How does a blow molding factory blow out hollow products?

Blow molding is one of the important processing methods for thermoplastic materials, which can be used to process films and hollow products such as bottles and barrels. The barrels or bottles produced by blow molding factories can be round or flat, and are suitable for molding and processing various thermoplastic plastics such as PE, PP, PVC, PC, PET, etc.

1、 Main equipment of blow molding processing plant

Extrusion blow molding equipment mainly consists of extruders and blow molds, while injection blow molding mainly consists of injection molding machines and blow molds.

2、 Introduction to other blow molding processes

1）. Multi layer blow molding

The products processed by multi-layer blow molding technology are composed of multiple layers of raw materials. The structures commonly used by blow molding factories include PA/PPO, PVA/PPO, PE/PVC/PE, PS/PAN/PP, etc. The processes include co extrusion blow molding and multi-layer injection blow molding.

Co extrusion blow molding is a processing method that uses several extruders to simultaneously squeeze the plasticized resin into multiple layers of machine heads, and then passes it through a core rod to form multiple layers of preforms, followed by blow molding.

Multi layer injection molded containers have good air tightness and are mainly used for packaging cosmetics, drugs, and food.

2）. Stretch blow molding process

The stretch blow molding process is a processing method that uses injection molded blanks to stretch at a softening temperature and then blow molded. Stretch blow molded products have good transparency, improved tensile strength, impact strength, surface hardness, rigidity, and airtightness. This method is particularly suitable for materials such as PET and PP.

3）. Extrusion, stretching, and blow molding

Extrusion, stretching, and blow molding are used to produce plastic bottles. The process involves first using extrusion to melt the resin into a tubular billet, then fusing the bottom of the billet into a bottomed billet, and then processing the billet to the ideal stretching temperature for longitudinal stretching and blowing to produce a hollow bottle. This method is mainly used for processing PP raw materials, and the products are mainly small thin-walled bottles. By using this process for processing, the impact toughness, low-temperature strength, transparency, surface gloss, and rigidity of the product have all been improved or enhanced.

4）. Injection, stretching, and blow molding

The injection stretch blow molding process mainly produces PP, PET or PVC bottles. The process involves first injecting molten resin into a bottomed billet, then heating the billet and stretching and blowing it to form a bottle body.

This method is similar to the extrusion stretching blow molding method, but the process has no burrs and saves raw materials.

5）. Extrusion blow molding

Extrusion blow molding mainly produces large hollow containers (large hollow containers generally refer to hollow products such as barrels, tanks, storage tanks, and boxes with a volume of>50L). During the processing of large containers, due to the weight of the billet, slow extrusion by an extruder alone can cause the billet to sag, resulting in uneven wall thickness, and prolonged extrusion time can cause the surface of the billet to be cooled, which will affect the quality of the container. Therefore, during the production of extrusion blow molding, a storage device is installed at the front end of the extruder to store the molten material first, and then the extrusion molding is carried out.