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MTC's additive manufacturing experts on how AM can develop its sustainability credentials
With sustainability gaining traction, manufacturers are seeking innovative and eco-friendly solutions to reduce environmental impact. Additive Manufacturing (AM) offers an opportunity for sustainable practices to overcome this challenge. The AM industry grew 18% in the last year (Wohlers Associates, 2023) emphasising the need to explore sustainable ways of using the technology. This requires moving towards a circular economy, aiming to eliminate waste through circulating resources and balance environmental, economic, and social factors. This article explores AM’s current state, benefits and challenges in the circular economy context, and provides strategies and opportunities to enable AM as a sustainable manufacturing technology.
BENEFITS
AM’s sustainability advantages over conventional technologies include:
• Material efficiency – Lower buyto-fly ratios and tooling elimination.
• Energy conservation – At the manufacturing stage, thanks to reduced material sourcing and design optimisation, and at the operation stage enabling a more efficient energy or fuel consumption during operation.
• Reduced transport –Distributed manufacturing enables on-site manufacturing, reducing goods and materials movement.
• Life extension – Through highly optimised or customised parts that have the potential to extend product life, and through assembly component repair or replace, reducing waste.
CHALLENGES
While these benefits suggest AM offers greater sustainability, key challenges remain to fully understand its true impact. These include materials, energy consumption, data availability and knowledge-related challenges to make the industry aware of their contribution to a circular economy.
MATERIAL CHALLENGES
The extraction and processing of AM materials contribute to environmental degradation and greenhouse gas emissions. While some polymers are derived from natural sources, most AM materials require mining or are derived from oil. Furthermore, each AM technology has specific material requirements, such as melt flow characteristics, viscosity, and thermal properties, hindering the development of standard sustainable materials for all processes. This diversity limits material scalability and leads to issues around recovery and recycling, where unique material compositions make it challenging for conventional waste streams. An additional challenge is identifying materials, which requires specialised equipment for composition analysis and recovery route definition.
PROCESS CHALLENGES
AM processes require energy for heating, melting, and fusing materials, whilst removing support structures, surface finishing, and applying coatings require additional energy, time, and resources. Capturing and assessing sustainability metrics is more difficult due to continuous part changes. Additionally, energy for one part per build differs compared to multiple, limiting the ability to calculate energy consumption on a component basis.
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While AM shows great potential for smallscale production and customisation, scaling up for mass production remains a challenge. Enhancing AM machine throughput while maintaining quality is necessary to make AM competitive with traditional manufacturing in terms of efficiency, leading to energy reductions.
KNOWLEDGE CHALLENGES
Understanding the environmental impact of AM faces two crucial challenges: data availability and how to use it to validate AM’s sustainability. Databases like Ansys’ Granta are resource pools for materials, however, the differences between AM processes hinder assigning generic data for comparison. The agile nature of AM leads to a varied processing and destination for parts, reducing the data uniformity. The sheer volume of data needed for reliable and accurate product and machine lifecycle assessments continues to be an ongoing challenge in identifying AM’s true environmental impact.
WHAT CAN YOU DO?
As an AM designer, it may feel like there are limited opportunities to impact its sustainability, however, design is understood as a circular economy driver and there are already common design strategies to promote a sustainable mindset. These are some prominent sustainable design strategies and their potential use cases in AM, starting with those that are most effective at reducing environmental impact:
• Design for life extension – Topology optimisation or generative design can enable highly functional parts which can prolong life. Customisation offered by AM can improve desirability and emotive connection, also linked with prolonged life.
• Waste source reduction design –Lattices or topology optimisation can reduce material usage whilst retaining the structural integrity. Part consolidation can reduce material usage and assembly steps.
• Design for material substitution – When options are available, the environmental benefits of different materials should be considered.
Material substitution of high-density materials with low-density materials can reduce energy use in transportation and more efficient operation.
• Modular design – Where there is difference in life span, only defective parts need to be replaced, saving energy and resources compared to remanufacture of the entire component. Distributed manufacture ensures spares are available on demand.
• Design for reusability – Standardising certain aspects of the design may allow for re-use in future products.
• Design for disassembly – Considering how the assembly could be dismantled into individual materials ensures each resource can be recovered at end of life.
• Design for recycling – Recycled and recyclable materials should be considered where possible. Ecolabelling practices should be used to identify materials for easier recycling such as embossing material information or QR codes.
• Design for energy recovery – Materials that give off toxic fumes should be avoided if incineration is the disposal method.
• Design for disposability
– The use of toxic materials should be minimised or eliminated. Consider biodegradable materials which can be composted.
FUTURE MATERIAL
As the technology progresses, it is important to understand how AM can develop its sustainability credentials. Finding alternative materials that are renewable, bio-based, recycled and recyclable is crucial for reducing the environmental impact of AM, however, sustainable materials must also balance these requirements without compromising function. Expanding production and supply chains for sustainable materials and making them economically viable will be essential for their widespread adoption.
There are limited options for recycling AM waste due to poor waste infrastructure, incentives to recover material and material identification issues. Further research is required to establish suitable waste management strategies and develop the infrastructure to recover return to recycled feedstock. There is also currently no standard practice for labelling AM parts, making it difficult to identify and recycle AM materials. Although labelling tools would enable designers to combat this issue as individuals, a more widespread solution would require legislating the use of environmental labelling. Labelling practices could simplify material identification and maintain specific material compositions or alloys through the recycling process as opposed to being mixed with other grades which would prevent them being re-circulated back into AM feedstock. Overcoming these material-related challenges in AM requires collaboration between material scientists, AM technology developers, and industry stakeholders.
PROCESS
To fully understand the sustainability of AM, data needs to be collected and assessed. Life Cycle Analysis is a prominent tool used to assess product or process sustainability therefore it should be more widely used in AM. Widespread and reliable data relating to the environmental impacts of AM materials and processes is needed beyond individual case studies and research to enable the leverage of such tools.
KNOWLEDGE
To improve AM’s sustainability in the future, every stage of the design for AM workflow and its supply chain must engage with the concept of the circular economy. Since the topic of sustainability is still relatively new, it cannot be expected that everyone involved will have prior experience. Therefore, it is important that the necessary education is made available relevant to the role. Training and guidance will help to shape the mentality of the industry and transition it towards a circular economy.
SUMMARY
As a disruptive technology AM has the potential to lead the way in sustainable manufacturing and promotes benefits such as material efficiency, energy conservation, reduced transport, and life extension. However, the challenges, such as the environmental impact of materials used, variable energy consumption, and lack of standardised data for sustainability assessment limit its current potential. Designers can adopt sustainable design strategies to make an immediate impact on their components, however, the future of AM sustainability depends on developing renewable and recyclable materials, establishing effective recycling practices, and promoting education and training in the circular economy for the industry.
References: Wohlers Associates. (2023). Wohlers Report 2023: 3D Printing and Additive Manufacturing Global State of the Industry.
