In the production and processing, if the bubbles of injection products can not be treated in time, it will directly affect the plastic molding. The reason for these gases may be that the temperature is too high and the plastic is degraded under long-term heating; it may also be caused by the moisture and volatile substances contained in the raw materials. Generally, the bubble is mainly in the thick wall of the product or at the last joint. The causes of bubbles are different, the phenomena are different, and the treatment methods are different, as follows:
Phenomenon 1: bubbles appear in thicker products, the surface expands, and there are bubbles on the section after cutting.
Causes and solutions:
1. The injection pressure is too high because the quantity is not well controlled in the feeding process, so it is only necessary to adjust the feeding quantity;
2. Insufficient cooling time. It can be cooled by cold pressing die outside the machine;
3. If the temperature is too high, the black line will break down in the products. If the decomposition is slight, just cool down properly. If the whole barrel is disassembled, it can only be disassembled and cleaned;
4. If the gate of the mold is too small or the exhaust is not good, there will be bubbles. This is the reason of the equipment, so we can only improve the equipment.
Phenomenon 2: there are cavities in solid products, accompanied by blackening.
In high pressure environment, air will be burnt and wrapped in the products by friction, and bubbles or cavities will appear in the solid products. In the process of solid product forming, pay attention to two key points of operation, one is to lower the injection pressure, the other is to slow down the injection speed, and the cavity phenomenon will disappear. In addition, check whether the feeding is excessive at any time, and reduce the feeding can also improve this phenomenon.
Phenomenon 3: different thickness of plastic products, thicker parts of the products bubble.
In this case, it is necessary to pay attention to that the size of each gate of the plastic products formed at the same time is equal to the weight of the products, otherwise the thick products are easy to generate bubbles; the products accumulated on the front mold of the mold will cause the above phenomenon, so it is necessary to exhaust the mold frequently; when designing the products, it is also necessary to avoid the extra thick products.