Pillowing and holes in the top surface
The top surface is bumpy, has gaps, or you can see the infill pattern through it.
Also described as holes in top, top layer gaps, bumpy top, infill showing through, pillow, rough top surface, top not closed
Try these in order
Most likely and quickest to check first. Change one thing at a time so you know what fixed it.
Not enough top layers
- Use at least 0.8 to 1 mm of top layers (four or five layers at 0.2 mm).
- Raise infill density a little, say from 10 to 15%, so the top layers have more to sit on.
Not enough cooling
- Turn the part cooling fan up to 100% for PLA top layers.
Under-extrusion
- Calibrate the flow rate. Gaps in the top layer often show slightly low flow first.