A lattice is a repeating three dimensional unit cell used to fill a volume with a controlled fraction of material. Printing makes them buildable for the first time, and that has produced both genuinely valuable engineering and a great deal of decoration. The difference is whether the lattice was chosen for a mechanical purpose or because the software offered it.
The types and what they do
Strut based lattices, built from beams meeting at nodes, are efficient in stiffness per unit mass and concentrate stress at the nodes. Surface based lattices, built from smooth continuous surfaces, distribute stress far better and are much better in fatigue. Stochastic foams mimic natural cellular structures and are good at absorbing energy. Which family you choose should follow from whether the requirement is stiffness, energy absorption or surface area.
What lattices are genuinely for
Reducing mass where mass costs money for the whole life of the product, which is why aerospace uses them. Absorbing energy in a controlled, tunable way, as in helmet liners and protective padding. Maximising surface area in heat exchangers and catalyst supports. And producing a porous surface that bone will grow into, which is a major medical implant application.
The manufacturing constraints
Every strut is an overhang, so the cell orientation relative to the build direction decides whether it prints cleanly. Fine lattices trap unfused powder or uncured resin that must be able to escape, so drain paths are a design requirement. And a lattice inside a closed volume that cannot be cleared is a part that cannot be certified, however good the simulation looked.
When it is a gimmick
When it replaces solid material in a part that was not mass critical. When it is applied to a surface for appearance and then has to be inspected. When the load path is not understood, since a lattice is only efficient in the directions its cells are efficient in. And whenever nobody can state which property the lattice is improving and by how much.
Questions people ask about lattice structure 3d printing
What is a lattice structure?
A repeating three dimensional unit cell used to fill a volume with a controlled fraction of material, in order to trade mass against stiffness, energy absorption or surface area.
Which lattice type should I use?
Strut based for stiffness per unit mass, surface based for fatigue and even stress distribution, stochastic foams for energy absorption.
What is the main manufacturing problem?
Getting unfused powder or uncured resin out. A fine lattice inside a closed volume that cannot be cleared is not a manufacturable part.
When is a lattice not worth it?
Whenever nobody can say which property it improves and by how much. If the part was not mass critical, a lattice usually adds cost and inspection difficulty for nothing.