Weak layer adhesion — where printed layers split or peel apart — is usually caused by too-low print temperature, excessive part cooling, high speed, or wet filament. Each weakens the bond between layers. Diagnose by where and how it splits, then fix the matching cause. Here is the full guide to stopping delamination.
Key Takeaways
- Delamination = layers not fusing fully.
- Main causes: low temp, too much cooling fan, high speed, wet filament.
- FDM parts are weakest along the layer (Z) axis — design and orient for it.
- Fixes: raise temp, reduce cooling for high-temp materials, slow down, dry filament.
- For isotropic strength, SLS or metal removes the weak-axis problem.
What causes weak layers?
Each layer must partially re-melt the one below to weld to it. If the plastic is too cool, moving too fast, or chilled by the fan, the weld is incomplete and the bond is weak. Wet filament sputters and leaves voids. The result: a part that snaps cleanly along a layer line under load.
How do you fix it?
| Cause | Fix |
|---|---|
| Too cool | Raise nozzle temp 5–10 °C |
| Over-cooling | Reduce fan for ABS/nylon/PC |
| Too fast | Slow print speed |
| Wet filament | Dry before printing |
| Thin layers on tall parts | Increase layer height/width |
Design around the weak axis
Even a perfectly tuned FDM part is weaker along the layer axis. Orient parts so loads run along, not across, the layers — see design for FDM strength. When strength must be equal in all directions, SLS nylon and metal are effectively isotropic.
When to outsource
For load-bearing parts that must not delaminate, Layer X tunes per material and can switch you to SLS or metal for isotropic strength. Send your part.
Frequently Asked Questions
My part snaps along a layer — why?
That is classic weak Z-axis adhesion. Raise temp, slow down, dry filament — or reorient/switch process.
Does infill fix weak layers?
Infill adds internal strength but won''t fix a poor layer weld — address the bond first. See infill patterns.