Plastic Injection Mould Improve Hardness And Wear Resistance
Reasonable choice of Plastic Injection Moulding materials, Plastic Injection Mould design is the primary task, the general requirements of the Plastic Injection Mould material have the following aspects.
1. Easy to process, Plastic Injection Mould parts are made of metal materials, and some structural shape is still very complex, in order to shorten the production cycle, improve efficiency, require Plastic Injection Mould material easy to process into the drawings required shape and accuracy.
2. Good wear resistance Plastic surface gloss and precision and Plastic Injection Mould cavity surface wear resistance is directly related to, in particular, some plastic added to the glass fiber, inorganic fillers and some pigments, they and plastic Melt together in the runner, cavity in the high-speed flow, the friction on the cavity surface is very large, if the material is not wear, and soon will wear, so that the quality of plastic parts damage.
3. High corrosion resistance Many resins and additives on the cavity surface corrosion, this corrosion to the cavity surface metal corrosion, peeling, the surface condition deteriorated, the quality of plastic parts worse. Therefore, it is best to use corrosion-resistant steel, or the chrome surface of the cavity, nickel plating.
4. Good dimensional stability In the injection Plastic Injection Moulding, Plastic Injection Mould cavity temperature to reach more than 300 ℃. To this end, it is best to use the appropriate tempering treatment of the tool steel (heat treatment steel). Otherwise it will cause changes in the microstructure of the material, resulting in changes in Plastic Injection Mould size.
5. Heat treatment effects in order to improve the hardness and wear resistance, the general Plastic Injection Mould to be heat treatment, but this treatment should make its size change is very small. Therefore, it is preferable to use pre-hardened steel capable of cutting.
6. Good polishing performance Plastic parts usually require a good gloss and surface conditions, so the surface of the cavity surface roughness is very small, so that the surface of the cavity must be surface processing, such as polishing, grinding and so on. Therefore, the choice of steel should not contain rough impurities and pores and so on.
The factors that affect the cooling of the injection Plastic Injection Mould are many, such as the shape of the plastic parts and the design of the parting surface, the type of the cooling medium, the temperature, the flow rate, the geometrical parameters and the spatial arrangement of the cooling pipe, the Plastic Injection Mould material, the melt temperature, Temperature and Plastic Injection Mould temperature, plastic parts and plastic Plastic Injection Mould interaction between the thermal cycle.
(1) low Plastic Injection Mould temperature can reduce the Plastic Injection Moulding shrinkage of plastic parts.
(2) Plastic Injection Mould temperature uniformity, cooling time is short, the injection speed can reduce the plastic parts of the warping deformation.
(3) for the crystalline polymer, to improve the Plastic Injection Mould temperature can make plastic parts size and stability, to avoid post-crystallization phenomenon, but will lead to extension of the Plastic Injection Moulding cycle and plastic parts brittle defects.
(4) As the crystallinity of the crystalline polymer increases, the resistance to stress cracking of the plastic is lowered, so that it is advantageous to reduce the Plastic Injection Mould temperature. However, for high viscosity amorphous polymers, due to its endurance cracking and plastic parts of the internal stress is directly related to improve the Plastic Injection Mould temperature and filling speed, reduce the feeding time is favorable.
(5) to improve the Plastic Injection Mould temperature can improve the surface quality of plastic parts. Plastic Injection Mould temperature to determine the injection Plastic Injection Moulding process, the Plastic Injection Mould temperature directly affects the plastic filling, plastic parts stereotypes, Plastic Injection Moulding cycle and plastic parts quality.
The temperature of the Plastic Injection Mould depends on the plastic crystallinity, plastic parts size and structure, performance requirements and other process conditions such as melt temperature, injection speed, injection pressure and Plastic Injection Moulding cycle. For amorphous polymers, the melt is solidified as the temperature decreases after being injected into the Plastic Injection Mould cavity, but does not undergo phase transformation. The Plastic Injection Mould temperature mainly affects the viscosity of the melt, i.e., the filling rate.
Therefore, for lower and medium-sized amorphous plastics such as polystyrene, cellulose acetate, etc., using a lower Plastic Injection Mould temperature can shorten the cooling time.