Rapid Prototyping - Selective Laser Sintering (SLS)

Selective Laser Sintering (SLS®, registered trademark of DTM™ of Austin, Texas, USA) is a process that was patented in 1989 by Carl Deckard, a University of Texas graduate student. Its chief advantages over Stereolithography (SLA) revolve around material properties. Many varying materials are possible, and these materials can approximate the properties of thermoplastics such as polycarbonate, nylon, or glass-filled nylon.

As the figure shows, an SLS® machine consists of two powder magazines on either side of the work area. The leveling roller moves powder over from one magazine, crossing over the work area to the other magazine. The laser then traces out the layer. The work platform moves down by the thickness of one layer and the roller then moves in the opposite direction. The process repeats until the part is complete.

SLS Highlights

  • Laser beam selectively fuses powder materials: nylon, elastomer, and some metals.
  • Advantage over SLA: Variety of materials and ability to approximate common engineering plastic materials.
  • No milling step so accuracy in z can suffer.
  • Process is simple: There are no milling or masking steps required.
  • Living hinges are possible with the thermoplastic-like materials.
  • Powdery, porous surface unless sealant is used. Sealant also strengthens part.
  • Uncured material is easily removed after a build by brushing or blowing it off.