How to solve the defects on the surface when processing the product

2021-03-23 15:40:07 admin

How to solve the defects on the surface when processing the product




Generally in mold processing, if you need to use injection molding equipment to process the surface of the product will have large and small defects, generally these defects will appear in the gate position, the gate position belongs to the starting position of the mold processing, so these two positions are easy to appear Problem, then we need to find a way to eliminate these defects, so that the display effect will be improved.




Defects like dark spots and subtle flaws will appear near the gate, which is the feeling when producing high-viscosity, low-fluidity materials, such as PC, PMMA, or especially ABS. When the resin flows away from the center of the surface layer of the cooled resin, a visible surface of such defects of the article may occur.




It is generally believed that such technical defects frequently occur in the filling and packing stages. In fact, dark spots appear near the gate, usually at the beginning of the injection time period. Experimental studies have shown that the occurrence of surface slip is actually due to the injection speed, more precisely the flow asset speed at the front end of the melt flow.




Even if the injection rate of the melt is constant when it enters the mold, its flow rate will change. When entering the mold gate area, the melt velocity is high, but after entering the mold cavity, the melt velocity begins to decrease. This change in flow velocity at the front end of the melt flow can cause surface defects.




One way to solve this problem is to reduce the injection speed. In order to reduce the speed of the melt flow front at the gate, the injection can be divided into several stages, and the injection speed can be gradually increased.




Another reason is that the low melting temperature of the product is a dark spot. Increasing the barrel temperature can reduce the back pressure of the screw to improve the possibility of this phenomenon. In addition, the temperature of the mold is too low to cause surface defects, and the mold temperature is a viable option to overcome the defects on the surface of the product.