Processes - Additive Manufacturing
Direct Metal Laser Sintering (DMLS)
Direct Metal Laser Sintering (DMLS) was developed jointly by Rapid Product Innovations (RPI) and EOS GmbH, starting in 1994, as the first commercial rapid prototyping method to produce metal parts in a single process. With DMLS, metal powder (20 or 30 micron diameter), free of binder or fluxing agent, is completely melted by the scanning of a high power laser beam to build the part with properties of the original material. Eliminating the polymer binder avoids the burn-off and infiltration steps, and produces a 95% dense steel part compared to roughly 70% density with Selective Laser Sintering (SLS). An additional benefit of the DMLS process compared to SLS is higher detail resolution due to the use of thinner layers, enabled by a smaller powder diameter. This capability allows for more intricate part shapes. Material options that are currently offered include alloy steel, stainless steel, tool steel, aluminum, bronze, cobalt-chrome, and titanium. In addition to functional prototypes, DMLS is often used to produce rapid tooling, medical implants, and aerospace parts for high heat applications.
The DMLS process can be performed by two different methods, powder deposition and powder bed, which differ in the way each layer of powder is applied. In the powder deposition method, the metal powder is contained in a hopper that melts the powder and deposits a thin layer onto the build platform. In the powder bed method (shown below), the powder dispenser piston raises the powder supply and then a recoater arm distributes a layer of powder onto the powder bed. A laser then sinters the layer of powder metal. In both methods, after a layer is built the build piston lowers the build platform and the next layer of powder is applied. The powder deposition method offers the advantage of using more than one material, each in its own hopper. The powder bed method is limited to only one material but offers faster build speeds.
Advantages
Material Reusability
Similar to Selective Laser Sintering (SLS), DMLS allows for the reuse of unsintered metal powder remaining after the printing process. This significantly reduces material waste and lowers overall production costs, making it a cost-effective option for manufacturing metal parts and prototypes.
Broad Material Compatibility
DMLS supports a wide range of metals, including aluminum, titanium, stainless steel, tool steel, cobalt-chrome, nickel alloys, and precious metals. This flexibility enables engineers to choose between pure metals or specific alloys to meet exact performance requirements. The technology's growing adoption continues to drive the development of new, specialized metal powders optimized for DMLS.
Direct Metal Fabrication
DMLS facilitates the direct production of metal components from digital designs, preserving the inherent material properties of the selected metal or alloy. It also allows for innovation through powder blending, enabling the creation of complex geometries and high-performance, multi-material parts.
High-Strength, Functional Components
Ideal for both prototyping and end-use applications, DMLS produces strong, durable parts using high-performance metal alloys. Because the process sinters rather than fully melts the powder, the resulting components retain superior mechanical properties and structural integrity, ensuring consistent functionality in demanding environments.
Disadvantages
High Production Costs
DMLS remains one of the more expensive additive manufacturing methods due to the cost of metal powders, high-end equipment, and operational requirements. As a result, it is best suited for industrial applications, with cost considerations potentially limiting adoption for small-scale or low-volume projects.
Extensive Post-Processing Needs
To achieve the desired mechanical properties and surface quality, DMLS parts often require significant post-processing. This can include heat treatment, machining, support removal, and de-powdering. These additional steps increase both lead times and production costs, necessitating careful planning and resource allocation.
Capabilities
Disclaimer: All process specifications reflect the approximate range of a process's capabilities and should be viewed only as a guide. Actual capabilities are dependent upon the manufacturer, equipment, material, and part requirements.