Phenomenon of Product Air Bubbles in Injection Molding Machine and Its Treatment Method

Phenomenon of Product Air Bubbles in Injection Molding Machine and Its Treatment Method



Phenomenon of product air bubbles in injection molding machine and its treatment method

In the production process, if the bubbles generated in the injection product cannot be processed in time, it will directly affect the plastic molding. The cause of these gases may be excessively high temperature and degradation of plastics when heated for a long time; it may also be caused by the moisture and volatile substances in the raw materials. Usually, the appearance of bubbles is mainly in the thick wall of the product or at the final joint. The causes of bubbles are different, the phenomena that appear will be different, and the treatment methods will be different, as follows:

Phenomenon 1: Air bubbles appear on thicker products, the surface swells, and there are bubbles on the section after cutting.
Causes and solutions:
1. In the feeding process, the amount is not controlled well, which causes the injection pressure to be too high, only need to adjust the feeding amount;
2. Insufficient cooling time. The cold press mold can be used outside the machine to cool down;
3. If the temperature is too high, black lines will decompose in the product. If the decomposition is slight, only need to cool down appropriately. 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 poor, bubbles will also appear. This is the cause of the equipment, and the equipment can only be improved.

Phenomenon 2: There are voids in the solid product, accompanied by blackening.
In a high-pressure environment, air will scorch the product through friction and be wrapped in the product, and bubbles or cavities will appear inside the solid product. When forming solid products, pay attention to two points of operation. One is to lower the injection pressure, and the other is to slow down the injection speed, and the void phenomenon will disappear. In addition, check whether the feed is excessive at any time, and reduce the feed to improve this phenomenon.

Phenomenon 3: For plastic products with different thicknesses, bubbles appear in thicker parts.

In this case, it is necessary to pay attention to the size of each gate of the plastic products formed at the same time and the weight of the product, otherwise thick products will easily produce bubbles;
The product accumulated on the front mold of the mold will cause the difficulty of venting, and the above phenomenon will also occur. The mold must be vented from time to time; when designing the product, it is also necessary to avoid the appearance of extra-thick products.


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