Warping in 3D printing: when the corners lift off the bed

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With warping, the corners of a print bend upwards and come away from the print bed. Sometimes it is only a millimetre or two at one corner, sometimes the whole part tears loose. Particularly annoying: it often only happens after hours, when many layers have already been printed.

Why does the print warp?

Plastic shrinks as it cools. Each new layer is laid down hot and contracts as it cools. In doing so it pulls on the layers beneath. This force is greatest at the corners, and if it is stronger than the adhesion to the bed, the corners lift.

It follows that the more a material shrinks and the greater the temperature difference between the print and the surroundings, the more warping.

Which materials are affected?

With PLA, warping is usually a sign of an adhesion problem. With ABS, ASA, nylon or PC, on the other hand, it is mainly a question of the environment.

What helps, ordered by effect

1. Warm, draught-free environment

The most important lever for engineering materials. An enclosed printer keeps the heat from the print bed in the build volume. Printers with an actively heated chamber go even further. Let the chamber preheat for a few minutes before printing.

With an open printer, an enclosure helps, and if need be even a cardboard box over the machine. Above all it matters that there are no draughts, no open window and no air conditioning nearby.

2. Good adhesion to the bed

• Clean the build plate thoroughly, ideally with washing-up liquid and water
• Bed temperature suited to the material, 90 to 110 °C for ABS and ASA
• With nylon and PC, a thin film of glue stick on the plate often helps
• First layer pressed down sufficiently (check the Z offset)

3. Enable a brim

A brim is a flat border around the part in the first layer. It enlarges the adhesion area exactly where the forces are greatest. A width of 5 to 8 mm is usually enough. Afterwards it can be peeled off.

4. Less part cooling

With ABS, ASA and PC, strongly reduce the part cooling fan or switch it off entirely for the first layers. The manufacturer profiles in the slicer usually already do this correctly.

5. Adapt the design

If you design the model yourself:

• Round off sharp corners, as this spreads the stress
• Avoid large, flat surfaces where possible or split them up
• If needed, print small round discs at the corners as well (“mouse ears”)

Quick checklist

1. Material prone to shrinking (ABS, ASA, PA, PC)? Then print enclosed.
2. Plate clean, bed temperature suitable?
3. Brim enabled?
4. Fan reduced for this material?
5. No draughts in the room?

If none of this helps, it is worth taking a look at the first layer. Which printers have an enclosed or heated chamber you can see in the printer comparison.