red solo cup

Extrusion can be thought of as injection molding’s cousin. Injection molding, which we discussed in detail in our last blog post, is a plastics-making process that injects molten material into a mold, where it hardens and produces replicable products. In this blog post, we’ll take a closer look at what is extrusion.

KW Plastics is a company that buys recycled plastics as well as a recycled plastic material manufacturer. Basically, we buy scrap plastic and then we turn that scrap plastic into plastic resin pellets that we then sell to other recycled plastic manufacturers for use in their plastic products. While plastic does take hundreds of years to break down in its natural form, plastic is a great material to reuse many times over. Continue reading to learn more about the extrusion process, and contact us today when you need to sell your plastic scraps!


Extrusion, in general, is a manufacturing process where softened metal or plastic is shaped through a die to form a shape or product. Extrusion comes to us from the Latin “extruder” with “ex” meaning out and “trudere” meaning to push. Basically, the process entails resin pellets, powders, or a solid plastic mass being heated and then forced out through a die into a shape. Extrusion is a continuous process, meaning once it starts, it doesn’t stop until the plastic product is finished. This is the main difference between extrusion and injection molding, which is a discontinuous process that relies heavily upon molds that require pauses to handle.


  1. Plastic material or resin is fed into a hopper that falls into the barrel of the extruder.
  2. In the extruder is either a single or twin screw that forces the resin, resin pellets, powder, or other materials into the barrel that is then heated to the desired melting point.
  3. The heated plastic is usually screened to remove any contaminants and then forced through a die that forms a shape. The molten plastic must flow evenly to prevent warping upon cooling.
  4. This shape is then cooled (usually through a water bath) and then possibly cut and further refined into the finished product through the use of sub-processes (sheet, blown or cast film, profile, pipe, or pelletizing).
  5. Depending on the product, sometimes a secondary extruder is employed to put on finishing touches. For example, in the manufacturing of adhesive tape, this is where the adhesive is added.


You’ll see extrusion at work in the following processes:

  • Plastic drinking cups (think Red Solo Cups)
  • Plastic films used to make grocery bags
  • Saran Wrap
  • Plastic plumbing pipes
  • Plastic siding


KW Plastics began in 1981 with a concern about the amount of plastics building up in our local landfill in Troy, Alabama. Our founders decided to do something about it and began to turn recycle plastics into other products for sale. We expanded by taking used automotive battery casings and turning them into polypropylene (PP) resins. PP resin use began to grow, and KW grew along with the demand for recycled plastic to use in other plastic manufacturing processes.

Today, KW Plastics is the world’s largest plastics recycler, buying plastic scraps and turning them into plastic resin pellets for use in processes such as extrusion. We have over 100 million pounds of silo capacity in order to process over one billion pounds of scrap plastic annually. We are proud of our heritage and of our part in making this world a better place for future generations. Whether you are in need of plastic resin pellets for blow molding, injection molding, extrusion, or blown film, we’ve got you covered. Ask about our delivery service, and contact us today for all your plastic resin pellets needs!