Direct Metal Laser Sintering (DMLS) is an industrial 3D printing process that enables the production of detailed, intricate metal parts and complex assemblies in a single build. It belongs to the Powder Bed Fusion (PBF) family and is often described as the metal counterpart of Selective Laser Sintering (SLS), which primarily uses polymer powder.
DMLS printing has been widely adopted in industries such as aerospace and automotive due to its ability to reduce material waste and shorten both prototyping and production times. Since it does not require expensive tooling, DMLS is often a more cost-effective solution for one-off and small batch parts—and in some cases, even for production runs of several thousand units—compared with traditional manufacturing methods.
1. CAD Model Preparation: Export your design or 3D model from any CAD software in a 3D-printable file format (.STL is recommended, and most widely supported). The CAD model is then digitally sliced into thin cross-sectional layers using a specialized slicing software and uploaded to a DMLS machine, serving as the starting point for the printing process.
2. Powder Deposition and Prep: The build chamber is purged with inert gas, such as argon, to minimize oxidation and is heated to the target build temperature. A thin layer of metal powder (typically 20–60 microns) is then evenly spread across the build platform, and a precise high-power laser selectively sinters the powder particles together.
3. Layer-By-Layer Laser Sintering: After each layer is completed, the build platform lowers, and a new layer of powder is spread across the platform. This process repeats until the final object or shape is fully formed.
4. Cooling, De-powdering and Support Removal: Once the print(s) are complete, the build chamber is allowed to cool to room temperature. The finished 3D-printed metal parts are then carefully removed from the build platform and de-powdered.
Once a part is printed, it’s not uncommon to turn to secondary machining operations.
5. Support Removal by Machining: Unlike its plastic counterpart SLS, DMLS requires support structures to prevent specific features from sinking through the powder. These supports are often made using the same metal as the build and will need extensive post-processing (often via machining or wire cutting) to be removed, which can be time-consuming and costly.
6. Machined Tighter Tolerances: DMLS printers can produce accurate parts, with typical tolerances to ±0.1 – 0.2 mm. When critical features require even tighter tolerances, sometimes they can be post-machined to ±0.05 mm.
A key strength of Metal Additive Manufacturing (Metal AM) is the ability to process high-strength metals, such as Inconel and Cobalt Chrome, that are otherwise difficult to machine. Between DMLS and SLM, manufacturers have a wide selection of metal and metal alloy powder materials to choose from. Below is a list of materials commonly used in metal 3D printing.
| Materials | Characteristics |
| Aluminium Alloy |
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| Titanium Alloy |
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| Stainless Steel |
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| Nickel Superalloys (Inconel) |
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| Cobalt-Chrome Superalloys |
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When the build finishes, parts are fully surrounded by loose powder. Unlike polymer powder bed fusion (such as SLS or MJF), the parts are attached to the build plate with support structures made from the same metal. Support is required to control warping and distortion caused by high processing temperatures.
Finished DMLS printed parts have a grainy structure that often requires extensive post-processing to achieve a smooth, aesthetic finish. The surface quality can be improved through various surface finishing techniques, such as sanding and spray painting. Surface finishing options, such as electroplating and polishing, can also be applied to DMLS components to enhance functionality.
| AlSl10Mg | ✔ Anodizing ✔ Chrome Plating ✔ Electroless Nickel Plating ✔ Painting ✔ Passivation✗ Brushing ✗ Powder Coating |
| SS316L | ✔ Chrome Plating ✔ Electroless Nickel Plating ✔ Painting ✔ Passivation✗ Anodizing ✗ Brushing ✗ Powder Coating |
Certain features, such as wall thickness, in DMLS designs can be tricky and differ depending on material selection, orientation, and resolution. Staying within a set of geometric recommendations can help ensure better part quality and a successful print. Learn how to design mating parts, pins, overhangs and more, in our DMLS 3D Printing Design Guide.
DMLS can be used interchangeably with selective laser melting (SLM). The main difference between them is that the laser in SLM heats up the powdered metals until they melt into liquids and join together. In the DMLS process, the laser only heats the materials up just enough to allow the surfaces to meld into one another.
Direct metal laser sintering allows us to combine different types of metal powders, or even incorporate plastic materials, because we don’t have to wait for each individual component to reach its melting point.
The DMLS process produces a porous metal part, while SLM printers yield a much more uniform build. As we mentioned in the previous section, porous metals are great for manufacturing prosthetics. But there is a slight disadvantage, as well, which we’ll discuss later in the article.
Several different industries use DMLS to produce high performance functional end-use parts.
The medical and dental industries, for example, use DMLS 3D printing to build custom prosthetics that support existing bones or replace bones that are lost using biocompatible metals. In this application, the porous nature of DMLS parts is perfect because it allows the bone to grow into it, thus strengthening the entire structure.
DMLS works with lightweight metals like titanium and aluminium. It also allows for greater design freedom, which provides automotive and aerospace sectors the opportunity to produce lightweight complex parts while maintaining the same structural strength.
