How to Fix Layer Separation and Delamination

Layer separation, also called delamination, is when printed layers split apart or crack along a layer line. Prusa describes it as the de-lamination of printed layers, mostly caused by wrong temperatures or too much cooling from the print fan or the surrounding air. A part can crack during the print or snap along the layers when stressed.

Prusa's Knowledge Base explains the mechanism: the object cracks when layers cool at different rates and the warping forces exceed the layer adhesion strength. So every fix either keeps layers hotter, shields them from cold air, or reduces the pull of shrinkage.

Symptom table

1. Raise the nozzle temperature

Prusa notes that PLA may suffer from cracking and layer separation if it is printed with insufficient temperature, and that depending on the brand PLA is printed between 195 and 220 °C. Its advice is to try increasing the printing temperature in 5 °C increments until layer adhesion is good. Stay inside the range printed on your spool, and see PLA print temperature and PETG print temperature for ranges.

Hotter plastic also strings more, so make small changes and check for stringing after each step.

2. Control cooling and drafts

Prusa states that ABS is highly susceptible to layer separation when any cold air blows on the print before it has cooled fully, and recommends turning the fans off for ABS prints completely. It also suggests printing ABS in an enclosed chamber. Read enclosed vs open-frame 3D printers if you are deciding whether you need one.

For other materials, remember that the part cooling fan trades surface quality against layer bonding. If a part is weak between layers, try lowering fan speed in the filament profile, then re-check overhangs.

3. Pick a more forgiving material for large parts

Prusa notes that you may not be able to print objects covering the whole print area in ABS, and suggests replacing it with PETG. In its words PETG has similar advantages to ABS, but is much better for printing large objects and does not have the same tendency to crack or delaminate. It also names ASA as a good alternative that depends more on a stable environment. Compare options in types of 3D printer filament. If your problem is specifically ABS, see how to fix ABS cracking.

4. Increase the flow rate slightly

Prusa's guide says that more material extruded creates a stronger bond between layers, and suggests raising the flow rate (called the extrusion multiplier in PrusaSlicer) in 5% steps. Only do this after you have checked temperature and cooling, because high flow can cause bulging, ridges and dimensional errors. See over-extrusion for the opposite problem.

5. Keep the part stuck down and avoid warping

Bambu Lab's wiki explains that when a corner lifts, the nozzle to part gap shrinks and extra filament squeezes out sideways, which creates bulges. Its suggestions include cleaning the build plate, enabling a brim or brim ears, and slightly raising the plate temperature. For enclosed printers it advises keeping the front door and top cover closed to stabilize chamber temperature. Related reading: fix warping and fix a bad first layer.

6. Check the filament

Wet filament bubbles and extrudes unevenly, which weakens bonding. If you hear popping or see rough surfaces, try drying the filament. Bambu's wiki also suggests checking that the filament diameter is consistent, quoting 1.75 mm plus or minus 0.02 mm.

Test the fix

Print a small hollow box or a tall thin-walled cylinder, 40 to 60 mm high. Try to break it by hand along the layers after each change, or twist it gently. If it splits cleanly along a layer, the bond is still weak. Change one setting per test and keep notes.