You’ve probably seen literature and information concerning the three R’s: Reduce, Recycle, Reuse. In plastic injection molding, utilizing these three concepts can save money on production expenses and create more problems than expected. If you have always thought plastic injection scrap was 100% recyclable, you were close to the mark. It’s usually recyclable, but there are specific strategies to meet the challenges of recycling plastic injection molding scrap efficiently.
Clearing the First Hurdle with Recycling
Recycling materials isn’t a new idea. It is well practiced around the world. The U.S. lags behind other countries that use recycling initiatives though. In 2021 it was estimated that 94% of Americans supported recycling efforts with 74% noting it should be a priority for all materials. That is a lot of support, yet America only recycles 25% of the plastic made in the U.S. Some of the challenge that make recycling plastic so low, which includes plastic injection molding, is the differing materials that must be dealt with. Plastics used for injection molding have various properties and melting points that makes their reuse challenging. It’s not a simple matter of just grinding each material into small pellets and melting them together. Making a contaminated lot of material can cause injection molding machine issues, process changes, and complications with operations just from mixed recycling of materials.
How Do We Recycle Molding Scrap Better?
The first step in the direction of recycling better is with segregation of materials. Molding scrap must be kept separately so that it doesn’t end up as a mixed bin of material. Simple materials such as Polypropylene and Polyethylene Terephthalate (PET) have melting temperatures just 25°F apart, but that doesn’t mean they can easily be recycled together. They also carry individual properties that make their combined recycling a challenge to reuse without changes in machine settings and careful consideration for the product they are molded into.
Beyond plastic characteristics, other factors must be taken into consideration. Foreign materials that find their way into the scrap must be removed. It’s not uncommon to see small bits of metal find their way into the scrap bins, which then are incorporated into the scrap recycled pellets. Small metal pieces won’t melt when the plastic does, and it won’t flow through the injection mold with the plastic. It can cause density changes and voids in molded components, and in rare cases it can completely clog a mold to render it unusable. In the cases of clogged molds, they must be removed from the machine, disassembled to remove the clogged area, and repair any surface damaged that could have been caused. One simple piece of metal can cause thousands of dollars in damage, and also shut down your operations for a short period of time.
One of the last major challenges injection molding faces is the incorporation of post-consumer plastic scrap. Materials kept in the molding facility tend to stay clean without chemical residues or foreign materials lingering from the molding process. In order to increase the plastic recycling average from 25%, post-consumer plastics must be better utilized in the creation of new products. That’s easier said than done. Scrap materials brought back in from consumer recycling efforts can have lingering chemical residues that can stay with the plastics into the new products. These residues can cause molding challenges and mold damage if they are recycled without proper cleaning. Extra cleaning equates to extra investment, and many consumers don’t want to pay for recycling efforts if they cost more for them.
5 Keys to Focus on for Recycling Plastic Scrap
These are key items to increase the use of recycled materials in your new product:
- Research if a recycled plastic is an option for your process and/or future product. Your material choice may not be recyclable, or it may cause too much fluctuation in performance if reused.
- Identify and understand the source of the recycled materials. You need to know where they come from, what they were used for, and how they will affect your process.
- Know what type of materials can be recycled for your products. Material melt points, corrosion resistance, and more characteristics can affect the performance of your products. Don’t introduce recycled materials that will affect your molding process and products.
- Determine how much recycled material can be used before performance suffers. Some scrap materials can be mixed at a rate of 4% with virgin materials without a significant drop in performance or an effect on molding operations. Other materials could be 10%. Determining the proper ratio can reduce cost, increase recycling, and still generate profitable products.
- Use current knowledge to continue generation of new ideas for future products. Recycling technology and engineered resins are continuously improved every year. Use that information to create new ideas and better strategies to use less virgin material and recycle more scrap.
Engineering your product design for increased recycling can be a significant challenge. Some computer software packages include built-in tools to assist designers with recycling predictions, but a significant portion of the industry knowledge comes from years of experience. SEA-LECT Plastics has an elite staff of designers and manufacturing professionals that design and produce world-class products to achieve high levels of recycling. We have the knowledge to make your design simple, cost-effective, and the turn-key assembly options to produce it in-house in Everett, Washington. If you have a new idea, call us (425) 339-0288 or email us at email@example.com. We can offer you advice on the best technology to use, the best materials to meet your product demands, and how to navigate through each development stage with ease.
Matthias Poischbeg was born and raised in Hamburg, Germany. Matt moved to Everett, Wash., after finishing his bachelor’s degree in business in 1995 to work for Sea-Dog Corporation, a manufacturer, and distributor of marine and rigging hardware established in 1923.
In 1999, Matt took over the reins at Sea-Lect Plastics Corporation, a sister company of Sea-Dog and a manufacturer of plastic injection molded products with an in-house tool & die shop. Matthias Poischbeg is also a contributor to Grit Daily.