Moulds can be divided into four common types according to the structure and product production process, that is, pressing mould, die-casting mould, injection mould and extrusion mould.

1. Thermo-compression molding: press forming mold is also called ordinary press mold, and its processing method is to directly put the semi-finished rubber material with a certain shape into the mold, and then send it to the flat vulcanizer for pressurization and heating, and finally vulcanization molding.

Features: The mold has simple structure, strong versatility, wide range of use, simple operation, and occupies a large proportion in rubber molding products.

2.Die casting die is a method of casting liquid die forging, a process completed on a special die casting die forging machine. Its basic technological process is: the metal liquid is first cast at low speed or high speed and filled into the cavity of the mold. The mold has a movable cavity surface. It is pressurized and forged with the cooling process of the metal liquid, which not only eliminates the shrinkage cavity and porosity defects of the blank, but also makes the internal structure of the blank reach the broken grain in the forged state

A precision casting method in which molten alloy is filled under high pressure and high speed, and cooled and solidified under high pressure

3. Injection molding mold: The processing method of the injection molding mold is efficient and fast. It injects the pre heated plastic pellet material into the mold through the gating system for molding and curing.

Features: The injection mold structure is complex, the production efficiency is high, the quality is stable, and the automatic production can be realized. It is suitable for large, thick wall and changeable mold products.

4.Extrusion molding is one of the most popular plastic molding methods at present. It is applicable to all thermoplastics and some thermosetting plastics. It can be used to form various plastic pipes, bars, plates, wires and cables, profiled sections, etc. It can also be used to color, make materials and blend plastics. The quality of extruded profiles depends on the extrusion die, which is mainly composed of die head and sizing device. The rationality of its structural design is the decisive factor to ensure the molding quality of plastic parts.

Extrusion molding is mainly used to form thermal plastics, and its molding principle is shown in Figure 2-4 (taking pipe extrusion as an example). First, granular or powdered plastics are added to the hopper. Under the action of the rotating screw of the extruder, the heated plastics are transported forward along the spiral groove of the screw. In this process, the plastic continuously receives the external heating, the shearing friction heat between the screw and the material, the material and the material, and the material and the barrel, and gradually melts into a viscous flow state. Then, under the effect of the extrusion system, the plastic melt passes through the extrusion die (die) with a certain shape and a series of auxiliary devices (shaping, cooling, traction, cutting and other devices), so as to obtain the plastic profile with a certain section shape.