Introduction to the Types of Plastic Molding

Introduction to the Types of Plastic Molding

Table of content

1. Injection molding: 

It is a method in which the plastic is heated and melted in the heating barrel of the injection molding machine in advance, and then the melt is pushed into the cavity of the closed mold by the reciprocating screw. It can not only produce high-precision and high-quality products under high productivity, but also has a wide variety of plastics that can be processed, with large output (about 1/3 of the total amount of plastics) and wide applications. And there is custom injection molding for custom service. Therefore, injection molding is one of the important plastic molding methods in plastic processing.


2.Extrusion molding: 

Extrusion is a method in which the plastic is continuously passed through the die in a flowing state by heating and pressurizing in an extruder. Generally something used for plates are: pipe, monofilament, flat wire, thin film. The molding of wire and cable coating, etc., has a wide range of uses and high hield. Therefore, it is one of the important molding methods in plastic processing.


3. Foam molding: 

It refers to the addition of foaming materials with appropriate foaming agents to produce porous or foamed products. The foamed products have low relative density, high specific strength, low raw material consumption, sound insulation, heat insulation, etc. For volt points, foam materials include PVC, PE, PS and so on. Products include: films, plates, pipes, and profiles, etc. Foaming can be divided into chemical foaming and physical foaming.


4. Blow molding: 

Blow (expanded film) molding (or hollow blow molding) refers to a molding in which the hot thermoplastic parison or sheet in the closed mold is blown into a hollow product by means of fluid (compressed air) pressure. Plastic containers produced in this way. Such as various bottles, square, round or flat barrels, gasoline tanks, etc. have been widely used, newly developed various industrial parts and daily products, such as double-walled box-shaped products, L-ring large drums, palletizing plates, surfboards, seat backs and desks, as well as automobile front spoilers, belt covers, instrument panels, air-conditioning vent pipes, etc., have been applied in practice. The processed materials are from daily plastics to engineering plastics. Now blow molding has become one of the important molding methods in plastic processing.

But the basic steps of the blow molding process are: ①melt the material; ②form the molten resin into a tube or parison; ③melt and seal the hollow parison in the blow mold; ④ inflate the in-mold parison; ⑤cool the blow molded product;⑥ Take out the product from the mold; ⑦ Trim.


5. Injection blow molding: 

Injection blow molding is a blow molding method. Firstly, the plastic is made into a bottomed parison by injection molding, and then it is moved to a blow mold to be blown into a hollow product. This method can produce packaging containers for daily necessities, cosmetics, medicine, food, etc. But its volume should not exceed 1L which commonly used are polyethylene, polystyrene and polyvinyl chloride, etc.


6.Extrusion blow molding: 

Extrusion blow molding is a blow molding method. Different from injection blow molding, its parison is made by extrusion.

7.Stretch blow molding: 

Stretch blow molding is a blow molding method. It uses extrusion and injection molding to make the parison. The parison is then heated to the stretching temperature. Longitudinal stretching is performed by internal (such as mandrel) or external (such as clamps) mechanical force. At the same time or later, it is inflated by compressed air for transverse stretching.