DMLS vs. SLM: Key Differences in 3D Metal Printing

Direct metal laser sintering (DMLS) and selective laser melting (SLM) 3D printing methods both fall under the category of powder bed fusion (PBF). They also both use laser beams—sometimes more than one at a time, and are compatible with different metal powders. Given these similarities, it’s easy to confuse the two… but considering one of the printers can cost a million bucks—double the price of the other—it’s safe to say that they are different in many ways. Read on to find out how.

DMLS Definition and Comparison to SLM

DMLS, a trademark owned by additive manufacturing company EOS GmbH, is used to make metal parts. It’s still often referred to as a sintering method, simply because when it was first invented in the mid-90s, it only sintered metal. EOS says that “DMLS” is actually a German acronym for Direkt Metall Laser Schmelzen, which more accurately translates to the melting of metal, instead of sintering. The company made the technology commercially available in 1995, and modern machines fully melt the metal powder in the printing process, something that creates much stronger parts.

It usually uses a high-powered fiber laser beam that traces each layer’s cross-section and melts the particles of metal together. When each layer is printed, the bed moves down so power can be applied to a new layer on top, and then it starts again. During the process, the build chamber is filled with inert gas to stop any oxidation. The following image breaks down what a DMLS printer typically looks like:

DMLS vs. SLM: Technology Comparison

DMLS and SLM are both powder bed fusion technologies that melt the metal powder using lasers. SLM units typically contain higher-powered lasers than do DMLS (1000 watts vs 400 watts). The output power of those SLM lasers can also be varied to alter the part’s detail resolution.

DMLS vs. SLM: Material Comparison

DMLS and SLM can print in a wide range of metals and metal alloys. Typical examples include: titanium Ti64, stainless steel 316, and nickel alloys like NI718.

DMLS vs. SLM: Product Applications Comparison

DMLS is marketed extensively in the medical industry for items such as implants and dental bridges. SLM, on the other hand, serves a broader range of industries such as automotive and aerospace.

DMLS vs. SLM: Print Volume Comparison

SLM machines typically have larger build volumes when compared to DMLS. Their multiple lasers also help them exploit the space more efficiently.

DMLS vs. SLM: Surface Finish Comparison

Both technologies create similar surface finishes because they operate on the same powder bed fusion principle.

DMLS vs. SLM: Cost Comparison

The manufacturers of both SLM and DMLS offer a wide range of machines. However, the entry-level version of either type typically costs more than $350,000. Because it employs more lasers and can print thicker layers, SLM systems can finish lower-resolution jobs much quicker than DMLS. Faster print time results in lower cost per part.

What are the Similarities Between DMLS and SLM?

Listed below are some of the similarities between DMLS vs. SLM.

DMLS and SLM both use a laser beam to melt powdered metal.
DMLS and SLM can use many different metal powders to produce parts.
Both technologies can employ multiple lasers at once to increase the production rate.

What are the Other Comparisons for DMLS Besides SLM?

An alternative technology to DMLS is:

DMLS vs. Binder Metal Jetting: Binder Metal Jetting binds metal powder together using a polymer binder. The binder is applied in the shape of the part cross-section. Then, as with DMLS, another layer of powder is added on top and the process repeats. When the part is complete, it must be post-processed to sinter/fuse the metal powder together and burn off the binder.

What are the Other Comparisons for SLM Besides DMLS?

Aside from DMLS, another alternative technology to SLM is:

SLM vs. DED: DED (Directed-energy deposition) is a metal printing technology that feeds a metal wire through a printing nozzle. The metal is melted at the nozzle and deposited on the build plate layer by layer, similar to FDM printing. This produces parts that have homogenous mechanical properties.

Frequently Asked Questions on DMLS vs. SLM

What examples of materials can I use with these 3D printers?

Both of them work with metal powders, but they have slightly different preferences of what they like to work with. SLM printers are better for pure, high-strength metals (titanium, aluminum, stainless steel, cobalt-chromium), while DMLS printers are designed more for metal alloys (nickel-based superalloys, tool steels, and aluminum alloys).

What’s the difference between DMLS and binder metal jetting?

Binder metal jetting bonds metal together with a polymer binder instead of a laser-like DMLS does. This binder is applied in the shape of the part’s cross-section. When each layer is finished, another layer of powder is added and the process repeats. The finished part will need to be post-processed to fuse the metal powder together, and burn the binder off.

What’s the difference between SLM and DED?

Instead of metal powder, DED (directed-energy deposition) feeds a metal wire through the printer’s nozzle to make parts. The wire is melted at the nozzle and dropped into the build plate, similar to how fused-deposition modeling printers do but with filament. DED can make parts that are consistent and uniform throughout their entire construction, while SLMs are better at complex and precise parts.

What are the Mutual Alternatives to the DMLS and SLM?

The main alternative is probably EBM (electron beam melting). It’s similar to both DMLS and SLM in that it uses an energy beam to melt powder, but instead of a laser, it uses an electron particle beam.

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.