The strength of the bond formed between successive deposited layers during FDM printing.
Layer adhesion in FDM arises from thermal diffusion: the hot incoming filament partially remelts the layer below, allowing polymer chains to interdiffuse across the interface. Bond strength is governed by print temperature, layer height, and cooling rate. Higher temperatures and slower cooling promote deeper chain entanglement, improving Z-axis tensile strength, which typically reaches only 20-50% of XY-plane strength.
Increase nozzle temperature by 5-10 C to improve adhesion on difficult filaments. Reduce part cooling fan speed for the first few layers. Keep layer height at 50-75% of nozzle diameter for adequate melt overlap. Post-processing with acetone vapour (ABS) or annealing can further consolidate interlayer bonds.
Over-cooling kills adhesion: a fan set too high on ABS or PETG causes delamination under load. Insufficient temperature produces visible layer separation and catastrophic Z-crack failures. Contaminated or wet filament introduces steam voids that act as stress concentrators.
Related terms: Retraction, Print Speed, Part Cooling, Filament Drying
| Field | 3D printing, mechanics |
|---|---|
| Also called | interlayer bonding |
| Source | EDi Brain: tech/fdm |
Engineer, author of The Big Book of 3D Printing and additive manufacturing expert