3/4 of blow molded products are manufactured by blow molding machinery. Extrusion is the process of forcing material through an orifice or die to create a product. The extrusion blow molding process consists of 5 steps: 1. Plastic parison (extrusion of hollow plastic tube); 2. Closing the flap mold on the parison, clamping the mold and cutting the parison; Cold wall blowing type training, adjust the opening and maintain a certain pressure during cooling, open the mold, write the blown parts; 5. Trim the flash to get the finished product.

The raw material for blow molding and extrusion is high-density polyethylene, the polymer most milk is usually made of. Other polyolefins are also often processed by blow molding. Depending on the application, styrenic polymers, polyvinyl chloride, polyester, polyurethane, polycarbonate and other thermoplastics can also be used for blow molding.

Engineering plastics have recently gained wide acceptance in the automotive industry. Material selection is based on mechanical strength, weather resistance, electrical properties, optical properties and other properties.