Plastic products take many different forms – known as plastic profiles to us – but they all start as raw material called resin. In plastic extrusion, resin beads are melted down, filtered for uniform consistency, pushed through a die-cut for the final product shape, and then cooled. It’s a complicated process that takes many forms, but here’s a quick breakdown of how it works.
1. Raw plastic is fed into a hopper – along with any colorants or additives – that feeds down into the extruder.
2. The beads flow from the hopper down through the feed throat, which dispenses them onto a large spinning screw operating within a horizontal barrel.
3. The beads pass through the barrel on the screw while being heated to the melting temperature specific to that type of plastic. By the time it reaches the end of the screw, the plastic is thoroughly mixed and has a consistency like thick bubble gum.
4. At the end of the screw, the extruded plastic flows across a screen and a breaker plate, which serves two functions. The screen removes any contaminants or inconsistencies in the plastic, and the breaker plate changes the motion of the plastic from rotational to longitudinal. Now it’s ready to die.
5. The die for an individual plastic profile is more than just a hollowed-out shape of the final product. It’s designed so that the plastic flows smoothly and evenly from the cylindrical profile of the extruder into the final profile shape.
Consistency in this flow is critical to achieving an end product with integrity.
Plastic extrusion is used to produce a wide range of products on the market today, from building materials to consumer products to industrial parts. Pipes, tubing, window frames, electrical covers, fence, edging, and weather stripping are just a few of the common items made by plastic extrusion, along with thousands of custom profiles.