Falcon 10 Watt 4 mm MDF cutting problem

Hi,
i am a n owner of an falcon 10W and tried to cut some 4mm MDF.
Program: Lightburn
Settings: 300mm/s - 100% - 3 rounds
The distance between the Laser and the MDF is the lowest step on the enclosed measuring gauge.
My Problem is, as you can see in the picture, that the cuts are sometimes deep enough and kind of repeating not.

I already tried less speed and more rounds but it just result in more burned wood, not deeper cuts xD.

Hope someone can help me :slight_smile: