Direct metal laser sintering (DMLS) is not intended to replace traditional metal manufacturing like casting, metal injection molding, or machining. Rather, it’s a product development tool that opens up new design possibilities. Product designers and engineers commonly rely on metal 3D printing to manufacture complex geometries, reduce the number of components in an assembly, or even lightweight objects.
Here’s a look at how to design 4 common features found in metal 3D-printed parts.
1. Self-Supporting Angles
A self-supporting angle describes the feature’s angle relative to the build plate. The lower the angle, the less the likely it is to support itself.
Each material will perform slightly different, but the general rule of thumb is to avoid designing a self-supporting feature that is less than 45 degrees. This tip will serve you well across all available materials. As you can see in the picture above, as the angle decreases, the part’s surface finish becomes rougher and eventually the part will fail if the angle is reduced too far.
Overhangs differ from self-supporting angles in that they are abrupt changes in a part’s geometry—not a smooth slope. DMLS is fairly limited in its support of overhangs when compared to other 3D printing technologies like stereolithography and selective laser sintering. Any overhang greater than 0.020 in. (0.5mm) should have additional support to prevent damage to the part. When designing overhangs it is wise to not push the limits as large overhangs can lead to reduction in a parts detail and worse, lead to the whole build crashing.
3. Channels and Holes
Internal channels and holes are one of the primary benefits of DMLS since they are impossible with other manufacturing methods. Conformal channels provide even cooling throughout a part and aid in reducing a component’s weight.
It’s recommended that channels do not exceed a diameter of 0.30 in. (8mm). Similar to unsupported structures, as you exceed 0.30 in., the downward facing structures will become distorted. A tip to work around this constraint is to avoid designing circular channels. Instead, design channels with a tear drop or diamond shape. Channels that follow these shapes will make for a more uniform surface finish within the channel and allow you to maximize the channel’s diameter.
A bridge is any flat down-facing surface that is supported by 2 or more features. The minimum allowable unsupported distance we recommend is 0.080 in. In relation to other 3D printing technologies, this distance is relatively short due to the stresses of the rapid heating and cooling. In the picture below, you will see how the bridge pulls in the supporting structures as the unsupported distance increases. Parts that exceed this recommended limit will have poor quality on the downward facing surfaces and not be structurally sound.
Learn More About Metal 3D Printing Design
If you would like to learn more about how to design for DMLS and metal 3D printing in general, check out our webinar “Designing for DMLS.” You’ll find more details and tips on how to optimize your part design for metal 3D printing, select the right material, and reduce multi-part assemblies. Click here to view the on-demand webinar.
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