Any type of hollow plastic made by blow molding are considered blow molded plastics. Water, milk and juice bottles are all perfect examples of products made with this method used by people every day.
The Benefits of Blow Molding
Blow molding is often used because it is an efficient and simple way to produce hollow parts. The other manufacturing processes are slower and injection molding is a lot more expensive. The parts can be produced with thin walls in many sizes and shapes. Thermoplastic materials are also easy to use with blow molding.
Blow Molding Processes
Extrusion is the easiest way to make blow mold plastic parts. The parison is dropped from the extruder and put into a mold so it can be frozen into the correct shape. An extruder is set up to run continuously and a die head is attached. The result is a parison that has been clamped to a hollow mold. A blow pin is used to apply air pressure to the inside of the plastic. It is then shaped and cooled. Stretch blow molding is when the mold is injected, blown and then ejected. Injection blow molding is used for the creation of smaller containers.
This process involves molten plastic being forced through a die head with a rotating screw. The parison is formed around the blow pin then extruded vertically through the open molds of two halves. The halves then close on the blow pin and parison. This process can manufacture large amounts of parts.
The Finished Plastic Product
Secondary operations are usually required to obtain a finished product. These include heat welding, die cutting, riveting, surface treating, screwing, CNC routing, drilling, sonic, sawing, punching and milling. These steps can all be done economically when the right equipment is used.