PC plastic injection molding process with air bubbles solution

PC plastic injection molding process with air bubbles is very serious, in the mold design should pay attention to the problems (including the design of the product) in order to prevent the appearance of poor return flow or uneven cooling caused by poor plastic molding, surface defects, and deterioration, generally in the mold design, should pay attention to the following points.

a = wall thickness should be as uniform as possible, and the release slope should be large enough.

b = the transition part should be a gradual, rounded transition, to prevent a sharp corner. Sharp edges produced, especially PC products must not have a gap.

c=Gating. The runner should be as wide and thick as possible, and the location of the gate should be set according to the shrinkage condensation process, and the cold material well should be added if necessary.

d=The surface of the mold should be bright and clean with low roughness (preferably below 0.8).

e= Ventilation holes. The slot must be sufficient to vent the air and the gas in the melt in time.

f=Wall thickness should not be too thin, except for PET, which should not be less than 1mm in general.

Material preparation and drying as any little impurity in the plastic may affect the transparency of the product, therefore and storage, transportation. During the process of adding material, attention must be paid to sealing and ensuring clean raw materials. In particular, the raw materials contain moisture, which will cause deterioration of the raw materials after heating, so they must be dried, and in the injection molding, the material must be added using a dry hopper.

Also note that in the drying process, the input air should preferably be filtered, dehumidified, in order to ensure that it will not contaminate the raw materials. The drying process such as transparent plastic drying process: material process drying temperature (℃) drying time (h) material layer thickness (mm)

Barrel, screw, and its accessories clean in order to prevent raw material contamination and in the screw and accessories depressions with old material or impurities, especially poor thermal stability of the resin present, so before use, after the shutdown should be cleaned with screw cleaning agent each piece so that it shall not stick to impurities, when there is no screw cleaning agent, available PE, PS and other resin cleaning screw.

When the temporary stop, in order to prevent the raw materials in the high temperature staying for a long time, causing degradation, the dryer and barrel temperature should be reduced, such as PC, PMMA and other barrel temperatures should be reduced to 160 ℃ or less. (Hopper temperature for pc should be reduced to below 100 ℃).

Transparent plastics due to high light transmission rate, inevitably require strict surface quality requirements of plastic products, there can not be any mottling, porosity, whitening. Fog halo, black spots, discoloration, poor gloss, and other defects, and thus the entire injection molding process on raw materials, equipment. Therefore, in the whole process of injection molding, the raw materials, equipment, molds, and even product design should be very careful and put forward strict and even special requirements.

Secondly, since transparent plastics are mostly high melting points and poor liquidity, in order to ensure the surface quality of the products, it is often necessary to make fine adjustments in the machine high temperature, injection pressure, injection speed, and other process parameters, so that the injection can fill the mold, and will not produce internal stress and cause product deformation and cracking. Therefore, from the preparation of raw materials, the equipment, and mold requirements, injection molding process and product raw material handling several aspects are to be strictly operated.