Increased Efficiency Through Proper Use of Metal 3D Printing

Technical Article by Niko Mroncz, Head of Sales Engineering Xometry Europe

3D printing is well known for its ability to create intricate geometries and fine details that are difficult to achieve with traditional manufacturing methods. However, particularly in metal printing, additive manufacturing offers remarkable possibilities. With this technology, highly detailed and complex components are produced with exceptional precision from a variety of metals. Direct Metal Laser Sintering (DMLS), often also referred to as Direct Metal Laser Melting, is used for this purpose. On our production platform Xometry, we handle daily orders for prototypes and functional parts using this exciting technology. Time and again, we encounter the same design errors—ones that could easily be avoided.

When metal printing is applied correctly, innovations can be realized much faster. Especially in combination with a production platform like Xometry, users can significantly increase their productivity. The platform instantly connects developers with suitable metal printing manufacturers, as well as providers for dozens of other manufacturing technologies. As a result, parts become available within a few days—accelerating processes and shortening development times.

One of the key advantages of DMLS over traditional metalworking is the high degree of design freedom and increased productivity in development and production. However, to fully leverage these benefits, critical design factors must be considered early in the development phase: appropriate support structures, optimal wall thickness, and adequate spacing between part elements.

In DMLS, it is also important to avoid bulky parts. The larger the printed volume of a single piece, the greater the risks for dimensional accuracy due to shrinkage or deformation. Below are key best practices derived from our experience that should be considered when designing for metal 3D printing:

Support Structures
Geometric features such as overhangs, arches, and surfaces with angles greater than 30 degrees require support structures in DMLS. While essential, these increase material consumption and prolong production times. It is recommended to design self-supporting elements with angles of 45 degrees or more to reduce the need for supports. Angles under 30 degrees, chamfers, and fillets help minimize the requirement for additional supports. Proper support for horizontal surfaces, large holes, and overhangs is crucial to preventing movement during printing, which could lead to inaccuracies or even machine failures.

Wall Thicknesses
The wall thickness in metal 3D printing varies depending on the material, part orientation, and desired resolution. Thicker walls improve structural integrity and are generally considered best practice. A minimum wall thickness of 0.8 mm is recommended to reduce breakage risks. For supported walls connected on two or more sides, a thickness of at least 1 mm should be used. Unsupported walls, connected only at one side or corner, should have a minimum thickness of 1.2 mm. Maintaining consistent wall thickness throughout the design enhances stability.

Overhangs
Overhangs refer to abrupt changes in a part’s geometry. Compared to self-supporting angles, overhangs have more gradual slopes. Overhangs greater than 0.5 mm generally require additional supports to prevent damage or deformation during printing. However, pushing the limits of feasibility can lead to rougher surfaces, lower resolution, or even process failure. It is advisable to include supports for overhangs exceeding 0.5 mm or angles greater than 45 degrees. Chamfers or fillets in overhanging geometries improve self-supporting properties.

Internal Channels and Holes
A major advantage of DMLS is the ability to produce complex internal channels and holes. The most effective designs follow the contours of the part’s surface, facilitating even cooling and weight reduction. Channels should be limited to a maximum diameter of 8 mm and should ideally have teardrop or diamond-shaped cross-sections to minimize deformation and enhance surface quality. Holes should have a minimum diameter of 1 mm, while teardrop-shaped holes are ideal when the opening is not aligned with the build direction. Holes between 0.5 mm and 6 mm can be printed without supports, whereas holes larger than 6 mm require a change in orientation or additional supports. Holes smaller than 1 mm should be post-processed for better precision.

Thin Pins and Small Details
Pins and columns refer to tall, slender elements with circular cross-sections. A minimum diameter of 1 mm is recommended to ensure structural stability and reduce the risk of breakage. Diameters below 0.8 mm should be avoided unless reinforcement is planned as part of a post-processing step.

Bridges with Large Spans
In DMLS, a bridge is a flat, downward-facing surface supported by two or more features. Due to the rapid heating and cooling cycles in the manufacturing process, excessively large unsupported spans can result in poor-quality downward-facing surfaces. Bridge spans should be limited to 2 mm. Longer spans should include additional supports or slight curvature to distribute stress and reduce warping.

Adjacent Elements
During DMLS, the laser creates a melt pool that is slightly larger than the laser beam diameter. This can cause closely spaced elements to fuse together or entrap unsintered powder between printed sections. To prevent unwanted fusion, a minimum gap of 0.5 mm should be maintained between elements. Moving parts should also have a minimum gap of 0.5 mm, while press fits require at least 0.3 mm. A clearance of at least 0.6 mm is necessary for printing linkages.

Escape Holes in Hollow Parts
Hollowing out parts significantly reduces material consumption and weight without compromising functionality. However, it is essential to design adequate escape holes to remove unsintered powder from internal cavities. Escape holes should have diameters between 2 mm and 5 mm and should be placed on non-visible surfaces. Avoid clustering escape holes together; instead, distribute them near edges or on opposite sides of the component.