SLS – Selective Laser Sintering

The first in a series of posts looking at rapid prototyping technologies will outline one of the most common processes, Selective Laser Sintering. As seen previously on Ponoko with Noel Wilson’s nylon sintered shopping cart.
sls 3
Selective Laser Sintering (SLS) is a rapid prototyping and short run rapid manufacturing process. It was developed by Carl Deckard (A process similar to SLS was invented by R.F. Housholder who patented the concept in 1979 but did not commercialize it. SLS was patented by Deckard in the mid-1980s) for his masters thesis at the University of Texas and is now used by to create a variety of prototypes. This is cutting edge technology, which can be applied to almost every industry, including electronics, aviation, aerospace, automotive, oil refining, pump and valve applications, medical tools, implants and surgical planning, as well as military equipment and others.
The process basically begins with a computerized 3D solid model of a part, which the computer slices into extremely thin layers (0.003 to 0.010 inch). This cross sectional data is then sent to the selective laser sintering machine to selectively guide the laser beam over a correspondingly thin layer of powdered material including polymers (nylon, also glass-filled or with other fillers, and polystyrene), metals (steel, titanium, alloy mixtures and composites) traditional waxes, and foundry sand. These powders fuse or “sinter” under the heat of the laser. Layer by layer and feature by feature the digital solid model is recreated into a real functional part, ready for use, part in hand, in just hours or days, rather than months.
laser sintering

The chamber where the sintering happens is heated to just below the material’s melting point so the heat of the laser does not need to be extremely high for it to work. This has led an unrealized theory, that a SLS device could be constructed using solar power (see Heliakon Solar Sintering Lab). But why wait when you could build your own sugar fabricator like Evil Mad Scientist’s CandyFab 4000


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