Selective Laser Sintering (SLS) 3D printers

The SLS process

What steps does it take to make an object with an SLS machine? The process falls into seven main steps.

Create the print data with CAD software.
Load the plastic powder and start printing.
Spread the plastic powder and sinter the areas to be printed with a laser (melt them and let them solidify).
When the first layer is sintered, spread more powder on top and sinter it again.
When printing is finished, let the very hot build cool down.
After cooling, take the objects out of the powder.
Blast the surface to remove the powder stuck to it, and the part is done.

The video below explains the SLS process clearly. It is made by 3D Systems, a company that sells SLS 3D printers.

Here are the advantages and disadvantages of Selective Laser Sintering (SLS).

Advantage 1: Strong parts
SLS can make strong objects. The powder is melted by a laser or similar heat source, and material melted by heat solidifies densely, so the finished parts are strong.
Advantage 2: No supports needed
Resin printing and FDM need support structures, but in SLS the surrounding powder holds the shape and acts as the support, so no separate supports are needed.

Disadvantage 1: Rough surfaces
Parts come out with a rough surface. If a smooth finish is needed, they have to be polished.
Disadvantage 2: Long wait before removal
With resin printing and FDM, parts can be removed right after printing. With SLS, parts are very hot and must cool down before removal so that they do not warp. Cooling usually takes from several hours to about 48 hours.

The Selective Laser Sintering printers listed on 3Techs, with build size, price and other specs side by side.

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