What is Selective Laser Sintering (SLS)?

Pooria Sohi December 28, 2021 3 min read

Learn all about selective laser sintering (SLS) technology — what it is, who it’s for, and how to use it in conjunction with Autodesk Fusion 360.

Selective laser sintering (SLS) is one of the oldest and most developed additive manufacturing technologies. If you want to rapidly produce reliable, high-fidelity prototypes with the bonus of batch scale, this tech is for you.  
When you hear the term SLS, though, you probably still imagine “fuzzy” parts that leave behind residue and are only available in single colors. However, SLS technology has come a long way in recent years, meaning you can finally leave that image behind. Post processing now enables SLS machines to create polished parts with a high-quality surface finish. Plus, you can pack a lot into an SLS machine’s build volume, making production at all scales easier. 

Image courtesy of Formlabs.

What is selective laser sintering (SLS)? 

SLS machines work from the same root data as most other printing processes. First, your part gets sliced into layers. The layers then build up one by one until the part is complete. Selective laser sintering technology sinters plastic together by tracing each layer slice with a laser. The laser sinters plastic powder together for each layer, then adds powder for the next layer on top, sintering with the layer below in the process. This process happens very rapidly and accurately.

SLS vs. FFF 3D printing

Selective laser sintering and fused filament fabrication (FFF) are plastics-based machines, so what’s the difference? Well, SLS parts are much higher fidelity than their FFF counterparts. Additionally, post-processing with SLS is much easier than FFF (when you have access to a tumbler). FFF requires significantly more time with sanding, priming, and painting to get a presentable prototype, whereas SLS is much more hands-off.  
However, FFF machines are more affordable than selective laser sintering and don’t require the same space to operate. FFF printers also don’t need special post processing equipment, unlike SLS. FFF is not better than SLS, nor is SLS better than FFF. It just depends on what tool suits your needs more.  

Selective laser sintering benefits

As with any technology, selective laser sintering is not perfect. It can be more costly, requires more physical space, and parts can be brittle and weaker than other methods. SLS also has fewer material options than FFF does for printing. However, there are plenty of advantages that make it a worthwhile option to explore.

Selective laser sintering offers a more “set it and forget it” workflow than other additive manufacturing technologies. Once a print finishes, it’s just a matter of brushing off any excess powder (which can be reused) and then tossing it into a tumbler or dedicated post processor. The achieved fidelity is excellent for physical prototypes, visual testing, presentations, and sometimes even stress testing (depending on your manufacturing processes).  
One of the biggest benefits of selective laser sintering is that it does not require support materials, which enables it to pack the build volume up so well. As parts are built, the surrounding powder holds the part in place, eliminating the need for support material. As a result, you can pack your build volume to the brim knowing every part will come out fine and that you will not need to break off support structures. 

Ready to start your SLS 3D printing journey with Autodesk Fusion 360? Good news! We’re adding selective laser sintering capabilities to Fusion 360 very soon. Once again, we’re teaming up with our friends at Formlabs to integrate Fuse 1 capabilities into the product. In the meantime, the Fusion 360 Additive Build Extension unlocks advanced 3D printing features in Fusion 360. Try it for free today.

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