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Balancing Sustainability, Efficiency, and Innovation in Plastics ProcessingBalancing Sustainability, Efficiency, and Innovation in Plastics Processing
Driven by sustainability, plastics processors increasingly must focus on reducing their environmental impact by managing emissions, using more energy-efficient technology, and adopting responsible material selection methods.
5 Min Read
Adoption of hybrid molding technology can drive a sustainable transformation by optimizing the efficiency of production processes.yoh4nn/iStock via Getty Images
The plastic lifecycle currently emits more than 0.85 gigatons of greenhouse gases. If current plastic production and consumption patterns continue, emissions could reach 1.34 gigatons per year by 2050. Plastic manufacturing methods vary and are used in a range of industries, including automotive, electronic hardware, food and beverage packaging, and medical devices.
Injection molding, which involves injecting melted raw material into a mold, is one of the most popular methods — gas-assisted, micro-injection, and insert molding are the most common types of injection molding. Extrusion and blow molding also are widely used, with extrusion being the most sustainable because it uses material efficiently, produces less waste, and can be optimized for energy consumption.
All of these methods release high amounts of volatile organic compounds (VOCs) and require high temperatures (approximately 200 to 350°C). Maintaining these temperatures requires a significant amount of energy, which contributes to higher greenhouse gas emissions. With increased awareness of sustainability, the focus in plastics processing technologies is shifting toward reducing its environmental impact, managing emissions, and utilizing more energy-efficient methods and sustainable materials.
Assessing sustainability in plastic injection molding
The amount of CO2 emitted during operation varies depending on the type of machine — electric, hydraulic, or hybrid. All-electric machines can generate up to 50% less CO2 than hydraulic presses.
The machine's carbon footprint is also influenced by the kind of product being produced: Small, intricate parts typically require more energy because more precise, slower manufacturing processes are applied, resulting in higher energy consumption per part.
Carbon dioxide emissions vary depending on the process and type of machine.
Wide adoption of hybrid molding technology can drive a sustainable transformation in the industry by optimizing the efficiency of production processes. Hybrid injection molding costs less than electric injection molding but more than hydraulic injection molding. Companies may need to invest in additional training and infrastructure to integrate hybrid systems into their production lines.
Injection molding machines can work with a variety of materials, including thermoplastics, thermosets, and elastomers. This makes injection molding the preferred choice in a variety of industries, including automotive and medical.
Extrusion is used in a variety of applications, including packaging materials, pipes/tubes, and window frames. These finished products are simple to produce and require little energy, making the method relatively sustainable. Finished products are made directly from raw materials with high precision, resulting in lower scrap rates and a smaller environmental impact.
The majority of bio-based plastics are extruded because they are primarily used in packaging. Bottles, containers, and jugs are made using blow molding, which involves inflating melted plastic inside a mold to create hollow objects. It produces goods with little waste, and the majority of the extra material that is left over is recyclable. Because it requires less energy to heat and shape plastic than injection molding, it also generally uses less energy.
Integrating energy-efficient practices
Energy-efficient technologies can be used in molding machines. For example, variable frequency drives (VFDs) can regulate a pump motor's speed to better match output to the amount of hydraulic fluid required. By optimizing motor energy use and increasing energy efficiency, greenhouse-gas emissions and overall power consumption are reduced.
Thermoplastics are widely used in molding processes because they can be melted and re-solidified multiple times without a change in chemical properties. When heated, thermoplastics become extremely flowable and can fill intricate mold cavities. This makes thermoplastics the most suitable for use in molding processes, but they cannot be considered sustainable because most thermoplastics are derived from non-renewable sources such as fossil fuels and have limited recycling potential. Some commonly used thermoplastics are polyethylene (PE), polypropylene (PP), and acrylonitrile butadiene styrene (ABS). The industry is gradually transitioning to more sustainable practices by using biodegradable polymers such as polylactic acid (PLA) and polyhydroxyalkanoates (PHA), which are designed to degrade more quickly and safely in the environment than traditional plastics.
Bio-based plastics are made from renewable resources like corn starch, sugarcane, or cellulose, rather than fossil fuels. They function similarly to traditional plastics while reducing the environmental impact. Biodegradable polymers can be created from bio-based materials, but not all bio-based materials degrade easily or are biodegradable.
Chart shows sustainability attributes and cost comparisons of different plastics processing technologies.
Sustainability across the packaging value chain
A major sustainability shift is happening in the packaging industry. Sustainability efforts have resulted in a significant move away from multi-layer laminates and toward single-layer or monomaterial packaging. Monomaterial designs simplify recycling by using only one type of plastic, making it easier to reprocess while lowering greenhouse-gas emissions.
Amcor and JM Packaging have developed standup pouches for rice that use single-layer plastics, making them easier to recycle compared with multi-layer options. Amcor has heavily invested in developing monomaterial packaging that is easily recyclable as well as integrating recycled materials into its packaging.
Nestlé has been transitioning from multimaterial flexible plastics to monomaterial packaging as a part of its goal to make all packaging recyclable or reusable by 2025.
Unilever has introduced a monomaterial personal care pouch in Japan, which was created by Toppan. The pouch uses a thin vapor-deposited barrier that maintains the necessary product protection while remaining compatible with PET recycling streams.
Thin-wall packaging is also gaining popularity in the industry, as it focuses on using less plastic material while maintaining packaging functionality. It is commonly used for dairy products and frozen foods, and can even replace glass and cans in some cases. Last year, Cosmo Films invested in a new company called Cosmo Plastech, which provides thin-wall packaging sheets and containers. At the same time, Netstal (Switzerland) introduced a lightweight thin-wall cup made entirely of polypropylene.
The use of bioplastics is not new, and it is being widely adopted in a variety of industries, including packaging and consumer goods. However, the transition is slow as it is costlier than traditional plastics and is not as widely available.
Material selection under these conditions involves achieving a balance in performance, cost, and environmental impact. The material must be compatible with the molding process, meet mechanical specifications, and have a low environmental impact. Although traditional thermoplastics provide excellent performance, environmental concerns are pushing the industry toward bioplastic and biodegradable alternatives. These alternatives must provide product quality and functionality without significantly raising costs.
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