The biggest advantage of selective laser sintering technology is that it can produce strong, functional parts with complex geometry. Worth to notice is that Selective Laser Sintering is a part of the BED POWDER FUSION category, that utilizes a heat source typically a laser to sinter or fuse thermoplastic polymer powder together to produce a solid part.
How does Selective Laser Sintering produce parts?
SLS process starts with spreading a thin layer of powder over the build platform. But there are some differences between SLS 3D printers. Some of them use to spread powder a recoating blade, other – like SondaSYS SL02 – recouter. Some devices have a top powder charge, in our SLS we use the side one. When the first layer of powder is prepared, the laser (usually CO2 one) scans the first layer of the part selectively sintering together the particles of powder.
When the laser has completed the sintering of a layer, the build platform moves down one layer height and the recoater spreads a next layer of powder over the newly sintered layer. The fusing and sintering process is repeated over and over again. Building the part up layer by layer, at a time.
After that, the printouts are removed from the printer (usually the build platform is taken out from the device and put on a special trolley) and both the parts and powder are allowed to cool.
In the SLS process, all manufactured parts are surrounded by unsintered powder. That means each time an SLS 3D printer uses to produce parts the entire build volume, whether the bin is full of sintered parts or not. Because of this, it is most cost-effective to fill the bin to the maximum capacity by nesting inside as many parts as possible. A great option here is an SLS 3D printer with a changeable build volume (read more here), that allows for use smaller build space to manufacture small elements or a small quantity of them.
Across most SLS machines layer high/ layer thickness is typically not adjustable, with a hundred microns been standard across most machines This limitation is not a problem in SondaSYS SLS, in which users can choose between the layer high 0.1, 0.12, 0.15 or 0.18 mm. That gives an option to speed up the whole process and finish work significantly faster.
So how do you know that SLS is the right 3D printing technology for your parts?
The most common material used in SLS 3D printing is NYLON. This material has excellent long-term stability and chemical resistance and it is also very strong and much more isotropic than FDM or SLA ones. That is why SLS parts are the best solution for functional parts and design.
One of the key advantages of selective laser sintering technology is that during the printing process manufactured parts are surrounded by powder, and thanks to that they don’t need any support material. Also, no support material is needed to be removed after printing (unlike SLA or FDM or even SLM). It also makes SLS parts generally having a very consistent and homogenous surface finish. The small laser beam spot size and very small grains of powder make the SLS technology great for parts with complex, sophisticated, tricky, and/ or tricky details. Also because the manufacturing process does not depend on support material – complex shapes and geometries can be printed. That gives SLS technology a great advantage in preparing ex. parts with hollow channels. Made in SLS technology parts have surface finish similar to high grit sandpaper. Surface with this kind of the porosity allows to dye parts easily, and in a large range of colors.
In the SLS process, various parts can be produced in a single work, offering viable economies of scale at certain build sizes. Usually, a good rule of thumb is that if parts are smaller than a fist they could be ideal for SLS batch manufacturing, but in SLS there can be successfully produced single, big elements.
The SLS parts are comparatively strong and functional as the ones from injection molding. That is why it can be a usable option for smaller parts that require production runs from 500 to 1000.
SLS is becoming more and more popular in the large range of industries which requires parts with complex geometries and strong functional, like the automotive industry or the aerospace industry. In both parts like brackets and enclosures made by SLS technology is now used every day.