In the production of raw materials for plastic products, resin is the most important one, and the performance of plastics is mainly determined by it, so we mainly consider the choice of such raw materials. It should mainly meet the requirements of the use of Plastic Products, and even the design of the mold is also affected by the performance of plastic raw materials, and the flow of plastic, molding shrinkage, and use temperature must be considered when designing the mold.

(1) General principles for the selection of plastic raw materials

1) Understand the working environment of Plastic Products in detail. Any plastic product, it has its working environment, these environmental conditions have a great impact on the choice of plastic parts raw materials. It is necessary to understand the temperature of Plastic Products, whether the workplace is indoors or outdoors, what force is affected by the work, what medium is affected by the work, and voltage, temperature in the electrical environment. Then according to the environmental conditions that Plastic Products may encounter to find the raw materials that meet the environmental conditions.

2) Good processing technology. Different varieties of raw materials, the processing technology is very different, like PA and PSF of engineering plastics, in terms of technology, PA is much better than PSF.

3) Low price. In the case of meeting the requirements of use, the low price should be selected. If the working environment is 150C, the PSF can meet the requirements, rather than the PPSU with better performance and higher price.

(2) Precautions for selecting plastic raw materials

1) The linear expansion coefficient of plastic is generally larger than that of metal, and some are easy to absorb water, so the size change is large, and the gap and tolerance must be considered according to the plastic variety selected in the mold design.

2) All kinds of plastics have a certain range of use strength and allowed contact media, which should be considered when choosing.

3) Some plastics, such as PC, PS, etc., they have stress cracking phenomenon, in the design and injection to minimize stress, to avoid stress concentration in the design, strict control of the processing process and appropriate post-treatment.