How to Fix PLA Warping
PLA shrinks so little that it prints flat on an open printer in a chilly room — which is exactly why PLA warping deserves attention. When the easiest material lifts its corners, something specific is wrong, and it is nearly always one of four things.
The four causes of PLA warping
In rough order of likelihood: a greasy or worn plate surface, cold air moving across the print (drafts, or the auxiliary fan on enclosed machines), a bed temperature outside PLA’s window, and finally geometry — huge flat parts with razor-sharp corners can defeat even PLA’s low shrinkage.
Fixes in order
1. Wash the plate. Dish soap, warm water, clean towel, touch only the edges afterwards. Fingerprint grease weakens the bond exactly at the corners where shrink stress concentrates. This fixes the majority of “my PLA suddenly warps” cases outright.
2. Set the bed to 55–65 °C. Bambu’s stock PLA profile uses 55 °C on textured PEI (the Cool Plate variant runs 35 °C). If corners lift, nudge up toward 60–65 — but never past 65: PLA softens at about 45 °C, and a hotter bed turns the bottom rubbery and causes elephant foot instead. Vendor defaults across the industry sit in the same band, from 45 °C (Anycubic) to 65 °C (Sovol).
Filament settings → Filament (bed temperature row for your plate)3. Check what’s blowing on the print. PLA runs its part fan flat out (100 %) and tolerates it — that is not the problem. The problem is asymmetric airflow: on enclosed machines with a side-mounted auxiliary fan, the stock PLA profile runs that fan at 70 %, and prints that always lift on the same side are feeling it. Drop the auxiliary fan to 30–40 %. On open printers the equivalent culprit is a draft: an open window or AC vent warps the facing side.
Filament settings → Cooling → Auxiliary part cooling fanFor large, flat parts
- Brim: outer brim,
8 mm, for anything plate-filling or thin-cornered. PLA’s shrink force is low enough that a brim nearly always wins. - First layer quality: a corner that warps late usually bonded weakly early. Slow the first layer to
20 mm/sand check the PLA first layer guide if the bottom looks patchy. - Rounded corners: a few millimetres of fillet in CAD halves the stress concentration at each corner — cheaper than any setting.
What you should not need
Glue sticks, hairspray, rafts and enclosures are all overkill for PLA on a modern PEI plate — if you find yourself reaching for them, something upstream is wrong: the plate is worn (textured PEI does eventually lose grip after years of cycles), the “PLA” is a blend behaving like something else, or the real problem is adhesion rather than shrinkage. A part that detaches entirely rather than lifting at corners is an adhesion failure — see PLA bed adhesion. For cross-material warping theory, the main warping guide covers chambers, materials and fan strategy in one place; day-to-day PLA values live in the PLA settings guide.
Frequently asked questions
Why is my PLA warping?
In rough order of likelihood: a greasy or worn plate surface, cold air moving across the print (drafts, or the auxiliary fan on enclosed machines), a bed temperature outside PLA’s window, and finally geometry — huge flat parts with razor-sharp corners. Washing the plate with dish soap and warm water fixes the majority of “my PLA suddenly warps” cases outright.
What bed temperature stops PLA warping?
Set the bed to 55–65 °C. Bambu’s stock PLA profile uses 55 °C on textured PEI; if corners lift, nudge up toward 60–65 °C — but never past 65, because PLA softens at about 45 °C and a hotter bed turns the bottom rubbery and causes elephant foot instead. Also check the auxiliary fan: dropping it from the stock 70 % to 30–40 % fixes prints that always lift on the same side.
Do I need glue or an enclosure to print PLA flat?
No — glue sticks, hairspray, rafts and enclosures are all overkill for PLA on a modern PEI plate. If you find yourself reaching for them, something upstream is wrong: the plate is worn, the “PLA” is a blend behaving like something else, or the real problem is adhesion rather than shrinkage. For large flat parts, an 8 mm outer brim and a 20 mm/s first layer are enough.
Not sure which of these fixes applies to your print?
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- Printed Model Warping: Causes and Solutions — Bambu Lab Wiki
- Introduction to Bambu Lab 3D Printer Fans — Bambu Lab Wiki
- OrcaSlicer vendor profiles — SoftFever/OrcaSlicer (GitHub)