Selective Laser Sintering Explained

If you've got any interest in 3D printing, chances are you've come across a lot of acronyms you're not sure of. SLS among them, especially since it's one of the most commonly talked about techniques.

So, what does SLS mean?

Selective laser sintering is an advanced method used in 3D printing, combining the power of lasers with the precision of computer-aided designs.

Ready to get down to the brass tacks of the matter? Read on and we'll break down the SLS process for you.

What is Sintering?

To understand how a selective laser sintering machine works, we need to have a good handle on sintering.

Sintering is a process by which materials are fused together with either heat or pressure to form larger structures. A good example in the wild would be a glacier, which is formed as masses of snow create large amounts of pressure that eventually results in a solid final body.

The process occurs on a molecular level, creating solid structures out of material which was previously separated without the need to melt the material entirely.

What Does SLS Mean?

SLS uses a laser to provide heat, causing powdered materials to fuse together without actually melting them.

In practice, an SLS machine repeatedly spreads a thin layer of powder which is then fused together by a laser. It's a relatively simple process to the untrained eye, but in practice, things get rather complicated.

The laser's power at its peak, instead of the duration, determines the density of the working material. That means high-powered pulse lasers are generally used, the sintering effect comes from the impact of the high energy laser.

Tight temperature controls and a laser with a high power output are a stringent requirement to make SLS work. Without them, the viability of the end product can is lower. Reduced structural strength and a lower density being the biggest concerns.

What Advantages Does the SLS Process Offer?

SLS is still a relatively new form of manufacturing, but it's already proven it's worth in the field repeatedly. Anyone involved in any part of the product design process should spend some time to learn more about it.

The biggest advantage is simple: SLS allows for tight nesting of individual parts within the powdered material. Parts can also be stacked vertically in a deep enough layer of powder, adding another dimension to the nesting process.

The powdered material is entirely self-supporting, allowing for complex parts to print without the need for including support structures.

SLS can also work with a wide variety of materials, although it's most commonly used with plastics. Metallic parts rarely use SLS these days, a similar process in which the metal is entirely melted with a laser called selective laser melting, or SLM is used instead.

What Are SLS Printers Used For?

In the current state of the technology, SLS printers aren't exactly a common fixture in homes. They require a lot of power, a large workspace, and control of too many variables to be something you just pick up on Amazon.

The process is most often used for prototyping parts. The high end-quality of an SLS printer can lead to the parts being used in place of other, traditionally molded plastic as well.

For the most part, metal parts have taken a backseat when it comes to SLS production. While the machines can be used with metals, the advantages of actually melting the metal rather than fusing it with a laser outweigh the benefits in most cases and the SLM process can produce even more complicated parts.

SLS machines have also begun to find their place with limited-run parts for use in many industries, ranging from aerospace to the medical field.

Are There Any Disadvantages?

The parts which come from the selective laser sintering process are quite strong, and the ability to use different materials and quickly create parts with angles not available with other methods is a pretty big plus.

There are only two big disadvantages when we're talking about SLS:

  • The machines are expensive, bulky, and generally not suitable for personal use.
  • The surface of the parts is porous, requiring some form of post-finishing to seal them properly.
Additionally, they're not really suitable for parts which require enclosed cavities. The sintering process seals the exterior but removing the remaining powder from inside the cavity is problematic... especially if it's to remain sealed.

What's The Future of SLS Look Like?

SLS manufacturing is still in its infancy. While there are a lot of industrial uses for the technique it's been slower to take in the private market.

Fortunately for 3D printing hobbyists, however, there are machines which are being developed for home use. They're not readily available but if you have money and patience you can find a desktop-sized SLS printer.

The new wave of machines for industrial use are proving to be much faster than previous models, increasing the ability to use them for larger production runs.

In short: selective laser sintering is obviously here to stay but it's hard to know just yet if it will move beyond rapid prototyping and into a large scale manufacturing process.

Fused and Ready

What does SLS mean? Well, it's simple.

Just another one of the world-changing additive processes which are sure to shape our world for the near future. Stay tuned to see just how much potential this technology has.

But while you're doing that, why not check out our technology section for the latest tech news and tips?