EVERGREEN – Energy-Efficient Design of the Laser Beam Melting Process Chain by a Reduction of the Embodied Energy

The EVERGREEN research project is dedicated to the comprehensive analysis and improvement of the process chain of powder bed fusion of metals using a laser beam (PBF-LB/M). The aim is to create sustainable strategies to reduce material losses, increase the resource efficiency, and improve the process reliability. The work is aimed at reducing the embodied energy associated with the production and processing of metal powder and the disposal of process by-products.

Initial situation

Additive manufacturing processes are regarded as forward-looking technologies with a high resource efficiency. The PBF-LB/M process in particular offers great potential due to its low material usage, the reusability of powder materials, and the geometric flexibility. However, inefficiencies along the process chain lead to a high proportion of embodied energy in the end product. In addition to the cost- and energy-intensive manufacturing process of the metal powder, considerable material losses also occur during fractionation, in the manufacturing process itself, and during disposal. At the same time, there are safety-related challenges in handling metallic powders and the resulting filter residues. The current practice of disposing of potentially recyclable materials as hazardous waste is neither economically nor ecologically sustainable.

Objective and expected results

The EVERGREEN project aims to make the PBF-LB/M process holistically more sustainable, productive, and safe. The focus is on three overarching fields of action:

• Reduction of the embodied energy along the entire process chain,

• increasing the productivity of the PBF-LB/M process through targeted process adjustments,

• reducing the volume of waste and improving occupational safety during the powder processing and disposal.

A key objective is to increase the degree of powder utilization by processing “as-atomized” powder with a broad particle size distribution, which has so far remained largely unused. To this end, the process chain is being redesigned – from powder feeding to powder recoating and component exposure. A disposal concept is being designed for non-recyclable powder fractions and filter residues, taking into account safety-related aspects. The ecological evaluation of the process chain is carried out by means of a life cycle analysis.

Approach

To begin with, existing process losses are systematically recorded and quantified. The focus is particularly on the areas of powder production, fractionation, application process, exposure strategy, and recycling and reconditioning. Process adjustments are then conceptualized and experimentally investigated.

A central element is the design of a new process layout for processing “as-atomized” powder, which cannot be used in PBF-LB/M systems due to its properties so far. In addition, strategies for the use of recycled powder and for avoiding critical residues from filter technology are being created.

The technical and ecological effects of the measures are continuously evaluated. The results will be incorporated into a practical guideline for the resource-efficient and safe design of the PBF-LB/M process. Finally, a validation is carried out on an industrial scale.

Acknowledgements

The EVERGREEN research project is funded by the German Federal Ministry for Economic Affairs and Climate Protection (BMWK) as part of the 8th Energy Research Program (funding code: 03EI5032A) and supervised by the Project Management Jülich (PtJ). We would like to thank the sponsor, the project management organization, and the project partners for their dedicated cooperation and technical support in the realization of this forward-looking project.