The effect of time settings on product quality in injection molding
June 27, 2022
Time setting: There are drying time, injection and holding time, cooling time, etc. in the injection molding process.
Drying time: It is the drying time of plastic raw materials, and all kinds of plastics have the best drying temperature and time. The drying temperature of ABS plastic is 80-90 ° C for 2 hours. ABS plastic is generally 24 hours, the water absorption is 0.2 to 0.4%, and the water content that can be injection molded is 0.1 to 0.2%.
Injection and pressure holding time: The control methods of the computer injection machine are equipped with multi-stage injection, gradable pressure regulation, speed regulation and adjustment of injection plastic volume. The speed of the plastic injected into the mold cavity reaches a constant speed, and the appearance and quality of the molded product are improved.
Therefore, the injection process is commonly used for position control, without time control, and the pressure is controlled by time. For example, the pressure holding time is long, the product density is large, the weight is heavy, the internal stress is large, the demoulding is difficult, the whitening is easy, and the molding cycle is prolonged. The holding time is too short, the product is prone to dents, and the size is unstable.
Cooling time: It is to ensure the stable setting of the product. It is enough to cool the molding time after the plastic injected into the mold cavity is molded into a product. Otherwise, the product is easy to warp and deform when the mold is opened, and the ejection is easy to deform and white. The cooling time is too long, and the molding cycle is extended, which is uneconomical.
