Mold Making With Selective Laser Sintering

In this method, powdered thermoplastic or metal material is melted with a laser beam to build three-dimensional parts. Using laser technology, this system melts and sinters metal powders to produce metal parts and molds, and it can work with all kinds of metal.

Since the metal parts produced with this system are nearly 100% dense, all the processes applicable to homogeneous metals can also be applied to these parts.

Sintering is the process in which a powdered material is exposed to a temperature below its melting point for a certain period, causing the powder particles to fuse together starting at the points where they touch. Above, the 4 stages of sintering are shown.

As with all 3D printing methods, creating an object with an SLS machine starts with a computer-aided design (CAD) design. This CAD file is then converted to the .STL format, which can be understood by 3D printers.

Video about production using Selective Laser Sintering

Powder is spread in a thin layer onto a platform inside the build chamber. The printer heats the powder to a temperature slightly below the raw material’s melting point. The rest of the process runs almost the same way as familiar 3D printing methods.

Examples of Parts Produced With Selective Laser Sintering

Mold halves and a printed part made with selective laser sintering (above)

Plastic injection mold half made with selective laser sintering

Punch and metal powder prepared with the SLS method

M12 Allen bolt

Mold Bushings

bending punch made with selective laser sintering

Bending punches prepared with SLS. This die has stamped 150 parts.

Valves made with SLS

Advantages of the Selective Laser Method

High part accuracy, no need for part supports during manufacturing. Since SLS doesn’t require support material, parts with hollow sections can be printed easily and accurately. Engineers and manufacturers choose selective laser sintering for its design freedom, high productivity and throughput, low cost per part, and proven end-use materials.
It’s easy to produce objects with irregular shapes.
Parts have high strength and rigidity.
Because of their reliable mechanical properties, the parts produced can replace typical injection-molded plastics.

A core made for use in plastic injection molding. Note the cooling channels inside it.

Plastic injection mold made with SLS

High-Temperature Sintering

SLS (Selective Laser Sintering) builds layers by fusing powder material together with high heat, without fully melting it.

No Support Structure Needed

In SLS, since the unfused powder acts as a natural support, complex geometries don’t need a separate support structure.

High Cost

SLS equipment and powder materials are generally more costly than other 3D printing methods like FDM.

Disadvantages of the Selective Laser Method

If a smooth surface or watertightness is required, SLS parts may need post-processing due to their internal porosity.
Large flat surfaces and small holes aren’t printed accurately with SLS, since they’re prone to warping and excessive shrinkage.
Lead times are longer than other 3D printing technologies like FDM and SLA.

Applications of Selective Laser Sintering

SLS technology is widely used across many industries around the world thanks to its ability to easily produce complex geometries. Its most common application is prototype parts, such as investment casting patterns, automotive components, and wind tunnel models.