The preliminary test results indicate that the material properties are equal to or may exceed those of comparable prints with fresh powder.
As you may guess, with SLS 3D printing, unprinted PA12 powder loses its ability to be reused due to high-temperature exposure in the build area, which causes the polyamide chains to lengthen after condensation, negatively affecting powder flowability and melt viscosity.
This makes the material difficult to process again via laser-based technologies, as the energy input from lasers is too short to process longer molecule chains accordingly. Therefore, comparably high powder refresh rates are necessary, accumulating waste and associated high disposal costs.
A collaborative study conducted by 3D printer manufacturer voxeljet AG, material producer Dressler Group GmbH, and research institute Fraunhofer IPA, reveals that PA12 waste powder can be processed effectively using ink- and printhead-based High-Speed Sintering (HSS) technology.
Due to its ability to deliver selective and thermally gentler energy input, allowing the polyamide to sinter gradually, voxeljet’s VX200 HSS platform facilitates the reuse of this powder.
“The VX200 HSS technology is an open-source system, allowing us to quickly change and adapt process parameters to any powder,” says Jan Kemnitzer, Research Team Lead at Fraunhofer IPA, and adds “We were therefore able to quickly adapt the 3D printer to the material with consistent or improved results in part properties.”
However, before the testing of the recycled powder on voxeljet’s 3D printer, the experts from Dressler processed the used PA12 powder to homogenize and recover key powder properties such as flowability and moisture.
“The results of this study are especially interesting for ink and printhead-based technologies such as the HSS technology. The future possibility of processing this recycled powder on production platforms like the VX1000HSS will bring immense cost savings,” says Tobias Grün, Global Product Management at voxeljet. “Typically, 50 % of the running costs are attributable to powder costs. Thus, this development has a huge effect on cost-effectiveness while boosting circular material flow and reducing waste.”
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