Sustainability of Additive Manufacturing
Is AM more sustainable compared to traditional manufacturing?
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Additive Manufacturing is often labeled as a more sustainable manufacturing solution compared to traditional methods like milling or casting. However, the question of whether AM is truly more sustainable is still debated and depends on a variety of factors. In this blog post, we explore key insights on the sustainability of AM and its environmental impact.
What you will find in this section
AM technologies are not automatically the most sustainable
While Additive Manufacturing has gained attention for its potential sustainability benefits, it’s important to note that AM technologies are not inherently more sustainable than conventional manufacturing methods. When compared to near-net-shape technologies like milling or casting, AM may have a similar or even smaller CO2 footprint, depending on the application and production process.
The example on the right compares CO2 emissions for producing an aluminum component using Laser Powder Bed Fusion, Milling, and Sand Casting. The left bar represents production with a 60-micron layer thickness and a 400-watt laser, where CO2 emissions per part are higher than those of milling and sand casting. However, by using a 1 kW laser and a 90-micron layer, the printing time and CO2 footprint are significantly reduced. Despite this, sand casting remains the most environmentally friendly option.
Besides printing parameters, other factors such as production batch size, alloy group and the part design have a big influence on the CO2 emissions.
The Role of Regional Energy Mix in the CO2 Footprint
The regional energy mix where a part is produced has a large influence on its overall CO2 footprint, especially for metals like aluminum and steel alloys. AM processes powered by renewable energy sources, such as solar or wind, can significantly reduce the carbon impact. This makes local AM production, using renewable energy, a key strategy for improving sustainability in certain regions.
The most significant factor influencing the sustainability of AM, particularly for metals like titanium, is the energy used in the raw material production process. Using renewable energy in the production of materials has the largest impact on reducing the overall CO2 footprint. In addition, the development of new technologies that allow for the recycling of raw materials or the use of 100% recycled powder will further reduce the environmental impact of AM production.
The left comparison shows how the energy mix influences the CO2 footprint. Using “zero-emission” energy for LB-PBF (Laser Beam Powder Bed Fusion) can reduce the CO2 footprint of aluminum parts by nearly 50%. The primary factor influencing the CO2 footprint is the embedded energy in the raw material. The difference in CO2 emissions between LB-PBF and casting processes is primarily driven by the recycling rate in casting, compared to the support and powder waste generated in AM processes.
In-Use Efficiency Savings Can Outweigh Production Emissions
While AM production itself can involve some carbon emissions, the in-use savings from weight or efficiency-optimized AM designs can far exceed these emissions. For example, lighter parts can improve fuel efficiency in transportation, and more efficient parts can lead to energy savings in manufacturing. These in-use benefits often have a larger environmental impact than the emissions generated during production, though the savings are highly dependent on the application.
How Weight-Optimized AM Designs Reduce CO2 Emissions
One of the significant sustainability advantages of AM lies in its ability to produce weight-optimized parts. These designs reduce the amount of raw material used, which in turn lowers the embedded CO2 emissions in the material. Moreover, because AM often requires less energy in the production process compared to traditional methods, the overall CO2 emissions from part production can be significantly reduced.
The example on the left illustrates the potential in-use savings of an aerospace aluminum bracket. The chart compares CO2 emissions from the conventional design, which are higher than those from the current milling process. This difference primarily results from greater CO2 emissions during powder production.
The right chart presents a theoretical calculation of in-use savings for a bracket with 50% reduced weight. For this example, it is assumed that each kilogram of weight saved equates to 2,500 liters of kerosene annually, and the aircraft’s lifetime is 20 years. While CO2 emissions from material production are already reduced, the most significant savings come from a 43-ton reduction in CO2 emissions over the aircraft’s lifetime. Although the exact values in this example may vary, it clearly demonstrates the substantial potential for in-use savings.
Conclusion: The Future of Sustainable AM
Additive Manufacturing holds great promise for a more sustainable future, but it is not a one-size-fits-all solution. The sustainability of AM depends on factors such as material optimization, energy sources, and production techniques. While AM offers significant environmental benefits, especially when used with renewable energy and optimized designs, it’s essential to consider each case individually to determine the overall environmental impact.
How to use AM in the most sustainable way?
Determining whether Additive Manufacturing is more or less sustainable for a specific component can be challenging and may lead to detailed discussions. However, there are several ways designers can positively influence sustainability in AM:
- Part Identification: Focus on components where AM can significantly reduce the carbon footprint.
- Design Optimization: Redesign parts to maximize AM benefits, such as:
- Lightweighting airplane components
- Improving motor efficiency
- Extending tool lifespan
- Repair: Consider using AM for component repairs to extend their lifespan and reduce waste.
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