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Resources3D Printing DesignSLS vs. SLM: Here’s What You Should Know About These Printing Methods

SLS vs. SLM: Here’s What You Should Know About These Printing Methods

picture of Kat de Naoum
Written by
Rebecca Piccoli headshot
Updated by
 3 min read
Published July 15, 2022
Updated January 3, 2025

We’ve put together a detailed comparison of two popular 3D printing types

Plastic 3D printing. Image Credit: Shutterstock.com/Alex_Traksel

You’ll have no trouble finding a 3D printing method that works for the products you’re trying to build. The difficulty comes down to deciding between different additive manufacturing options. When you’re shopping around for options, two types that often go head to head in comparison are selective laser sintering (SLS) and selective laser melting (SLM), and understanding what both can offer makes it easier to determine what’s best for the products you’d like to develop.

"SLS is a plastics process, producing parts in nylon. It is suitable for prototyping and limited production. SLM is a metal process producing parts in limited steel and aluminum alloys. It is suitable for prototyping primarily. Both use lasers to melt powder, but for very different materials and outcomes."
Christian Tsu-Raun,
Team Lead, Manual Quoting

What Is Selective Laser Sintering (SLS)?

Its name gives a pretty good idea of what SLS does. It uses a laser to sinter powder together into a layer and repeats this process until the full design is finished. This type of 3D printing came out of the University of Texas in the 1980s, but the patent has since expired, meaning that it’s a technology option many companies have redeveloped and lessened the price of. 

To create parts with SLS, a CO2 laser is programmed to sinter and fuse together a polymer-based powder until it forms a layer. It’ll then create another layer until your build is complete. Then, it’ll need a period to properly cool off (usually 12 hours at the very least) and time for blasting and finishing. You can see an example of a product we made through SLS in the photo below.

SLS Xometry part
An SLS part manufactured by Xometry

What Is Selective Laser Melting (SLM)?

This kind of 3D printing method came to be in the early 21st century from Fraunhofer Institute in Germany. SLM also uses a high-powered laser on powders, but it melts it rather than sinters and works with metal powders instead of plastic ones. It builds up layers through additive manufacturing, too, and does so in a more controlled environment filled with inert gases like argon and nitrogen. Below, you can see a photo of an SLM printer.

slm 3d printer
A typical SLM 3D printer. Image Credit: Shutterstock.com/ID1974

How They Compare

The main differences between SLS and SLM are the type of powder they use and the method of combining materials they rely on (sintering vs melting). However, there are a few other properties you can look at to see differences, which you’ll find in our table below:

PropertySLSSLM
Property
Uses thermoplastic powders
SLS
Yes, such as Nylon 11 and Nylon 12
SLM
No
Property
Uses metal powders
SLS
No
SLM
Yes, including pure metals and alloys
Property
Inert gas needed
SLS
No
SLM
Yes
Property
Extensive range of materials
SLS
No
SLM
Yes
Property
Used for small to medium prototypes and production runs
SLS
Yes
SLM
Yes
Property
Extensive post-processing required
SLS
Yes
SLM
No
Property
Need for supports while printing
SLS
No
SLM
Yes
Property
Complex geometries possible
SLS
Yes
SLM
Yes
Property
Costly
SLS
Yes
SLM
Yes
Property
Print volume
SLS
Up to 550 x 550 x 750 mm
SLM
Up to 350 x 350 x 350 mm
Property
Advantages
SLS
Excellent mechanical properties, no supports are necessary even for complex designs, and powders can be recycled and reused
SLM
Rarely requires post-processing for a clean finish, has quicker lead times, and cheaper tooling costs
Property
Disadvantages
SLS
Can leave a grainy finish or texture, long lead times, warping, holes, and over-sintering is possible, especially on large, flat surfaces
SLM
Systems are expensive to run, post-processing is necessary, and you need more material to provide support for overhangs

SLS vs. SLM Comparisons

FAQs About SLS and SLM

Here are a few other questions you might be trying to answer when you’re comparing SLS and SLM. 

How are SLS and SLM similar?

These two printing types are similar in that they both use high-powered lasers to create layers and, thus fully made parts. They’re both great methods for prototyping and can both quickly and efficiently print products—even with complex designs.

What are the costs of SLS vs SLM?

Both 3D printing methods can be pretty expensive due to the technology and type of machinery needed. That said, SLS printers tend to be slightly less, ranging between $18,000 and $100,000, whereas SLM machines range between $55,000 to $350,000.

How Xometry Can Help

We have a long list of 3D printing technologies you can use here at Xometry, including SLS. Other options you can snag a free quote for are fused deposition modeling, stereolithography, and PolyJet.

Disclaimer

The content appearing on this webpage is for informational purposes only. Xometry makes no representation or warranty of any kind, be it expressed or implied, as to the accuracy, completeness, or validity of the information. Any performance parameters, geometric tolerances, specific design features, quality and types of materials, or processes should not be inferred to represent what will be delivered by third-party suppliers or manufacturers through Xometry’s network. Buyers seeking quotes for parts are responsible for defining the specific requirements for those parts. Please refer to our terms and conditions for more information.

picture of Kat de Naoum
Kat de Naoum
Kat de Naoum is a writer, author, editor, and content specialist from the UK with 20+ years of writing experience. Kat has experience writing for a variety of manufacturing and technical organizations and loves the world of engineering. Alongside writing, Kat was a paralegal for almost 10 years, seven of which were in ship finance. She has written for many publications, both print and online. Kat has a BA in English literature and philosophy, and an MA in creative writing from Kingston University.

Read more articles by Kat de Naoum

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