It's always important to know the ins and outs of every difficult process right? To me mostly yes, but the other day my friend was talking about what he learned about in his college class, something by the name of polymer injection molding. Interested to learn more on a college worthy topic I listened to his brief description. I was fascinated by how many simple things can be made out of plastic, things I never took a second to think was plastic! I learned that Plastic extrusion is a manufacturing process when plastic is put into a large heater, melted, shaped, and cut to length. As I was eager to learn a little more I did some research and asked a couple people their knowledge on plastic extrusion. The results were a lot of people had mixed reactions on knowing what it was or not!

The actual extrusion process is a simple one, raw plastic is fed into a heated extruder cavity of cylinder. The plastic was in small bead forms, beads that reminded me of the painful days as a child with my plastic pellet gun.

Usually the beads are mixed with colorants before the extrusion process begins. In some plastic extrusion processes UV inhibitors are mixed in as well. Once actually inside the machine, the beads are pushed through an opening in the extruder cavity towards a screw like mechanism. The screw rotates forcing the plastic material through.

Inside the heater the temperature reaches about 400 degrees in order to match the melting point of the plastic beads. Overheating tends to be a problem, so three separate heaters are used in the process the gradually increase the heat inside of the cavity.

This piece of information the program explained was how sometimes the friction and pressure serve their own heat separate from the heaters. It was particularly interesting how the heat built up from the pressure can exceed the heat from the heaters causing the heaters to not be necessary and shut off. Then as the plastic comes out a molten lava like material it moves into a die.

After the high temperatures cooling fans are also employed frequently, helping to keep the plastic extrusion cavity at the desired temperature. Now it's time for the plastic to go into a die. The die gives the plastic its profile after the die, the plastic must be cooled again.

The dye is responsible for giving the plastic its profile in this Plastic Manufacturing process. The hot plastic must be cooled after the bath of dye, so it gets placed into a sealed water bath. Cooling rolls are set out for plastic sheeting and delicate plastic products instead of the fans.

Who knew that one trip to a job fair would turn me into a Plastic Extrusion expert. It's interesting that Window Shutters are developed from the extruding process. After the cooling process it's spooled, coiled or cut to length. Sometimes food and clays are extruded from certain types of plastic.