What are the plastic blow molding processing techniques

Plastic blow molding can be divided into injection blow molding, extrusion blow molding, stretch blow molding, and blown film method;

1. Injection blow molding. The injection molding method is used to first make plastic into a bottomed billet, and then move the billet into a blow mold to blow it into a hollow product.

Injection plastic blow molding is mainly used for processing preforms supported by metal cores; The advantages of injection blow molding are that there is no waste generated during the processing, the wall thickness of the product and the dispersion of the material can be well controlled, the precision of forming fine necked products is high, the surface of the product is smooth, and it can be economically produced in small batches. The disadvantage is that the cost of molding equipment is high, and to a certain extent, it is only suitable for small blow molded products.

2. Extrusion blow molding. The plastic is first extruded into a bottom shaped billet, and then the billet is moved to a blow mold to be blown into a hollow product.

Extrusion plastic blow molding is mainly used for processing unsupported preforms The advantages of extrusion blow molding are high production efficiency, low equipment cost, wide selection range of molds and machinery, but the disadvantages are high scrap rate, poor recycling and utilization of waste materials, limited thickness control of products and dispersion of raw materials, and the need for trimming operations after molding.

3. Stretch blow molding. Stretch blow molding is a type of blow molding that uses biaxial directional stretching. The method involves first stretching the mold longitudinally, and then inflating it with compressed air to achieve transverse stretching.

Stretch plastic blow molding processing includes two methods: extrusion stretch blow molding and injection stretch blow molding. It can process biaxially oriented products, greatly reducing production costs and improving product performance. Stretch blow molding can greatly improve the transparency, impact strength, surface hardness, and rigidity of products, and is suitable for blow molding of polypropylene and polyethylene terephthalate (PETP). Stretch blow molding includes injection molding oriented stretch blow molding, extrusion molding oriented stretch blow molding, multi-layer oriented stretch blow molding, compression molding oriented stretch blow molding, etc.

4. Blow molding film method. A method of forming thermoplastic films. The plastic is first extruded into a tube using the extrusion method, and then continuously expanded into a tubular film of a certain size with the help of air blown into the tube. After cooling, it is folded and wound into a double-layer flat film. Plastic film can be manufactured by many methods, such as blow molding, extrusion, casting, rolling, casting, etc., but blow molding is the most widely used method. This method is suitable for the manufacturing of films such as polyethylene, polyvinyl chloride, polyamide, etc.