The build orientation choice for an assembly feature such that primary loads run parallel to XY layers, not through the weaker Z inter-layer bonds.
FDM parts exhibit anisotropic strength: XY ~100% of material tensile strength, Z ~60–80% due to interlayer adhesion. A snap-fit arm, living hinge, or press-fit boss loaded in Z may fail at 60% of the design load. SLS and SLA are near-isotropic, so orientation is less critical for strength.
Snap-fits: deflection axis in XY. Bolted bosses: bolt axis along Z (compression is isotropic; tension uses the full thread form printed in XY). Living hinges: axis parallel to Y so layers run along the bend. Press-fit pins: pin axis in Z for roundest cross-section.
Rotating 90° for strength may expose other surfaces to support scarring, worsening fit accuracy. Always weigh the trade-off. For DMLS: residual stress from Z-direction solidification can distort overhanging assembly features. For SLS: downward-facing holes accumulate unsintered powder.
Related terms: Snap-fit design, Living hinge, Press-fit joint, Clearance for moving / mating parts
| Theme | assembly |
|---|---|
| Also called | load-aligned joint, build direction assembly |
| Source | sources/2026-04/2026-04-30--fdm-starterpack-bg |
Engineer, author of The Big Book of 3D Printing and additive manufacturing expert