Support Structures: Construction and Removal
The biggest cost driver in the PBF-LB process and how to avoid it through clever DfAM.
1. Introduction: The necessary evil
One of the biggest myths in 3D printing is “complexity for free.” The image of a component magically floating out of the powder bed is deceptive. In reality, powder bed-based processes (PBF-LB) require massive support structures for almost any complex geometry.
Support structures eat expensive metal powder, dramatically increase print time, and removing them manually incurs huge post-processing costs. This white paper shows why supports are necessary and how clever design minimizes them.
The 45 degree rule
The basic rule in the LPBF process is: Overhangs and areas whose angle to the building board is less than 45 degrees (downskin areas) must be supported. Otherwise, the melt will sink into the loose powder below (the powder does not support), resulting in coarse surfaces (Dross formation) or direct construction demolition.
2. The real job of support
In metal 3D printing, support has a much more important task than just protecting the component from gravity.
- Heat dissipation: The laser generates thousands of degrees of heat. When it passes over loose powder (which is an excellent insulator), the heat builds up. The melt pool virtually explodes. Solid support structures act like cooling fins: They dissipate the extreme heat from the overhang downwards into the solid building plate.
- Warping prevention (anchoring): The rapidly cooling layers contract extremely (shrinkage) and generate internal stresses that tend to bend the component upwards. Solid block supports anchor the component to the plate using brute force to prevent it from tearing off.
3. Types of support structures
Designers can choose different support types in the software (e.g. Materialize Magics):
- Block Support: Grid-like box structures. Very strong, dissipates heat great, but difficult to remove. Is usually used as an anchor for the component base.
- Tree support (tree structures): Organically growing branches that support the component at specific points. They save a lot of powder and are easy to break off, but dissipate heat more poorly.
- Cone support: Small cones that rest on the component surface to keep the contact surface minimal (easy to break off).
4. Design for Additive Manufacturing (DfAM)
The best support is the one you don't have to print. Thanks to intelligent DfAM, the design is designed to be support-free.
- Teardrop shapes: Circular holes and horizontal cooling channels are often constructed as lying drops or in diamond shapes. The steep sides (over 45 degrees) support themselves.
- Orientation: A flat component that lies parallel to the plate needs 100% support. If you rotate it by 45 degrees in the installation space, it suddenly supports itself.
5. Conclusion: Cost driver No. 1
Anyone who leaves the design of support structures to the software machine will pay a fortune in production. Solid titanium supports require milling, band sawing or wire erosion (EDM) to remove them. A master AM designer invests more time in the smart, support-free alignment and shaping of the component than in the actual CAD design.