Injection Moulding How to maximise post-consumer recycled content in plastics production
Sustainability is not only driven by government regulations, but consumer demand and environmental awareness around the globe is driving more companies towards sustainable applications. Mold-Masters offers injection moulding solutions for both bio-resins and PCR.
Utilising their co-injection multi-layer technology, Mold-Masters has the ability to combine two separate resins into a single 3-layer melt flow. This enables the company to inject high PCR content as the core layer up to 50 percent of total part weight without sacrificing part quality or cycle time. In their most recent production application, Mold-Masters implemented a 2-cavity Co-injection system for producing 5 gal. (20 L) pails. Each of these 700 g pails incorporated 50 percent PCR as the core layer. According to the company, this solution has the potential to generate significant savings for the moulder (based on current prices) by reducing the use of virgin material and TiO2 (compared to traditional mono-layer pails). These savings and favorable ROI would mean that sustainability initiatives can also make good financial sense, Mold-Masters argues.
The company first introduced this capability as part of its advanced co-injection technology back in 2015. Mold-Masters claims to have leading-edge control, which allows them to precisely control distribution and thickness of the core layer. This is what allows the company to inject a higher percentage of PCR content than competitive systems. Many competing systems would be limited to incorporating up to 35 percent which could limit sustainability targets and could significantly affect implementation ROI, the manufacturer of hot runners and injection mould solutions continues, adding that uniform control allows them to achieve more consistent and fuller core fill and that their patented “fold-over” capabilities would provide a technical advantage that enables them to achieve the highest core percentage. This in turn allowed them to ensure uniform distribution and complete coverage of PCR resins (prevents contact of PCR with product).
Another significant difference pointed out by the manufacturer is the ability to position the core randomly. For example, on packaging applications customers may prefer to keep any PCR A picture containing text Description automatically generated core away from the injection point to avoid moulded in stresses which can cause brittleness and result in drop test failures.
The co-injection technology doesn't cause any penalty to cycle time and existing tooling can be re-used. A variety of materials can be combined although those with similar melt temperatures are ideal for compatibility. Many applications are those that utilise the same material (ex: 50 percent virgin HDPE, 50 percent PCR HDPE). The thermally isolated manifolds from Mold-Masters make it possible to combine two thermally different resins.