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Comparison of advantages and disadvantages of extrusion, injection molding and blow molding of three plastic film forming processes
Plastic molding is an engineering technology that involves various processes that transform plastics into plastic products.
injection molding
The principle of injection molding is to add granular or powdery raw materials into the hopper of the injection machine, and the raw materials are heated and melted into a flowing state. Under the push of the screw or piston of the injection machine, they enter the mold cavity through the nozzle and the pouring system of the mold. , hardened and shaped in the mold cavity. Factors affecting the quality of injection molding: injection pressure, injection time, injection temperature.
advantage:
1. Short molding cycle, high production efficiency, and easy automation
2. It can form plastic parts with complex shapes and precise dimensions, with metal or non-metal inserts
3. Stable product quality
4. Wide range of adaptation
shortcoming:
1. The price of injection molding equipment is higher
2. The structure of Wholesale Polyester Printing Canvas the injection mold is complex
3. The production cost is high, the production cycle is long, and it is not suitable for the production of single and small batches of plastic parts
application:
Among industrial products, injection-molded products include: kitchen supplies (garbage cans, bowls, buckets, pots, cutlery, and various containers), housings for electrical equipment (hair dryers, vacuum cleaners, food mixers, etc.), toys and games, automobiles Various industrial products, parts of many other products, etc.
Extrusion
Extrusion molding: Also known as extrusion molding, it is mainly suitable for the molding of thermoplastics, and also suitable for the molding of some thermosetting and reinforced plastics with good fluidity. The molding process is to use the rotating screw to extrude the heated and melted thermoplastic material from the die head with the desired cross-sectional shape, then shape it by the shaper, and then pass it through the cooler to make it harden and solidify to become the desired cross-sectional shape. product.
Process features:
1. Low equipment cost;
2. The operation is simple, the process is easy to control, and it is convenient to realize continuous automatic production;
3. High production efficiency; uniform and dense product quality;
4. Products or semi-finished products with various cross-sectional shapes can be formed by Wholesale Sparkling Lamination PVC film changing the die of the die.
application:
In the field of product design, extrusion molding has strong applicability. The types of extruded products include pipes, films, rods, monofilaments, flat belts, nets, hollow containers, windows, door frames, plates, cable cladding, monofilaments and other profiles.
blow molding
Blow molding: The molten thermoplastic raw material extruded from the extruder is clamped into the mold, and then air is blown into the raw material. The molten raw material expands under the action of air pressure, fits to the wall of the mold cavity, and finally cools. The method of curing into the desired product shape. Blow molding is divided into film blow molding and hollow blow molding:
Film blow molding:
Film blow molding is to extrude the molten plastic from the annular gap of the extruder die into a cylindrical thin tube, and at the same time blow compressed air into the inner cavity of the thin tube from the central hole of the die to inflate the thin tube to a diameter Larger tubular films (commonly known as bubble tubes) are coiled after cooling.
Hollow blow molding:
Hollow blow molding is a secondary molding technology that uses gas pressure to inflate a rubber-like parison closed in a mold cavity into a hollow product. It is a method of producing hollow plastic products. According to the different manufacturing methods of the parison, hollow blow molding includes extrusion blow molding, injection blow molding, and stretch blow molding.
1) Extrusion blow molding: Extrusion blow molding is to extrude a tubular parison with an extruder, clamp it in the mold cavity and seal the bottom while it is still hot, and then blow compressed air into the inner cavity of the tube blank for inflation.
2) Injection blow molding: The parison used is obtained by injection molding. The parison is left on the core mold of the mold. After the blow mold is used to close the mold, compressed air is introduced from the core mold to inflate the parison, cool it, and demold the product to obtain the product.
3) Stretch blow molding: The parison that has been heated to the stretching temperature is placed in the blow mold, longitudinally stretched with a stretching rod, and transversely stretched with blown compressed air, so as to obtain the product of method.
advantage:
The product has uniform wall thickness, small weight tolerance, less post-processing, and small waste corners; it is suitable for the production of small refined products with large batches.
application:
Film blow molding is mainly used to make plastic thin molds; hollow blow molding is mainly used to make hollow plastic products (bottles, packaging barrels, watering cans, fuel tanks, cans, toys, etc.).
