Is injection molding environmentally friendly?

Close up of tooling element of injection molding machinery

Read time: 9 minutes | Published on: 20 March 2023

Insights

Injection molded plastic components are widely used by many businesses and industries. As these organizations look to improve their environmental, social, and corporate governance (ESG), they want to make sure every part of their supply chain, production processes and products is as sustainable as possible.

As such, injection molding manufacturers need to do the same. Whether it's reducing their carbon footprint, using renewable raw materials or implementing a closed-loop control system, injection molders are already taking action to make their businesses greener.

This article will answer the question 'is injection molding sustainable?' and explain how to choose and use plastic components without affecting your ESG.

Is injection molding bad for the environment?

Injection molding faces two main environmental challenges - the efficiency of its process and the impact of its materials. Invented back in the late 1800s, the original production process wasn't made with environmental impact in mind. As a result, many manufacturers have faced criticism for their green credentials.

Specifically, the amount of energy used in the manufacturing process, the impact of creating virgin plastics from fossil fuels and the disposal of single-use products into landfill are the main sustainable challenges for plastic injection molding. As part of the manufacturing industry, injection molding businesses also contribute towards 20% of the world's carbon emissions thanks to hydraulic oil- and energy-guzzling machines which are being phased out and replaced with electric machines.

Is injection molding good for the environment?

Injection molding isn't all bad for the environment. In comparison to other molding processes, it is more energy-efficient and produces less waste.

In fully optimized injection molding processes, only the amount of polymer required to fill the mold is used, meaning as little as possible is wasted. Modern electric injection molding machines are also more energy efficient than the original models, meaning they use less power and have less carbon impact.

The new Demag machines from Sumitomo, for example, show increased capacity and reduced energy consumption. A trial in the UK showed a 32% energy saving was gained without adjusting any of the process steps. Whereas it previously consumed 6.31KWh at an average equivalent cost of $0.096 p/h, the trials showed the new machine – the IntElect –saw consumption drop to 4.3KWh (note cost per unit is different in the US).

Added to this, when the process was slightly optimized and the cycle time was reduced by 1.10 seconds, the energy savings and test data stayed consistent. But, by raising the cycling rate, the component yield went up.

At Essentra Components, where these machines are being introduced globally, the potential for savings all-round are impressive. Global Programme Director Chris Butler noted that they would only need to potentially install, run and maintain 100 fewer injection molding machines if replacing hydraulic with a like-for-like all-electric precision machine in order to maintain current run volumes.

Many manufacturers are looking to improve the sustainability of their production process and plastic products by integrating new innovations and technologies into their manufacturing processes.

So, if you're looking for the answer to the question 'is injection molding environmentally friendly?' then you'll be pleased to know that manufacturers are working hard to make the process and products as sustainable as possible.

How can the injection molding production process be made greener?

The starting point for many injection molding manufacturers when it comes to making their operations greener is their production process. This is because injection molding is highly energy intensive and therefore can leave a significant carbon footprint.

To counteract this, manufacturers are focusing on upgrading their legacy machinery, making their process use energy and materials as efficiently as possible.

Switching to electric machines

Until the late 20th century, injection molding machines were powered by hydraulics. As well as using oil, which is a fossil fuel, hydraulic machines wasted lots of energy during production. In contrast, electric machines enable parameters to be tightly controlled, making the process and energy use highly efficient.

By upgrading their legacy machinery to electric options, manufacturers can save up to 60% of energy during production. Although this is a significant upfront investment for businesses, making this change won't just reduce their carbon footprint but reduce their electricity bills and cut down on operational costs too.

Focusing on energy efficiency

Plastic injection molding uses large amounts of energy to create plastic components. This is because the process heats up the polymer to very high temperatures and injects it into the mold under extreme pressure. Depending on the type of plastic and mold being used, different temperatures and pressures will need to be used.

Experienced injection molders are specialists in optimizing these parameters. This optimization means they don't use any energy unnecessarily, maximizing efficiency as much as possible. When combined with modern electric machines, manufacturers can have tight control over process parameters, leading to a higher quality product and better energy efficiency.

Using the latest technology also helps manufacturers create a highly efficient process. Leading manufacturers are using innovations such as big data, Internet of Things (IoT) and smart machines to have greater visibility and control over their energy usage. They also innovate in simple yet effective ways, such as using heat jackets on the extrusion barrels of their machines. For Essentra Components, this cut energy usage by 15%, leading to a significant reduction in carbon emissions.

Minimize material waste

Having an inefficient process doesn't just waste energy, but polymer materials too. For example, if the temperature of the plastic is set too high, it will fall out of the mold. Alternatively, if the injection pressure is too high, this will cause the polymer to burn or burst in the mold.

By optimizing the volume, temperature and injection pressure of the polymer, manufacturers make sure there are no faults in the final product and that none of the virgin plastic is wasted. Choosing or developing the right mold design also means, where possible, there will be no flash (excess plastic) or sprues which need to be removed and disposed of.

This, alongside an effective recycling program, will reduce the amount of waste material going to landfill from factories.

How can manufacturers reduce the environmental impact of plastic components?

Alongside the process, injection molding manufacturers also need to reduce the impact of the plastics they use to create the final components. Now, much of the plastics industry, including injection molders, is working hard to reduce this impact through polymer innovation, recycling and environmentally conscious disposal.

Using more sustainable plastics

Finding green alternatives to traditional polymers has become a high priority for plastics scientists. This is because producing, using and disposing of polymers has a significant impact on the environment.

Firstly, plastics are made from refining fossil fuels. Whether it's oil, gas or petrol, all these source materials need to be mined or extracted, causing significant damage to habitats and releasing various greenhouse gases.

