Standard SLS tolerances at our shop: ±0.15 mm on dimensions up to 100 mm, ±0.2-0.3 mm on 100-300 mm, ±0.3-0.5 mm above. Depends on geometry, orientation and material. For tighter (±0.05 mm) on critical zones: CNC finishing. Fibre-reinforced materials (Carbon LW, PA802CF) have light anisotropy.
What sets the tolerance
Four factors.
Part size – Larger = more thermal shrinkage and variation.
Wall thickness uniformity – Strongly varying thicknesses shrink differently on cool-down.
Orientation – Horizontal dimensions are usually a touch more accurate than vertical.
Material – PA12 is the most predictable. Fibre-reinforced materials like Carbon LW and PA802CF have light anisotropy, so strength and shrink vary per direction.
How to get tighter tolerances
For tolerance-sensitive zones (press-fits, gears, bearing fits): CNC finishing hits ±0.05 mm or better. We offer this as an optional step after SLS printing.
Alternative: model oversize on critical zones (e.g. +0.3 mm) and mill it. For thread joints: heat-set inserts (metal in polymer) instead of tapped threading.
Our engineers advise which zones justify tolerance optimisation and which you can keep within SLS tolerance.
What we guarantee during production
Per production batch: sample checks on critical dimensions. For large runs we recommend a pilot batch of 20-100 pieces. Catches orientation effects and print-to-print variation before you place a large order.
For certified applications (medical devices, food contact): Certificate of Analysis per batch with sample measurements and material lot traceability. Your quality team integrates our measurement results into incoming inspection.