishing performance high demand for mold cavity wall, the roughness is very small, so as to adapt to the requirement, good gloss on the surface of the plastic, the mold cavity generally must carry on the polishing processing, surface as light as possible, therefore, request mould material is easy to polish, chooses the material should not have impurities and defects such as porosity.