Cooling Decoded: Matching Fan Speed to PLA, PETG, ABS and TPU for Crisp Overhangs

Two printers running the same filament can produce very different parts, and more often than not the difference is cooling. The part-cooling fan is easy to ignore — it is off by default in many profiles and tempting to set to 100% and forget. But each material has its own rules, and getting them wrong produces either drooping overhangs or parts that crack and delaminate. This guide breaks down cooling the way the slicer sees it, material by material.

What the part-cooling fan actually controls

The fan blows air onto the freshly extruded layer to solidify it quickly. Faster cooling means crisper bridges and overhangs and less stringing, because the softened plastic is locked into shape before it can sag. The catch is that aggressive cooling weakens layer adhesion: if each layer cools and shrinks too fast, it pulls away from the layer below it, risking warping and cracks on materials that shrink a lot.

Why material matters

• Semi-crystalline and flexible materials like PETG and TPU do not need — and often cannot handle — aggressive cooling.
• High-shrink materials like ABS must stay warm or they warp and delaminate.
• Low-shrink materials like PLA love strong cooling for clean overhangs and surfaces.

The result is that the right fan speed is a property of the filament, not a universal setting.

Material-by-material cooling rules

Stepping through a reliable setup

1. Start with the material preset

Modern slicers ship good starting fan curves per material. Don't override them before you know why. Load the correct profile, then tune only what your environment demands — a hot room or an open, drafty space shifts the balance.

2. Use a fan curve, not a fixed value

Good profiles ramp the fan in slowly over the first few layers, keeping the base firmly bonded to the bed before cooling ramps up. For PETG and TPU especially, the first layers should run with little or no fan to guarantee strong adhesion.

3. Tune overhangs and bridges separately

If overhangs droop, your fan speed or minimum layer time is too low for that geometry. Raise the fan's overhang threshold setting (the angle at which the slicer boosts cooling) rather than cranking global cooling, which would hurt other features. For PETG's string-prone nature, slow down and reduce retraction distance instead of adding more cooling.

For PLA prints where you want maximum overhang crispness, ANTINSKY PLA+ Filament 1.75mm runs beautifully at high fan speeds with low warp risk. If you need a tougher everyday material that tolerates moderate cooling, ANTINSKY PETG is a dependable pick — just keep that fan in the 20-50% band. For enclosed, high-temperature jobs, ANTINSKY ABS is best printed with the fan off or barely on. And when you want soft-touch, flexible parts, ANTINSKY TPU 85A prints best with gentle cooling and a slower feed rate.

Warning signs your cooling is wrong

• Drooping, sagging overhangs → not enough cooling (or too fast at that geometry).
• Corners lifting, cracks between layers (ABS) → too much cooling, need an enclosure.
• PETG layers splitting or glossy-to-matte inconsistency → too aggressive cooling.
• TPU blobbing or weak, stringy parts → cooling or speed out of balance.

Wrap up

Cooling is a dial, not a switch, and each filament family lives in a different part of the range. Match the fan to the material — fast and strong for PLA, gentle for PETG and TPU, off-and-warm for ABS — and you will solve a surprising share of your surface-quality problems without changing a single hardware part. Pair that knowledge with the right spool and your overhangs will finally print as clean as the model promises.

Need the right material for your cooling conditions? Browse ANTINSKY PLA+, PETG, ABS and TPU at InnoStation 3D.