The plastic extrusion process is something most people know very little about; myself included up until a few weeks ago! I have learned so much about the process and it's history, I had no idea what I was in for. It is actually quite shocking the number of things that we use every day which are products of the plastic extrusion process. Decades of work have gone into increasing the quality and quantity of things that we buy at often extremely reasonable prices, for extreme benefits. Take hurricane shutters, for example, or wire insulation. Things as widely used as adhesive tape are the products of inventive thinkers and doers! So, what exactly is polymer injection molding, and how does it work?

Plastic extrusion refers to the process that thermosetting plastics and thermoplastics go through in order to become products that consumers shop for every day. These plastics are melted, shaped, and molded into one continuous profile. These are cut into desired lengths, depending on the length specified by one of the engineers in charge of working the machine. This is how literally thousands of products are made every day, even something as essential to some places as hurricane shutters!

First, manufacturers have to buy mass quantities of raw plastic in the form of small beads, mostly referred to by specialists as resin. Most producers mix in different dyes or colorants into the mix before the process begins. This adds to the attraction and can even allow for a greater number of customers! Often times, UV ray inhibitors are also added to the resin, for an even wider array of uses.

The resin, after being manipulated, is placed into a plastic extrusion machine, this is usually done with a large truck that is able to lift it into a barrel-like piece of the machine. Once the plastic reaches this barrel, it drops in through an opening in the barrel to a screw mechanism. The industrial screw rotates at a surprising rate, forcing the resin back through the extruder cavity.

Once inside the extruder cavity, the plastic is heated to a very high temperature, generally about 400 degrees Fahrenheit or 200 degrees Celsius. This temperature is required to melt the plastic material. There are sometimes up to three heaters that are on a timed, temperature-increasing system all working together to heat the extruder cavity. Three heaters are used when the plastic extruder is very large, because the risk of overheating decreases.

There are other things that have been added to the complexity of the plastic extrusion machine in order to keep it from getting overheated. If, for instance, the temperature exceeds the one that the machine was previously set to, the heaters are shut off and cooling fans turned on. Instead of reducing the heat so much that it ruins the product still, the plastic maintains the average heat by force and pressure. Talk about having all areas covered!

After the heating process, the injection molded parts enter a series of parallel screens, held together by a puck-like piece of steel. These screens serve the purpose of filtering the plastic liquid in order to remove any contaminants or faults in it. This makes our plastic products sleeker, more durable, and all around more attractive. Once it passes through these screens, it enters the part of the machine called the die.

The final step, and arguably the most important one at that, is the the cooling process. This is where plastic manufacturing companies rely on trained specialists to pay careful attention to how the hot, now completely formed, plastic products are cooled. The most common way of cooling the plastic is by placing it into a sort of tub referred to as a sealed-water bath. Sometimes, when making plastic sheeting or other thin plastic materials, companies use cooling rolls instead.