Stereolithography and Laser Sintering

In 1987 Chuck Hull of 3D Systems http://www.3dsystems.com launched the first stereolithography machine and shortly afterwards a reporter coined the expression ‘rapid prototyping’.  SLA is a process whereby a laser converts a liquid photopolymer into a solid plastic layer by layer. Each layer is different and a 3D model is built up on a perforated plate in the bath of photopolymer.

There is now a huge range of SLA materials with very good mechanical properties.  Surging prototype uses DSM Somos 14120 which closely simulates ABS thermoplastic.  Surging prototype mostly uses SLA models as Master Patterns to make silicone rubber moulds for vacuum casting of Polyurethane.

http://www.dsm.com/en_US/downloads/dsms/14120eng_10.09.pdf

http://en.wikipedia.org/wiki/Stereolithography

Selective Laser Sintering was commercially developed in the mid 1980′s in Texas, although a similar process dates to 1979.  It too is a laminated manufacturing process, but uses a much higher power laser to sinter plastic powder together to form a 3D prototype.  The most typical material used is Polyamide/Nylon.  It is also possible to have glass filled Nylon.  Historically it was considered that SLS parts were more durable than SLA, but as SLA materials improve, this gap is narrowing.  SLS is also considered quite wasteful as up to 30% of all non-converted powder removed so as to refresh the powder stock.  SLA has almost no material waste.

http://en.wikipedia.org/wiki/Selective_laser_sintering