When you think of materials for 3D printing functional prototypes and end-use parts, we’re betting that plastic comes immediately to your mind. But did you know that it is also possible to 3D print objects using metal?
Get to know the basics of direct metal laser sintering, also known as DMLS 3D printing. Find out why the process is worth considering for your next project, learn about how DMLS works, discover the materials and finishing options available, and the advantages and disadvantages of the process to bear in mind.
Direct metal laser sintering (DMLS) is a metal additive manufacturing (metal AM) technique that belongs to the Powder Bed Fusion family and is often referred to as the metal counterpart of selective laser sintering (SLS). It works by heating up powdered metal, layer by layer, at select points so that the layer fuse into a single unit.
DMLS opens up a whole new world of creative possibilities in applications in multiple industries. It allows us to build a single metal object and incorporate complex shapes into it that are nearly, if not completely impossible to make through traditional manufacturing methods. And as DMLS technologies advance, the number of possibilities will only increase.
The DMLS 3D printing process begins with a CAD model that needs to exported into a 3D printable file format (an STL format). Using your model, the DMLS process uses a high-power laser beam to selectively fuse a layer of metallic powder together. The process repeats layer-by-layer until the final object is formed.
CNC machining after DMLS
Once a part is printed, it’s not uncommon to turn to additional machining options.
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.
Find out how to design mating parts, pins, overhangs and more, in our DMLS 3D Printing Design Guide.
DMLS is often interchanged 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.
A key strength of 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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Finished DMLS 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 media blasting, sanding and spray painting. Surface finishing options, such as electroplating and polishing, can also be applied to DMLS components to enhance functionality.
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.