Interesting news from Voxeljet: they’ve found a way to reuse waste SLS powder.
Waste is a massive issue with the SLS 3D printing process, where thermoplastic powder is selectively sintered by a moving laser beam. The problem is that while in the build chamber, powder is exposed to higher temperatures that modify its properties. This makes it largely unsuitable for re-use in subsequent SLS print jobs.
The answer is to mix in some fresh powder, with different ratios for each model of equipment. However, there always ends up being a huge pile of waste powder from SLS activities. Typically, this is thrown away.
Voxeljet worked with several research organizations to determine ways to potentially re-use waste PA12 powder from SLS sites in their HSS 3D printing process.
A quick recap of HSS: it’s a powder process in which a flat layer of plastic powder is laid down in the usual manner. A toolhead selectively jets liquid binder droplets onto the powder surface.
Now the interesting part happens: the binder is designed to be highly sensitive to infrared light. When a layer is jetted, an infrared light source blasts the surface, whereupon the binder heats up. The heat is sufficient to melt the powder to which it was applied, fusing the plastic powder into a solid layer and binding it to those underneath.
Normally, HSS uses fresh thermoplastic powder, but the research tested whether waste SLS powder could be used instead. What happened? Voxeljet explains:
“The initial results demonstrate that reconfigured PA12 waste powder can be processed effectively using ink – and printhead-based High Speed Sintering (HSS) technology enabling sustainable and cost-efficient production . The preliminary test results indicate that the material properties are equal or may even exceed those of comparable prints with fresh powder.”
They developed print parameters for use on Voxeljet’s VX200 HSS system, which has the ability to use open materials. This makes it straightforward to tune it for a different material such as waste SLS PA12 powder.
This is quite interesting, as it enables the re-use of SLS waste powder by companies operating that style of 3D printer. They could instead ship waste powder to HSS facilities, and possibly even make some money in the process.
For HSS operations, it could also save money because the waste powder will surely be less expensive than fresh powder.
Coincidentally, Stratasys recently announced a similar capability for their SAF system, which is somewhat similar to HSS. It seems that waste SLS powder could soon be a thing of the past, as there will be an increasing number of HSS and SAF operations that could consume it.
Via voxeljet
