The key elements of plastic injection molding parts




It is understood that the injection molded parts are formed and cooled and solidified in a plastic mold. Since the molding temperature and glass transition temperature required for each resin are different, the plastic mold must have a temperature adjustment system to be suitable for the molding of each resin and efficiently in production.

In the injection molding process, the temperature of the molten material in the mold is generally between 150 and 350°C, but because the mold temperature is generally between 40 and 120°C, the heat generated by the molding material will gradually increase the mold temperature. On the other hand, since the heating nozzle of the injection molding machine is in direct contact with the sprue bushing of the mold, the temperature of the nozzle is higher than the mold temperature, which will also increase the mold temperature. If you do not try to take away the excess heat, the mold temperature will inevitably continue to rise, which will affect the cooling and solidification of the molded product. Conversely, if too much heat is taken away from the mold and the mold temperature drops, it will also affect the quality of the molded product.

For plastics with low molding viscosity and good fluidity (such as polyethylene, polypropylene, polystyrene, ABS, etc.), the temperature of the plastic mold is generally required to be low (generally not less than 80°C);

For plastics with high viscosity and poor fluidity (such as polycarbonate, polysulfone, polyphenylene ether, etc.), in order to improve the filling performance, or the plastic mold is larger and the heat dissipation area is wide, the plastic mold not only needs to be equipped with a cooling system , Also need to set up a heating system to heat the mold before injection.

Some plastic molding requires the mold to be equipped with a cooling system and a heating system. When the temperature of the mold meets the requirements of the plastic molding process, the heating system can be turned off; if the temperature of the mold is higher than the requirements of the plastic molding process after a period of injection, the cooling system of the mold must be turned on to make the mold temperature at Constant temperature at the required temperature.

For small and thin-walled plastic parts, and the molding process requires that the mold temperature is not too high, it is possible to rely on natural cooling without providing a cooling device.
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