Bubbles are common in our 38mm foldable pp caps production process. What is the reason for this? Let's follow Xiaobian to understand it.

First, process factors:

1, the speed is too fast, so that the molten plastic is decomposed by large shear, producing gas.

2, the local cooling of the product is too fast, the contraction is uneven, especially when the wall thickness of the product is large, the surface cooling speed is faster than the central part, in the cooling process, the plastic in the central part of the side shrinks and expands to the surface, so that the central part is filled with insufficient, forming a vacuum bubble.

3, the pressure and pressure retention is insufficient, so that the molten material is not close to the surface of the cavity, which is not conducive to the discharge of air.

4, the back pressure is insufficient, the back pressure controls the speed of the screw retreat, the back pressure is small, the speed of the screw retreat will be fast, easy to produce insufficient feed, the air brought into the material is more, too late to discharge from the feed port, resulting in a large number of bubbles.

Second, material factors

1, the raw material has moisture.

2. Mold factor

3, mold trapped gas, should maintain the mold or increase the exhaust groove.

The above is the explanation of the cause of bubbles in the bottle during the production of 38mm foldable pp caps. Do you know it after reading it? I hope it will help you.

38mm foldable pp caps https://www.plasticsproduct.com/Foldable_caps