Uniform plastic requires strict surface quality requirements for plastic products due to low light transmittance, and must not have any spots, pores, or whitening. Mist halo, black spots, discoloration, poor gloss and other defects affect the entire injection molding process for raw materials and equipment. The design of molds and products should pay great attention to and put forward strict and specific requirements.

Secondly, due to the low melting point and low fluidity of uniform plastic, in order to ensure the surface quality of the product, it is often necessary to make small adjustments to process parameters such as machine temperature, injection pressure, and injection speed, so that not only can the mold be filled with plastic during injection, but also internal stress will never be generated, resulting in product deformation and cracking. So, in terms of raw material preparation, strict operations must be carried out in terms of equipment and mold requirements, injection molding process, and raw material treatment of products.

1、 The preparation and dampness of materials may affect the transparency of the product due to the presence of any impurities in the plastic, which is related to storage and transportation. During the feeding process, it is necessary to pay attention to sealing to ensure the cleanliness of the raw materials. Especially when the raw materials contain moisture, heating can cause them to deteriorate, so they need to be damp and a dry hopper must be used for feeding during injection molding.

It should also be noted that during the humid process, the input air should undergo filtration and dehumidification to ensure that it will not contaminate the raw materials. Its wet process, such as uniform plastic wet process: material process wet temperature (℃) wet time (h) material layer thickness (mm) Remarks: pmma70-802-430-40pc120-130 ＞ 6 ＜ 30 Use hot air circulation drying for pet140-1803-4 Use interval wet feeding device as a poor choice.

2、 The cleaning of the barrel, screw, and accessories is used to prevent contamination of raw materials and the presence of old materials or impurities in the screw and accessory recesses, especially in the presence of resin with poor thermal stability. Therefore, after use and shutdown, screw cleaning agents should be used to clean all parts to ensure that there are no impurities attached. If there is no screw cleaning agent, resins such as PE and PS can be used to clean the screw.

When the machine is temporarily shut down, in order to prevent the raw materials from staying at high temperatures for a short time and causing temperature drop, the temperature of the dryer and the machine barrel should be reduced, such as the temperature of the PC, PMMA, and other machine barrels should be reduced to below 160 ℃. The temperature of the hopper should drop below 100 ℃ for PC.

3、 The issues that should be paid attention to in mold design (including product design) to prevent the occurrence of continuous backflow or cooling, which will never cause improper plastic molding, resulting in surface defects and deterioration. Generally, when designing molds, the following points should be noted:

A=The wall thickness should be as uniform as possible, and the demolding angle should be small enough;

B=The transition part should be gradual. Smooth transition to prevent sharp corners. Sharp edges, especially in PC products where you have gaps;

C=Gate. The flow channel should be as wide and short as possible, and the gate position should be set according to the shrinkage and condensation process. If appropriate, a cold material well should be added;

D=The surface of the mold should be smooth and clean, with a high roughness (preferably less than 0.8);

E=exhaust hole. The slot must be sufficient to timely exhaust air and gas from the melt;

F=Except for PET, the wall thickness is very thick, usually not less than 1mm.