Inframotion 3D publishes SLS design rules covering walls, powder escape and tolerances

Inframotion 3D, a supplier of SLS powders compatible with several printer ecosystems, has released a design guide for selective laser sintering. It lists the geometry rules that matter most, from wall thickness to powder escape, and stresses that all values are starting points to be confirmed for the exact powder and machine.

Context Powder escape means openings that let unsintered powder leave enclosed cavities after the build.

Why SLS allows freer geometry

The surrounding powder bed carries the part during the build, so no support structures are needed. Enclosed channels, lattices, undercuts and nested assemblies are therefore realistic options, and the process suits functional parts as well as prototypes. Heat shrinkage, powder packing and laser energy still influence accuracy, surface quality and warping, and the safe design window shifts between PA12, PA11, glass-filled nylon and TPU.

Orientation, warping and tolerances

Orientation determines strength direction, surface appearance, dimensional stability and which faces hold critical fits. Large flat areas and long thin spans tend to distort. Tilting the part, interrupting flat faces, adding ribs or lattice reinforcement, or splitting oversized parts can lower that risk. The guide cites an early planning figure of about plus or minus 0.3 mm, or 0.3 percent of nominal length, but calls it guidance only. Holes and mating features need allowance, reaming or machining suits tight bores, and critical assemblies should be checked with coupons or a first article.

Lowering build cost

Grouping similar parts and choosing orientations that use the chamber well helps throughput. Hollowing, shelling or lattices cut weight and powder use, provided the part still empties cleanly. Cosmetic finish demands and extra machining add cost without function. Designs that depowder consistently also support better powder refresh and reuse economics.

What it means

For small and mid sized manufacturers, the guide is a useful checklist but not a qualification document. Its tolerance figure is explicitly a planning value, so parts with tight fits still need first article checks on the actual powder and machine, which adds time and cost. Designing for clean depowdering and sensible nesting is the cheapest lever on cost per part, and it needs no new equipment, only design skills.

Frequently asked questions

Does SLS need support structures?

No. The surrounding powder bed holds the part during the build, which makes channels, lattices and undercuts easier to realise.

What tolerance does the guide suggest for SLS?

About plus or minus 0.3 mm or 0.3 percent of nominal length as an early assumption, not a guarantee. Real accuracy depends on machine, powder and build conditions.