The properties of various plastics do differ, therefore their processing methods also differ.
For example, plastic bottles made of PE and PP are manufactured by heating the raw material and injecting it into a mold for a one-time injection molding process, resulting in the finished bottle. PET material is more special.
Its processing involves two steps: first, the PET raw material is injection molded into a preform using an injection molding machine, and then the preform is blow-molded into a bottle using a blow molding machine.
The reason PET requires this special processing method is mainly because its physical and chemical properties differ from materials like PE and PP. PET has high strength and heat resistance, but it is also relatively fragile; direct injection molding can easily lead to bottle deformation or breakage.
Therefore, first injection molding into a preform, and then using a blow molding machine for secondary molding, better ensures the quality and stability of the finished product.
The reason different processing methods for different plastic materials are mainly due to differences in their thermal properties, flowability, shrinkage rate, and other characteristics.
For example, PE and PP have good flowability and can be directly injection molded; while PET has poor flowability and requires preform blow molding to obtain the desired finished product.
Therefore, when selecting an injection molding machine for plastic product manufacturing, the characteristics of the plastic material used must be fully considered, and appropriate processing methods and equipment must be chosen. For special materials such as PET, a two-step injection molding process is even more necessary to ensure the quality and performance of the final product.
