Manufacturing method and tools for blow molding

Extrusion blow molding is a method of making hollow thermoplastic parts. The well-known blow molding targets for hollow blow molding processing are bottles, barrels, cans, boxes and all containers for packaging food, beverages, cosmetics, pharmaceuticals and daily necessities. Large blow-molded containers are typically used for packaging of chemicals, lubricants and bulk materials. Other blow-molded products include balls, blow-molded wheels, bellows and toys. eva foam products For the car industry, fuel tanks, car shock absorbers, seat backs, center brackets, as well as armrest and headrest covers are blow molded. With regard to machinery and furniture making, blow moulded parts are casings, door frames, racks, pots or boxes with an open side.

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

Recently, engineering plastics have been widely accepted in the car industry. Material selection is based on mechanical strength, weather resistance, electrical performance, optical performance and other functions. 3/4 of blow molding products are produced by extrusion blow molding. Extrusion is the process of forcing material through a hole or die to make a product.

The extrusion blow molding process consists of 5 steps:

1. Plastic parison (extrusion of hollow plastic tube);

2. Close the flap mold on the parison, clamp the mold and cut off the parison;

3. Inflate the mold to the cold wall of the cavity, adjust the opening and maintain a certain pressure during cooling;

4. Open the mold and remove the blown parts;

5. Trim the flash to get the product.