Recycled Plastic Injection Molding

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Mixed blue, green, and clear pellets feeding a molding barrel, with a speckled housing in front of an open mold.

Definition of Recycled Plastic Injection Molding

Recycled plastic injection molding is the molding of parts from recycled resin, either alone or blended with virgin resin at a stated percentage. The recycled content is usually post-consumer recycled (PCR) material, recovered from products that have been used and discarded, or post-industrial recycled (PIR) material, recovered from manufacturing scrap before it reaches a consumer. Most of it is mechanically recycled, meaning the plastic is sorted, washed, melted and pelletized, though chemically recycled feedstock is also available for some polymers. In-house regrind made from a molder's own runners and rejected parts is normally treated separately. Recycled content is specified as a percentage by weight of the part and verified through chain-of-custody certification, such as the Global Recycled Standard (GRS) or UL 2809.

Why This Matters for Your Business

Recycled resin varies more from lot to lot than virgin resin, and that variation shows up in production. Changes in melt flow rate, which measures how easily the melted plastic flows, shift fill and dimensions and mean the molder has to adjust settings more often. Mixed sources give a gray or off-white base color, which limits light and bright colors, and contamination can cause black specks, gels, odor and lower impact strength. These effects raise reject rates and call for closer incoming inspection, both of which add to the piece price.

Price and supply are also less predictable, since high-quality PCR grades often cost as much as or more than virgin resin and supply can be tight, so check lead times for your grade and color before you commit to a launch date. Demand is rising because of regulation, including the EU Packaging and Packaging Waste Regulation, which sets minimum recycled content for plastic packaging from 2030, and because of brand targets in consumer goods and automotive. Taiwan has a mature collection and recycling system, and local compounders supply PCR grades of polypropylene, acrylonitrile butadiene styrene (ABS) and polyethylene terephthalate (PET), which shortens the supply chain for parts molded there for export.

Related Terms

Melt IndexPlastic Material Selection
In many cases it can, provided the recycled material is a compounded grade with a datasheet and controlled specifications, and the part does not work at the limit of the material's properties. Post-industrial material from a single known source often performs close to virgin resin. Post-consumer material is more variable, so blending it with virgin resin is a common way to keep properties within specification while still meeting a recycled content target. The safest route is to mold trial parts from production lots of the actual recycled grade and test them against your drawing and performance requirements, including impact, color and dimensional checks. Washed flake sold without a datasheet is rarely suitable for engineering parts.
Recycled content is verified through documents and audits, because laboratory tests on a finished part cannot reliably measure how much of it is recycled. Under chain-of-custody schemes such as GRS, each company in the supply chain is audited and each shipment carries a transaction certificate. Ask your molder for these certificates, together with batch records showing the blend ratio used for each production lot.
Recycled plastic can be used for food contact only when it comes from a recycling process approved for that purpose, and it is rarely used for medical parts. In the EU, Regulation (EU) 2022/1616 controls recycled plastic for food contact, and in the United States the Food and Drug Administration (FDA) reviews recycling processes and issues letters of no objection. Approved processes exist mainly for PET bottle material, so options for other polymers are limited. Medical device makers generally avoid recycled resin, because biocompatibility testing under ISO 10993 and the material traceability expected under ISO 13485 depend on a consistent, fully documented material.