Small bumps on flat surfaces when printing PLA

[Yves_K 0]

Has anybody seen this behaviour when printing flat surfaces with PLA, does it comes from the filament, from the print head or from the heated plateau ?

This happened on two different prints.

 

Thank you in advance

[glx 23]

How many top layers did you use? That effect is called pillowing, it comes from the layers on top of the infill not nicely bridging over the infill gaps. You can usually get rid of it by just adding more top layers and/or increasing the infill. Alternatively you can lower the printing temperature, slow down the print speed for the top layers and/or increase the amount of cooling. 

[Yves_K 0]

Great, Thanks !

To be honest, I have not checked the top layers thickeness/number nor the infill, I just used the "by default" recommendations of Cura. I will check both as well as the temperature and also increase the infill when going up.

Thank you again