A thin, flexible section of material connecting two rigid parts that acts as a hinge through repeated flexure without mechanical fasteners.
Living hinges rely on fatigue resistance of the hinge material. Polypropylene (PP) is the classic material: withstands millions of cycles. For FDM: TPU (shore 95A–85A) and flexible PETG are good candidates. Critical dimension: hinge thickness t = 0.3–0.8 mm; width w ≥ 5 mm for lateral stability.
Print living hinges with layer lines running perpendicular to the bend axis for maximum fatigue life (XY plane, hinge parallel to X-axis → layer lines in X → flexure in Z-direction = worst case; reorient to hinge in Y). Anneal PP hinges after printing for crystallization.
PLA and ABS living hinges fail quickly (< 100 cycles typical) due to brittleness. FDM layer orientation at the hinge is critical: interlayer cracks initiate rapidly under bending. Use TPU or PP for functional hinges. Never rely on FDM rigid material hinges in products.
Related terms: Snap Fit, Part Consolidation, DfAM (Design for Additive Manufacturing), Minimum Feature Size
| Field | engineering |
|---|---|
| Also called | flex hinge, integral hinge, film hinge |
| Source | EDi Brain: rules-core |
Engineer, author of The Big Book of 3D Printing and additive manufacturing expert