Take a look at that plastic shampoo bottle, milk jug, or laundry soap container. In many circumstances, these everyday household items are made from recycled plastic. Have you ever wondered about the manufacturing process necessary to shape the plastic into a specific shape? At KW Plastics in Troy, AL and Bakersfield, CA we are the world’s largest plastic recycling company, and we know a thing or two about the production process of recycled plastic. In today’s article, we’ll take a closer look at three different types of manufacturing processes for recycled plastic material. Read on to learn more!

Extrusion Method

Have you ever seen decking or fencing made from plastic lumber? How about a park bench, or even sturdy playground equipment? In a prior article, we discussed the sustainable and durable properties of recycled plastic lumber. This amazing building and landscaping material can be made from a mix of blended polymers, polyethylene (PE), and high-density polyethylene (HDPE) resins by using an extrusion process.

With the extrusion process, plastic resins are fed through a hopper down into the barrel of an extruder. While the plastic resin is passing through the barrel, it is gradually heated to the desired melting point for the specific application. Care must be taken not to overheat the resin — overheating the resin can result in degradation of the polymer. After leaving the barrel, the melted plastic resin is usually filtered through a screen to reduce any stray impurities. It is then routed into the die, which is what shapes the melted plastic into its final shape. Precision and consistency is key in this step as any variance can result in uneven product densities. Finally, the extruded plastic is carefully cooled in a vacuum-controlled cooling bath.

There are many products that can be manufactured using the extrusion method, such as plastic sheeting, pipes, and even small wire coatings. KW Plastics offers a large variety of HDPE and MDPE resins and pellets that are suitable for your extrusion manufacturing applications. To learn more, contact our sales department today!

Injection Molding

While extrusion is a type of plastic resin molding, there is a significant difference between extrusion manufacturing methods and injection molding applications. As we just learned, extrusion is a continuous process in which the melted plastic resin is fed through a die. With the injection molding process, plastic pellets are fed into a hopper and then routed into a heated barrel to melt the plastic to the desired temperature. Once the desired melting point has been achieved, the liquid plastic is injected into a mold where it is left to cool. These molds are typically made by an outside manufacturer from steel or aluminum and machined to match the precise specifications detailed by the plastics recycling company or other manufacturer. Once cooled, the molding opens and releases the manufactured product.

Along with the extrusion method, the injection molding method is one of the most widely used processes for manufacturing plastic goods. This is because the process for injection molding is extremely efficient and cost-effective. Large amounts of products can be produced with this method in a very small amount of time, and each product will have identical specifications. This type of manufacturing process is ideal for things like Frisbees®, car bumper covers, and trash cans.

In addition to HDPE and MDPE for extrusion manufacturing processes, KW Plastics also sells a variety of polypropylene (PP) resins ideal for injection molding applications. Contact us today to request a quote!

Blow Molding

In addition to the extrusion and injection molding methods, many items made from recycled plastics are made using the blow molding method. As the name suggests, blow molding utilizes varying degrees of air pressure to create singular plastic items that are hollow with thin walls. It is very similar to the process of glassblowing. The blow moulding method can be broken down into two different types of processes: extrusion blow molding and injection blow molding.

Extrusion blow molding combines the processes of extrusion molding with blow molding in that the initial molten plastic tube is extruded into a mold from the top. At the bottom of the mold there is a pin which blows air into the melted plastic tube to form the plastic to the mold. This process is ideal for high-production products, such as making plastic bottles.

Injection blow molding is slightly different. Here, the melted plastic resin is injected into an injection mold that has a blowing rod in the center of it. This injection mold is then transferred into a blow mold where air is allowed to enter the blowing rod. With this air flow, the plastic resin is essentially inflated to meet the walls of the mold and for the desired shape of the product. This process is not nearly as efficient as extrusion blow molding, and therefore, is not used as frequently.

If your production process relies on blow molding, either extrusion or injection, be sure to contact the KW Plastics sales company to learn more about which HDPE and MDPE plastics are best-suited for your manufacturing application.

Regardless of what manufacturing process you choose, you can count on KW Plastics to be the plastic recycling company capable of providing the high-quality resins you need for your product. We gladly offer custom resin solutions including impact modification, mineral reinforcement, and color and UV stability additives. All resins produced in our recycling plants go through a rigorous quality-control process and we are an ISO-9001:2008 registered facility.

Contact us today or fill out the form below to request a quote today. We look forward to working with you!


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