Sustainable injection moulding: how the industry is becoming more sustainable

The plastics processing industry is facing a major transition, and injection moulders who strategically embrace sustainability are building a long-term competitive advantage.

Material as a starting point

When we talk about sustainability in injection moulding, the focus is almost always on reducing the carbon footprint. The most important step, therefore, is the choice of material. In this regard, you have options such as: reduce, recycle and renew.

‘Reduce’ means taking raw material usage into account in your product design and trying to limit the total weight.

Recycling raw materials is the best way to reduce CO2 emissions if the use of plastics is unavoidable.

In this context, ‘renew’ refers to the use of raw materials from renewable sources, such as bio-based plastics.

Recycled or bio-based plastics

Post-consumer recycled (PCR) and post-industrial recycled (PIR) materials are becoming available for an increasing number of applications in grades comparable to virgin material. Bio-based plastics, made wholly or partly from renewable raw materials, are gaining ground, although their mechanical properties and processing windows are often still more limited than those of conventional materials. The choice of more sustainable raw materials always requires a reassessment of the production process and the specifications of the end product.

• Post-consumer recycled material: available in PA, PP, ABS and various other types of polymer

• Bio-based PLA, PHA and PAs for applications with lower mechanical requirements

• Recycled materials require adjusted process parameters and additional quality control

Energy efficiency in the injection moulding process

Injection moulding is an energy-intensive process: hydraulics, heating and cooling require a constant supply of power. The transition from hydraulic to electric and hybrid injection moulding machines has significantly reduced energy consumption in recent years. Electric machines are 50 to 70 per cent more energy-efficient than conventional hydraulic equivalents. In addition, shorter cycle times, optimised cooling systems and smart production planning systems offer further opportunities to reduce energy consumption per part produced.

Design for Sustainability: the role of product development

Sustainability does not begin at the injection moulding machine, but at the drawing board. Products designed from the outset with an eye to material efficiency, ease of disassembly and recyclability are inherently more sustainable than products that are ‘greened’ retrospectively. Thin-walled constructions, avoiding material combinations that make separation during recycling difficult, and minimising runners and sprues are concrete design choices with a direct environmental impact. Co-creation between the client and the injection moulder at an early stage of product development is the most effective approach to achieving this.

Regulations and customer requirements as drivers of change

European legislation on the circular economy – ranging from future requirements to incorporate a certain percentage of recycled material to the Corporate Sustainability Reporting Directive (CSRD) – is imposing increasingly specific requirements on the use of materials, recyclability and the carbon footprint of products.

Major OEMs then translate these requirements into their supply chain via procurement criteria and product specifications. For injection moulders wishing to operate as strategic partners, anticipating these requirements is not an option but a necessity. Those able to provide sustainability data on material sourcing, energy consumption and CO₂ emissions will have a head start in tomorrow’s tenders.