What Steps Are Included In The Post-processing Of Injection Molded Parts

Due to uneven plasticization or due to the crystallization, orientation and cooling of plastic in the cavity and the influence of metal inserts. Some internal stress inevitably exists inside the injection molded parts, which leads to deformation and cracking of the injection molded parts during use. To solve these problems in the future, some appropriate post-treatments can be performed on the plastic parts. The commonly used post-treatment methods include annealing and There are two types of humidity control.

Annealing treatment of injection molded parts, annealing treatment is a heat treatment process in which injection molded parts are placed in a heating medium at a constant temperature, such as hot water, hot oil, hot air, etc., and kept warm for a period of time. The heat during annealing can accelerate the relaxation of macromolecules in the plastic, thereby eliminating the residual stress after injection molding. The annealing temperature is generally selected and controlled from 10 to 20 degrees above the service temperature of the injection molded part to 10 to 20 degrees below the heat distortion temperature. . The holding time is related to the type of plastic and the thickness of the injection molded part. Generally, it can be calculated as about half an hour per millimeter. When cooling and returning the product, the cooling speed should not be too fast, otherwise stress will occur.

Humidity conditioning treatment, humidity conditioning treatment is a post-processing tool to adjust the water content of injection molded parts, mainly used for plastic products such as polyamide with strong hygroscopicity and easy oxidation. In addition to eliminating residual stress under heating conditions, humidity conditioning treatment can also make plastic parts reach a moisture absorption balance in the heating medium to prevent dimensional changes during use. The medium used in the humidity control treatment is generally boiling water or potassium acetate solution, and the heating temperature is 100-121 degrees. When the heat distortion temperature is high, take the upper limit, otherwise take the lower limit, the holding time is related to the thickness of the injection molded part, usually 2~9h.

Effectively mastering the post-processing method of injection molded parts can effectively increase the qualified rate of injection molded products.

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