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Plastic products annealing treatment is designed to eliminate the internal stress. The different temperature slowing down between the thick and thin area of plastic part leads to non-uniform shrinkage, which results in the phenomenon of stress concentration. As to the metal insert, it is more obvious. If not annealed ,over time, the cracks and deformation of injection part will be found on the area with the stress concentration. Annealing way: Usually the product is immersed in hot oil , hot water or circulated hot air, according to the type of plastic resin, the annealing temperature should be adjusted, generally less than the thermal deformation temperature of articles by 10 to 20 ° C, the high temperature could make products be deformed, and it can not be too low temperature, low temperature annealing can not reach the effect.
plastic conditioning is main for injection part of polyamide (nylon),because the products of this material, after it has been stored for a period of time, would be deformed of expansion due to absorbing of moisture in the air, the size will change. Therefore, after the molding of nylon materials, it should firstly be immersed in 100 ~ 120 ° C water, so that the products could be isolated from the air. the scheduled time of plastic conditioning treatment should be based on the wall thickness and shape of the article. Then, the part slowly cooled down to room temperature.