In reading news and other content about various thermoforming processes, companies, and materials, one thing that has come up many times is the process of plastics extrusion. While most of us know what extrusion is and why that benefits a thermoforming, it doesn’t hurt to have a deeper understanding. Plastics extrusion is a high volume manufacturing process in which raw plastic material is melted and formed into a continuous profile. This makes the rolls or sheets of plastics used for thermoforming consistent and durable for packaging products. The extrusion process is capable of producing items like pipe or tubing, weather stripping, fence, deck railing, window frames, plastic films and sheet, thermoplastic coatings, and wire insulation.
The whole thing starts with raw thermoplastic material in the form of small beads, aka resin. The resin is then gravity fed into the barrel of the extruder. If there are additives, they would be used before this point. The material enters through the feed throat and comes into contact with a rotating screw that forces the plastic beads into the heated barrel (heated to melting temperature). Plastic beads melt gradually as they push through the barrel, if the material overheats, the polymer degrades. The melted plastic will them travel through a screen to remove unwanted particles such as contaminants. Finally, the molten plastic will enter the die. The die gives the final product its shape, and it is imperative the flow is steady- if not, the product will be made with unwanted stresses that cause a warping effect upon cooling. The product then needs to be cooled, and in our case we need plastic sheeting so the material would be cooled by being pulled through cooling rolls.
There you have it- a thorough explanation of the extrusion process. Extrusion is the very first step in creating custom thermoformed products. If you think about it, it can be considered the most crucial. The integrity of a clamshell or blister package lies heavily in the plastic that was used to make it- if the extrusion process was done right, the plastic should be consistent and durable.