Secondly, virgin plastic production uses a highly energy-intensive, carbon-producing process. Finally, when a plastic product is disposed of at the end of its life, this takes up space in landfill for hundreds of years and releases toxins into soil and water.

As a result, the plastics industry has started to develop alternative, environmentally friendly materials such as:

Bioplastics: materials made from sustainable, renewable raw materials such as sugar cane, vegetable oils or other food waste.
Biodegradable: materials that can be broken down by naturally occurring microorganisms.
Compostable: plastics that break down into natural substances such as water and biomass.

When producing these plastics, it's important that the material characteristics required for components such as durability, flexibility and tensile strength are balanced with their environmental impact. Otherwise, the final components won't fulfill their function and therefore won't be chosen over the original plastic products.

Using recycled plastic content

To reduce the need for more virgin polymers to be made, more manufacturers are looking at using recycled plastics to create their products. This works by taking waste plastic from the end of the process, remelting it and mixing it with virgin polymer at a ratio that allows the material to retain its desired material characteristics.

For example, low-density polyethylene (LDPE) is refined from pressurized ethylene gas sourced from natural gas or crude oil. Rather than using virgin materials to create all of its components, Essentra Components is now using 98% recycled LDPE to make a number of products within its LDPE range with the remaining 2% being colorant. Using recycled plastics helps to reduce new material costs and significantly decreases the carbon footprint of these components.

Considering end-of-life processes

Alongside making the production of plastic components as environmentally friendly as possible, responsible manufacturers also need to consider the end-of-life disposal of their products. This is particularly important for single-use components which can end up in landfill or part of the natural environment if thrown away.

As well as focusing on creating products that are as high quality and long-lasting as possible, manufacturers need to work directly with their customers to come up with appropriate disposal solutions that minimize environmental impact.

What is closed-loop recycling in injection molding?

Closed-loop recycling is a method of disposing of a used product by turning it into a new one. It's called closed-loop recycling because it connects the cycle of production and re-usage together, so no waste products are disposed of in landfill.

The opposite of closed-loop recycling is an open-loop process, which is where recycled materials are mixed with virgin ones to make new products or where none of the materials can be reused.

For injection molders that make plastic components, closed-loop recycling is an effective and sustainable end-of-life disposal method that turns recycled plastics into new products.

For example, Essentra Components has worked with rigid tube manufacturer Iracroft by using LDPE products which can be easily recycled and remade into other components. This has saved 2.5 million parts from going to landfill, reducing carbon impact for both companies.

How are injection molders decarbonizing?

Injection molders are part of the manufacturing industry. In the US, White House Office has announced its Science and Technology Policy which includes a new Initiative for Interdisciplinary Industrial Decarbonization Research. This together with the Bipartisan Infrastructure Law will ultimately see climate pollution reduced in industrial facilities.

Alongside upgrading to electric machinery and making their process as energy efficient as possible, injection molders are decarbonizing by:

Prioritizing energy efficiency in their offices as well as their factories, such as by starting employee initiatives and switching to LED lighting.
Minimizing business-wide waste by installing recycling bins, tracking materials and assets across the production line and making steps to become part of the circular economy.
Choosing renewable energy sources for their electrical power such as providers that use wind or solar farms.
Setting ambitious environmental targets for carbon emissions reduction, waste disposal and energy efficiency.
Choosing green distribution options to send products to customers. For example, distributing products themselves and tracking emissions under their legislative commitments.

By taking these steps as part of a wider environmental strategy, injection molders can significantly reduce their carbon emissions and contribute towards making the industrial sector more sustainable.

Why are injection molders working to be more sustainable?

Manufacturers who use injection molding machines have found that taking a more sustainable approach brings business as well as environmental benefits. By working to become more sustainable, these manufacturers can improve the efficiency of their manufacturing process, reduce their operational costs and integrate innovations that make them more resilient for the future.

Improving efficiencies and adopting new technologies is key to achieving net zero carbon emissions. Essentra Components aims to have all its sites certified Zero Waste To Landfill by 2030 and is working to divert at least 99% of all business waste from landfill, choosing more sustainable disposal methods alongside implementing the waste hierarchy. This is part of its goal of making direct operations net zero by 2040.

Plus, as more customers and governments become focused on making their supply chain greener, making these improvements gives manufacturers a significant competitive advantage and keeps them ahead of strict environmental legislation.

How do you identify a sustainable plastic injection molding partner?

To find an injection molding partner with a sustainable manufacturing process that can meet your product needs, you need to ask the following questions:

What type of machinery are they using? Electric machines are the most efficient, so the manufacturer you choose should have a replacement strategy in place for any hydraulic machines.
Are they using recycled plastics as part of a closed-loop process? This includes recycling waste plastic or old products into new components.
Are they measuring environmental metrics? This may include carbon emissions, waste, and energy consumption data they report to the government or environmental charities.
Are they making energy efficiencies? This should apply across their whole operations, (such as offices and distribution sites) not just their factories.
What green innovations are they introducing? New technologies, polymer types and bespoke solutions should all be considered.
How are they reducing waste? Whether they're aiming to reach Zero Waste to Landfill or are the signatory of a sector-wide initiative, they should be minimizing waste across their business.
How do they match up to legislative standards? Businesses now must meet strict rules set by their governments, so it's key you check if the manufacturer is doing so.
Are they part of the circular economy? This is the process of reusing and recycling materials as much as possible until they can no longer do so.
Do they have ambitious environmental objectives? Sustainability should be a business-wide aim if the manufacturer is to make a real impact.

After getting answers to these questions and checking they can provide the quality products you need, you can make your final decision on which injection molding manufacturer is best for you.