Selective Laser Sintering (SLS) Process

Selective Laser Sintering (SLS) is an additive Rapid Prototyping (RP) technique that uses a high power laser (like CO2 beam) to fuse small particles of plastic or metal powder into desired 3D shape. The laser selectively fuses powdered material by scanning cross-sections generated from a 3D digital description of the part (from CAD data) on the surface of a powder bed.

After the first cross-section is sintered, the powder bed is lowered by one layer thickness so that the laser beam will sinter the next layer of part. The process repeats until the complete geometry is sintered from powder.

SLS RP technique can be used for wide range of materials like polymers (nylon, glass filled or with other fillers, polystyrene), metals like steel, titanium, alloy mixtures and composites. Green sand also can be used in this process. However, these powders will be specially prepared by manufacturers to suit a particular SLS machine.

This is most powerful RP technique to form complex geometric shapes and even the assemblies. Almost any geometry which can be modeled in CAD can be produced physically.

SLS does not require support structures unlike other RP processes such as Stereolithography (SLA) and Fused Deposition Modeling (FDM) due to the fact that part being built is always surrounded by unsintered powder all the time. The part can be directly taken out from powder after the sintering process is completed. The remained powder can be reused in machine with appropriate combination with unused powder.

In Hyderabad, Andhra Pradesh, India, the Department of Mechanical Engineering of Osmania University has procured a SLS machine recently from EOS Gmbh.