Plastic Extrusions Key Terms

Get familiar with the basic terminology of plastic extrusions

By Howard Robertson

Plastic extrusion is a manufacturing process through which plastic is melted and shaped into a continuous profile. This process is useful for the production of a wide variety of products, including pipes, frames and channels.

If you want to be a supplier of plastic extrusion products, you will need to get acquainted with various technical terms associated with the extrusion process and the different types of plastics. This guide covers some technical terms, such as resin, thermoplastic and polymer.

Resin

Resin is a solid or semi-solid organic (carbon based) material, either natural or synthetic. Various resin materials are used for manufacturing plastic extrusion products.
Try: wiseGEEK, an information resource, provides explanation about the different types of resins.

Polymer

Polymer compounds have a large molecule composed of many smaller molecules linked together. The process of forming a polymer by combining large numbers of chemical units or monomers into long chains is called polymerization.
Try: Chemicals Technology, an informative website, offers definitions for various technical terms, such as polymer. In addition, you can read through detailed information on polymer at the Laboratory of Atomic and Solid State Physics at Cornell University.

Thermoplastic

A thermoplastic is a polymer that melts on heating and solidifies to a very glassy state on cooling. Thermoplastics can go through melting/freezing cycles repeatedly. This quality makes this polymer an ideal material for plastic extrusion products.
Try: You can read through the glossary of electrical terms at Röchling Glastic, a supplier of high performance composites. General Composites is another composite supplier that provides definitions for various terms, including polymer and thermoplastics.

Thermoset

Unlike thermoplastic, a thermoset polymer can not be melted/frozen repeatedly. A thermosetting plastic hardens permanently on cooling and you will need to consult an expert if you want to extrude thermoset plastics.
Try: Mid-Michigan Society of Plastics Engineers (PDF), a knowledge resource for plastics industry professionals, offers information about thermoset plastics. In addition, you can read through information at Knowledgerush.com.

Hot extrusion

As the name indicates, hot extrusion is carried out at high temperatures. At higher temperatures, the yield strength of the plastic is less than its value at room temperature.
Try: You can read through an explanation of the hot extrusion process at GlobalSpec, an online information resource.

Cold extrusion

The cold extrusion process is carried out at room temperature. However, extrusion at room temperature might induce some stresses in the extruded product.
Try: You can read through the cold extrusion process at Heckler AG, a metal forming company.

Purging

Purging is the process of cleaning one type of material or color from an extruder by forcing it out with a new material or color.
Try: You can read through the basics of purging at Xaloy Inc. (PDF), a service provider of plastic extrusions.

Billet

A billet is the raw, solid material kept in the extrusion die for further processing. Dimensions of the plastic extrusion products depend upon the billet dimensions.
Try: Automation Supplies, a manufacturer of aluminium extraction frameworks, provides information on billet.