What are Bubbles and vacuum Bubbles (Bubbles) defects?

Bubbles and vacuum Bubbles (Bubbles) defects, because the center of the wall thickness of the product cooling is the slowest, the surface of the product cooling rapidly, the rapidly shrinking surface will pull the material over, the uneven volume of the molding product shrinkage caused by the thickness of the part of the hole, the water or gas in the plastic bubble becomes a bubble. Bubbles can be divided into bubbles and vacuum bubbles. Generally speaking, bubbles occurring on transparent products can be directly observed, while bubbles occurring on opaque products can sometimes not be seen from the outside and can only be found by cutting them open or other means. The appearance of bubbles will make the product filled, uneven surface. As shown in figure: Bubble and vacuum bubble (Bubbles) defect analysis and elimination method

1) Improper control of forming conditions

Many technological parameters have a direct effect on the formation of bubbles and vacuum bubbles. If the injection pressure is too low, the injection speed is too fast, the injection time and cycle are too short, the amount of feed is too much or too little, the pressure holding is insufficient, the cooling is not uniform or insufficient, and the material temperature and mold temperature control is improper, will cause bubbles in the plastic parts. Especially when high-speed injection, the gas in the mold can not be discharged, resulting in too much residual gas in the molten material. Therefore, the injection speed should be appropriately reduced. However, if the speed drops too much and the injection pressure is too low, it is difficult to exhaust the gas in the molten material, and it is easy to produce bubbles, depressions and underinjection. Therefore, the injection speed and pressure should be adjusted with special caution. In addition, bubbles and vacuum bubbles can be avoided by adjusting the injection and pressure holding time, improving the cooling conditions and controllin