SLS stands for Selective Laser Sintering, which is a 3D printing method where a polymer or thermoplastic powder is sintered by pointing a laser that transforms the powder into a solid plastic piece. This process is part of the group of Powder Bed Fusion technologies, and it achieves the fusion of the material by layers that represent cross sections of the model built in the CAD/CAM software.
Although the explanation above seems to be describing a newly developed technology, the truth is that SLS 3D printing is one of the oldest additive manufacturing methods, first developed in the 80s by doctors Carl Deckard and Joe Beaman at the University of Texas at Austin.
As with other 3D printing processes, it all begins with a 3D CAD model that is processed by the software of the printer to generate the layers that will be printed. After that, the SLS 3D printing process takes the following steps:
1.The platform where the piece is printed is located inside a chamber known as the powder bin or build chamber. To prepare the build platform, a thin layer of the plastic powder is spread on it inside the chamber.
2.The platform is then preheated near to the melting temperature of the material in order to aid the laser to reach the proper temperature to solidify the plastic along the path described by the software to form the layer of the model. In some cases, the powder that is not fused serves as support for the part being built and there’s no need for printing support structures.
3.After one layer is finished, the build platform is lowered inside the chamber. It moves a distance equal to one layer, which in most printers ranges between 50 and 200 microns. When positioned as required, a new layer of plastic powder is spread on it by a part called recoater. Then, the laser does its job again generating the corresponding layer. This step is repeated until the plastic prototype or part is completed.
4.When the part is completely printed, it is left to cool down progressively until it is ready to be taken away from the chamber and cleaned by removing the powder that was not fused.
The main problem or limitation that some people have found with SLS 3D printing is that it was mainly focused on industrial systems, making the printers bulky and very expensive with long printing times.
However, recent technological developments have provided the possibility of having desktop SLS 3D printers and printers capable of fast printing multiple parts at the same time accurately, thus making this technology a good solution for small businesses that require speed and reduced waste.
Anyways, if you are still dealing with some doubts, the recommendation is to consult with an expert to avoid undesired failures and reduce costs related to repeated work in trial an error.