Direct metal laser sintering
Direct metal laser sintering (DMLS) is an additive metal fabrication technology developed by EOS out of Munich, Germany. The process involves use of a 3D CAD model whereby a .stl file is created and sent to the machine’s software. A technician works with this 3D model to properly orient the geometry for part building and adds supports structure as appropriate. Once this ‘build file’ has been completed, it is ‘sliced’ into the layer thickness the machine will build in and downloaded to the DMLS machine allowing the build to begin. The DMLS machine uses a high-powered 200 Watt Yb-fiber optic laser. Inside the build chamber area, there is a material dispensing platform and a build platform along with a recoater blade used to move new powder over the build platform. The technology fuses metal powder into a solid part by melting it locally using the focused laser beam. Parts are built up additively layer by layer, typically using 20 micron layers. This process allows for highly complex geometries to be created directly from the 3D CAD data, fully automatically, in hours and without any tooling. DMLS is a net-shape process, producing parts with high accuracy and detail resolution, good surface quality and excellent mechanical properties.
DMLS has many benefits over traditional manufacturing techniques. Speed is the most obvious because no special tooling is required and parts can be built in a matter of hours. Additionally, DMLS allows for more rigorous testing of prototypes. Since DMLS can use most alloys, prototypes can now be functional hardware made out of the same material as production components.
The advantages do not stop with prototyping; DMLS is one of the few additive manufacturing technologies being used in production. It allows more design freedom, and more efficient designs in technical applications. Since the components are built layer by layer, it is possible to design internal features and passages that could not be cast or otherwise machined. Complex geometries and assemblies with multiple components can be simplified to fewer parts with a more cost effective assembly. DMLS does not require special tooling like castings, so production runs can be shorter and supply chains can carry less inventory.
This technology is used to manufacture direct parts for a variety of industries including Aerospace, Dental, Medical and other industries that have small to medium size, highly complex parts and the tooling industry to make direct tooling inserts. With a build envelop of 250mm x 250mm x 185mm height, and the ability to ‘grow’ multiple parts at one time, DMLS is a very cost and time effective technology. The technology is used both for rapid prototyping, as it decreases development time for new products, and production manufacturing as a cost saving method to simplify assemblies and complex geometries.
Currently available alloys used in the process include 17-4 and 15-5 Stainless Steel, Maraging Steel, Cobalt Chromium, Inconel 625 and 718, and Titanium Ti6Alv4. Almost any alloy metal can be used in this process once fully developed and validated.