How Does an Extruder Work?

Plastic can be extruded into solids or into hollow tubes to be used as pipes.

Extrusion readies plastic materials to be turned into plastic products. The raw materials of the extrusion process are plastic pellets called resin. These pellets can be made specifically for extrusion or the resin can be made from previously used plastic products. This is one way to recycle plastic.

Purpose

The extrusion process liquefies plastic so that it can be reshaped and formed into different solid pieces. The new plastic solid tubes or sheets can be cut, rolled or formed in different ways to produce plastic products.

Process

Plastic pellets are placed into a hopper, then a jack-screw pushes the pellets through a heated barrel where they melt. The jack-screw pushes the molten plastic into a metal die to shape the plastic. The newly shaped plastic piece passes through a cooling apparatus and is then is ready to be cut, packaged or formed into different products.

Applications

Applications for extruded plastics vary according to their composition and the dies used to shape them. For instance, extrude PVC plastics are used in construction, while high-density polyethylene (HDPE) is used in some trash bags.

References

• Polymer Science Learning Center: How Does the Extrusion Process Work?
• Thomas Net: Plastic Extrusion Process
• Market Publishers: US Demand for Extruded Plastics Projected to Grow to 34 bln lbs in 2013