The SLS 3D printer market is looking to be shaken up with yet another (relatively) low price SLS 3D printer currently in the research and development stage in Italy. The SnowWhite is a cold SLS 3D printer by Sharebot that they are getting ready to unveil at the London 3D Printshow.
Looking at the images they are still early on in the process, using a round piston as a print bed (round pistons are easier, ask Andreas Bastian with his Open SLS project) and a fairly small build area. With the industrial 3D printers Shapeways uses for SLS 3D printing made by EOS, we heat the Nylon powder to just below melting point, then the laser raises the temperature only slightly to sinter the material from powder to solid. Sintering the Nylon without pre-heating may cause greater thermal shock to the parts, and increase the power required of the laser, but it may also make it faster to cool down which could be a huge advantage to getting prototypes out faster.
To get some insight from someone who has actually experimented with ‘cold SLS’ I asked Andreas Bastian to see if he could see an advantage over ‘pre-heated’ SLS.
I would be hard-pressed to list the performance advantages of cold SLS– while it saves on energy and BOM cost, the thermal gradient the material is subjected to is significantly larger (possibly leading to material degradation) and the curling/warping due to the massive thermal contractions of the material require support (really restraint) structures. It’s the heated chamber in SLS that allows such freedom of form and geometry– an unheated SLS machine will have nearly all the same geometry constraints as an FDM machine, including the necessity of adhering the print to a build surface. That being said, support/restraint structures for SLS are new territory and there may be viable options there. As many of the low-cost FDM machines have demonstrated, it may not be necessary to fully replicate the process used at the industry level (heated chambers). That being said, I would like to see some ASTM D638 tensile testing data before I print any functional parts on their system.
Sharebot are pitching the SnowWhite SLS 3D printer to sell for under $26,000 USD when it hits the market to join the Ice 1 & Ice 9 by Norge Systems in the first wave of relatively low cost SLS 3D printers that may spread in a similar manner as FDM 3D printers have over the past 4 years.