From ordinary keyboards to all tiny plastic parts, plastics have an appearance in almost every respect, presenting countless different shapes and sizes. How does blow molding a Pet Preform or plastic product work?
Plastic production process
Many of these plastic products begin with a process called plastic extrusion. Back in the late 18th century, this process involved heating small plastic pellets at elevated temperatures, forcing them to form and allowing them to cool and harden. The use of a heated screw feeder helps to push the molten plastic into the mold.
After this process is completed, many of these forms are heated again for another process called sheet or film extrusion. Then, the remelted plastic is cooled and pressed by a calender roll to diffuse and harden to form a plastic sheet.
The benefits of extrusion blow molding
These sheets can be reworked in another process called coextrusion. To this end, multiple extruders are melted together and forced into a single mold. This gives the plastic product a softer feel, a smooth surface and a gripping surface.
The last plastic processing is thermoforming. This process uses a plastic sheet that is heated until it becomes soft and then pressed into the mold. Vacuum is sometimes used to force it into the complex form required.
Because plastics play such a wide range of roles, the number of processes that mold and shape them is not surprising. From the keyboard to the Pet Bottle Preform, plastic is an important industry.