Type Of Plastic Molding
The plastic material is first melted in a heating cylinder of the injection molding machine, and then a method of forming the melt by a reciprocating screw to push the melt into a cavity of the closed mold.
It can not only produce high-precision, high-quality products under high productivity, but also has many varieties of plastics that can be processed. The output is large (about 1/3 of the total amount of plastics) and the use is wide. Therefore, injection molding is important in plastic processing. One of the molding methods.
2. Extrusion molding
Extrusion is a method in which a plastic is continuously passed through a die in a flowing state by heating and pressurizing in an extruder.
It is generally used for the forming of sheet, pipe, monofilament, flat wire, film, wire and cable, etc. It has wide application and high output. Therefore, it is one of the important molding methods in plastics.
3. Foam molding
It refers to the addition of a suitable foaming agent to the foaming material to produce a porous or foamed product. The foamed product has the advantages of low relative density, high specific strength, low raw material dosage, sound insulation and heat insulation, and foaming material. There are PVC, PE and PS.
Products include: film, sheet, pipe, and profiles. Foaming can be divided into chemical foaming and physical foaming.
4. Injection blow molding
Injection blow molding is a blow molding method. The plastic is first formed into a bottomed parison by injection molding, and then moved into a blow mold to be blown into a hollow product.
This method can produce packaging containers for daily necessities, cosmetics, medicines, foods, etc., but the volume should not exceed 1L. Commonly used plastics are polyethylene, polystyrene and polyvinyl chloride.
5. Extrusion blow molding
Extrusion blow molding is a blow molding method. Unlike injection blow molding, its parison is manufactured by extrusion.
6. Stretch blow molding
Stretch blow molding is a blow molding method. It is formed by extrusion, injection molding, etc., and then the parison is heated to the stretching temperature. The longitudinal stretching is carried out by mechanical action of an internal (e.g., a mandrel) or an external (e.g., a jig), and at the same time or later, by compression of the compressed air, transverse stretching is performed.
7. Blow molding
Blowing (expansion film) plastic (or hollow blow molding) refers to a molding process in which a hot thermoplastic parison or sheet in a closed mold is inflated into a hollow product by means of fluid (compressed air) pressure.
A plastic container produced in this way. Such as various bottles, squares, round or flat barrels, fuel tanks, etc. have been widely used. Newly developed various industrial parts and daily-use products, such as double-walled box-shaped products, L-ring large drums, pallets, surfboards, seat backs and desks. As well as front spoilers, belt covers, instrument panels, air conditioning ducts, etc. for automobiles, they have been applied in practice. The processed materials have evolved from household plastics to engineering plastics. Blow molding has now become one of the important molding methods in plastic processing.
But the basic steps of the blow molding process are:
(1) molten material;
(2) forming a molten resin into a tubular or parison;
(3) sealing the hollow parison blow mold;
(4) inflating the in-mold parison;
(5) cooling the blow molded product;
(6) taking out the product from the mold;