Ironing is a slicer feature for flat top surfaces. After the normal top skin is printed, the nozzle makes an additional pass at the same layer height with a very small amount of extrusion to flatten high spots and fill shallow valleys.
How do you recognize it?
- Smoother top surfaces when tuned well
- Grooves remain when coverage is too weak
- Smeared or rough surfaces when flow is too aggressive
Common causes
- Underlying top skin is not good enough
- Ironing flow/spacing/speed are not matched to the material
- Nozzle contamination or prolonged thermal exposure
What should you check first?
- Tune the normal top surface first.
- Calibrate ironing flow before changing many variables at once.
- Use realistic test parts, not only tiny coupons.