SLS and its beam-melting derivatives have been strictly the domain of giants, often employed by large service bureaus offering print jobs costing more than some personal 3D printers. Implementations by 3D Systems, EOS, Arcam AB and ExOne range from a couple hundred thousand dollars to millions.
For the extremely steep price, users not only get quality, they get certain features that only SLS can provide. The array of raw material options is breathtaking – precious metals, titanium, stainless steel, plastics and various sands capable of producing glassy and ceramic-like output, to name only a few. And because the current layer of an SLS part is always sitting on a bed of powder, no print job ever requires a support structure. For this reason, objects such as Kevin Mack's abstract art can only be produced with SLS.
Ever since certain SLS patents expired in 2014, consumers have been waiting to see an SLS 3D printer costing less than $6,000. Unfortunately, it isn't that easy. Conceptually, SLS isn't necessarily more complex than SLA. However, it is much more difficult to do correctly than SLA and in fact it is more dangerous.
The build chamber of an SLS system is typically kept only a few degrees cooler than the temperature required for the laser to sinter the powder material. Plastics require temperatures over 180°C. That's as hot as a baking oven, but it's nothing compared to tungsten carbide with a melting temperature greater than 2,700°C. Metal sintering also requires an inert gas atmosphere. Imagine what it takes just to design an enclosure to deal with these issues and a million dollar price tag starts to seem reasonable. Engineering against risk when properly incorporating this technology is no small task and that's why we haven't seen a flood of SLS printers since the patents expired.
Now three bold engineers with tech sector experience are trying to make the $5,000 SLS dream a reality with Sinterit. Paul Szczurek, Konrad Glowacki and Mike Grzymała-Moszczyński include companies like Google and ABB on their resumes, so overcoming technical difficulty isn't new to them. Based on the output photos they've recently released, it looks they are tackling the stiff requirements of SLS.
The Sinterit SLS printer will have a build envelope of 130mm x 170mm x 130mm. Projected materials are PA12-based, possibly with options for fiberglass, carbon fiber and aluminum additives. PA12 is a nylon with a relatively low melting temperature of 190° - 210°C – minimal heat containment and power requirements in the SLS arena.
Sinterit will likely be introduced to the public via a crowdfunding launch before this year is over.
Note: Some of these photos are of very small objects shot at close range, making it is possible to see the signature porous surface for which sintering is known. For example, the balls in the bearing are only 12mm in diameter. This aspect of SLS is valued in orthopedic circles, because titanium SLS parts graft well with bones. The surface texture is much more difficult to see with the naked eye, but epoxy coating can be added to smooth and gloss the parts, for those who desire it.