Selective laser sintering (SLS) is a process whereby a powdered material is sintered by a high power laser; this process binds the powder together to create a 3d shape. The process begins with an STL file being sliced into layers that the SLS machine can build. Once this data is transferred to the machine, it puts down a layer of powder which the laser then scans the first layer onto. After each layer, the powder bed drops by the thickness of one layer and another layer of powder is laid on top – the process then repeats until all the parts are complete.
Unlike in other additive manufacturing processes, such as SLA and FDM, a support structure is not required with SLS, as the parts are always surrounded by un-sintered powder. This means that every part in a build is kept stable and geometries that would otherwise be thought of as impossible can be manufactured. This also means that once a build is complete, the parts are left buried inside an amount of un-sintered powder – it is then the job of the operator to remove the parts from within this powder.
Once the parts are built there can be some layer lines & faceting left on the surface of the parts, these can usually be removed by a number of different finishing methods. SLS materials can be finished and painted to a high standard; however, the finish can vary depending on the material used. There is a vast range of materials that can be used in an SLS machine, the most common being nylon – available with or without a number of filler materials designed to strengthen the finished parts.