As a polymer, plastic has now become one of the most widely used materials for human beings. Because of its flexible molding process, it is widely used in various fields. Generally speaking, the most common plastic molding processes are injection molding, extrusion molding and blow molding. But when it comes to secondary molding, three moldings are even more.
1. Injection molding
The main method of processing plastics is injection molding. In this process, the plastic is placed in a hopper, then heating and injects the plastic, which is pushed through a long chamber with a reciprocating screw. It is then softened into fluid state. The nozzle is located at the end of the chamber, and the fluid plastic is forcedly cooled through the nozzle, close the mold. When the plastic is cooled and solidified, the semi-finished plastic product is ejected from the press.
The extrusion process is usually used to make films, sheets, tubes, profiles, rods, jacket wires, filaments, wires, and cables. With the injection molding machine, the dry plastic is placed in a hopper and fed into a long heating chamber. At the end of the chamber, the material is pressed out with a small opening, or in the shape of the desired end product mold. After the plastic leaves the mold, it is placed on a conveyor belt and cooled. Blower is sometimes used during this process to help cool it down.
3. Blow molding
The sheet is clamped on the frame and heated into softened state, and it is brought into close contact with the mold surface under the action of an external force to obtain a shape similar to the mold surface. After cooling and shaping, the product is finished after trimming. This process is also used in rubber processing.
5. Compression Molding
8. Vacuum Forming
9. Rotational Molding