How are plastic bottles made?

We see or even drink from plastic water bottles everday! Ever wonder how are those plastic bottles made? By blow molding! Yes, this is a process used for plastic bottles manufacturing. With the help of gas pressure, the hot melt parison closed in the mold is inflated to form a hollow product. Blow molding is divided into extrusion blow molding and injection blow molding. Extrusion blow molding has lower mold cost, while injection blow molding provides more controllable parameters, such as wall thickness and weight.

How are plastic bottles made?

Plastic blow molding process includes several standard steps:

• The parison is installed on the nozzle of the machine, and then put into the mold. The mold is divided into two halves.
• The hot air passes through the blowing head to form a blank and expand to the shape of the mold.
• Cooling in the mold for a few seconds, cooling before demolding.
• Remove the extra material at both ends, and finally complete the product.

Blow molding is mainly used to produce thin-walled hollow plastic products, such as water or soda bottles, pipes, car bumpers, and so on. Most thermoplastics include PET, PS, PC and other materials can be processed by blow molding, as well as glass. For the production of asymmetric parts, extrusion blow molding is usually used. In the blow molding process, injection molding is done on the parison and then moved to the blow molding machine for injection blow molding process.

For economy scale, it is necessary to produce hundreds to thousands of pieces of plastic bottles per hour, so blow molding manufacturing is generally mass production. With the improvement of the technology level, the cost of equipment decreases, one worker can control the operation of multiple automated equipment, and the labor cost is thus largely reduced.