Plastic products in the processing of bubble treatment method

Bubbles often occur in the final joint of plastic products or in the thicker part of the product. Products in the model is the first surface cooling, when the outer surface has cooled, the central part is still in a hot state.

The central part contracts as it cools, while the surface of the plastic has cooled, so bubbles form from the inside, which shrinks on its own. There are many thick parts that have no bubbles when they come out of the mold, but after tens of seconds, bubbles appear in the center.

There are several cases of bubbles, with different phenomena and reasons, which are described as follows:

Thicker products, the surface fat and bulge, saw the section at the bubble, the reason may be:

The injection speed is too fast, trapping the air and causing bubbles to form.

The feeding amount is too much or too little, the injection pressure is too high, will also produce bubbles, such as appropriate adjustment of the feeding amount will improve.

If the cooling time is too short (especially for thick wall products), the solution can be cooled with cold water and cold die outside the machine.

There is decomposition of black lines in the product, which is formed due to high temperature. If the situation is not serious, the temperature can be lowered appropriately. If the whole cylinder disintegrates, the machine must be removed for cleaning.

The inlet gate of the mold is too small and the exhaust is poor, which will also produce bubbles.

Solid products have holes and blackening phenomenon:

When solid products are formed, the injection pressure should be low, and the injection speed should be slow. Otherwise, the air is covered in the products after friction and scorching under high pressure, so that there are black holes in the products. Therefore, if the injection pressure and injection speed are reduced properly, the cavity phenomenon will disappear. Can also check whether the feeding amount is too much, appropriate to reduce some of the feeding amount to improve the bubble is also beneficial.

When the thickness of plastic products is different, the thicker part of the product has small bubbles, or the thick part of the product has black bubble in it

At the same time forming several different shapes of products, we must pay attention to the size of each gate to the weight of the product, otherwise, thick products are easy to produce bubbles. At the same time, attention should be paid to the exhaust of the mold. The products often left on the front mold make the exhaust more difficult, which is easy to produce the above phenomenon.

This phenomenon can be improved by modifying the mold or increasing the pressure holding time and cooling time to reduce the insufficient pressure in the thick section. More important is that in the design of products, should try to avoid products have extra thick part.