Lattice structures

1. Introduction: Bionics in 3D printing

When engineers strive for maximum stability with minimum weight, they often look to nature. The interior of our bones (trabeculae) or bird bones is not made of solid material, but of a sponge-like lattice structure (lattice). These structures transmit forces extremely efficiently, are light and can absorb energy.

Classic manufacturing processes cannot produce such complex internal grids. Powder bed-based metal 3D printing (such as PBF-LB or EBM), on the other hand, handles lattices effortlessly. This white paper highlights the potential and pitfalls of lattice structures.

2. Types of lattice structures

Not every grid is the same. There are roughly two main families:

• Strut-Based Lattices: Examples are BCC (Body-Centered Cubic), Octet or Diamond Lattices. They resemble half-timbered structures. They are extremely predictable and dissipate forces well.
• TPMS (Triply Periodic Minimal Surfaces): Examples are the Gyroid or the Schwartz-P. They are based on complex mathematical equations and have no sharp edges or knots, but consist of continuously curved, extremely thin walls. They are structurally superior because they have no stress peaks (notch effect) at junction points.

3. Revolutionary areas of application

Grid structures offer properties that solid metal can never have.

• Medical technology (osseointegration): Titanium implants (hip sockets, spinal cages) are printed with roughened BCC or trabecular grids. The bone can physically grow into the implant. In addition, the stiffness of the implant can be precisely adjusted to the stiffness of the real bone using the grid, which prevents the "stress shielding" effect (bone loss).
• Heat exchanger: TPMS grids (like the Gyroid) perfectly separate two volumes in the room and offer a gigantic surface. If you pump hot fluid through one cavity and cold fluid through the other, you get the most efficient heat exchanger in the world.
• Crash absorber: In the automotive sector, lattice structures can be constructed in such a way that the struts specifically buckle in the event of an impact (buckling) and thereby dissipate enormous impact energy.

4. The limits of the grid illusion

Despite the euphoria, lattices pose enormous challenges in the powder bed process.

• Depowder removal: A closed component with a lattice core is useless if the trapped residual powder cannot be removed. Sufficient powder outlet holes must be constructed and the component must be rotated and evacuated on shaking tables, sometimes for hours.
• Data volume: A component with millions of small struts exceeds the storage capacity of the classic STL format (the file becomes hundreds of gigabytes in size). Modern CAD software therefore exports lattices as mathematical metadata (slices or special CLI formats).
• Support and Construction Angles: Strut grids must be designed so that each strut is at an angle of over 45 degrees to the build plate (self-supporting), otherwise the structure will collapse during printing or require irremovable support structures inside.

5. Conclusion: Geometry as a material

With lattice structures, the form itself becomes the material. The designer no longer just chooses between “aluminum” or “titanium”, but between “solid aluminum” and “aluminium gyroid with 30% density”. Lattices are the absolute key to the ultimate lightweight solutions in the aerospace and medical technology sectors.