Forming die, also known as die, is made according to the shape and structure of the object in proportion to make the material become a tool of a certain shape by pressing or watering.
Different plastic moulding methods require different moulds with different principles and structural characteristics.
1. Injection Molding Mould: Plastics are melted in the heating barrel of the injection molding machine first, then driven by the screw or piston of the injection molding machine, the injection system of the nozzle and the mould enters the mould cavity, and finally hardens and finalizes the mould in the cavity. This is a simple process of injection moulding, and the mould used in injection moulding is called the injection moulding mould.
2. Extrusion moulding die: also known as machine head. Let the plastic in the viscous flow state pass through the die with specific cross-section shape under high temperature and high pressure, and then cool and set at lower temperature. The forming method used to produce the continuous profile with the required cross-section shape is called extrusion molding, and the die used for plastic extrusion molding is called extrusion molding.
3. Blow-moulding die for hollow products: The tube blank which is still in the plasticized state is extruded or injected and put into the moulding cavity while it is hot. Compressed air is immediately injected into the center of the blank to expand the tube blank and stick to the wall of the mould cavity. After cooling and hardening, the tube blank becomes a hollow product. The moulds used in this method are blow moulding moulds for hollow products.
4. Vacuum or compressed air forming die: This is a separate negative or positive die. Prefabricated plastic sheets are pressed on the periphery of the die, heated and softened, then vacuum is pumped on one side of the die, or compressed air is filled on the other side, so that the plastic sheets are attached to the die. After cooling and setting, the product is obtained. The die of this forming method has less force and less requirement, and can even be made of non-metallic materials.
5. Compression moulds: for short, press moulds. The plastic material is directly added into the open mould cavity, and then the mould is closed. Under the action of heat and pressure, the plastic becomes a flowing state and fills the cavity. Then the plastic is hardened and shaped by chemical or physical changes.
This method is called pressing moulding, and the moulds used are called pressing moulding moulds. This kind of mould is mostly used for the forming of thermosetting plastics, but also for thermoplastic plastics. In addition, there is a cold pressing die without heating, which is used for forming PTFE blanks.
6. Die-casting moulds: also known as transfer moulding moulds. The plastic material is added into the preheated feeding chamber, and then pressure is applied to the pressure column. The plastic melts under high temperature and pressure, and enters the cavity through the casting system of the mould, gradually hardening and forming. This forming method is called die-casting forming, and the mould used is called die-casting moulding. This kind of mould is mostly used for thermosetting plastic forming.