The content of moisture and volatile matter in the raw materials is too high. The melt index of the raw materials is too large, and too much lubricant is used. The raw materials require high temperatures to be plasticized, such as PBT, PPS, etc.

In terms of molding operation, the injection speed is too high, the temperature of the melt is high, and the injection pressure is high.

Linear traces on the surface of plastic parts are formed by the plastics coming together in the mold, and the melts are not completely fused together at their intersections, and they cannot melt into each other, resulting in welding lines, which usually appear as a straight line. It develops from deep to shallow, and this phenomenon has a certain impact on the appearance and mechanical properties. Such as the weld marks on the bottom of the hook plate.

The shape of the plastic part will rotate and twist after the plastic part is demoulded or for a period of time later, such as straight edges facing inward or outward, or flat parts with undulations, such as shift forks, reinforced seats, etc., with local and partial deformations. Overall deformation.

Metal stamping is to place a metal plate in the mold of the stamping machine. The plate is pressed down by the stamping machine according to the shape of the mold to obtain a product. This process is metal stamping.