How Selective Laser Sintering Works
An additive manufacturing layer technology, SLS involves the use of a high power laser (for example, a carbon dioxide laser) to fuse small particles of plastic, metal, ceramic, or glass powders into a mass that has a desired three-dimensional shape. The laser selectively fuses powdered material by scanning cross-sections generated from a 3-D digital description of the part (for example from a CAD file or scan data) on the surface of a powder bed. After each cross-section is scanned, the powder bed is lowered by one layer thickness, a new layer of material is applied on top, and the process is repeated until the part is completed.
In contrast with some other additive manufacturing processes, such as stereolithography (SLA) and fused deposition modeling (FDM), which most often require special support structures to fabricate overhanging designs, SLS does not need a separate feeder for support material because the part being constructed is surrounded by unsintered powder at all times, this allows for the construction of previously impossible geometries. Also, since the machine’s chamber is always filled with powder material the fabrication of multiple parts has a far lower impact on the overall difficulty and price of the design because through a technique known as ‘Nesting’ multiple parts can be positioned to fit within the boundaries of the machine. One design aspect which should be observed however is that with SLS it is ‘impossible’ to fabricate a hollow but fully enclosed element. This is because the unsintered powder within the element can’t be drained.