Laser cutting Problems DROSS

Hello everyone,

i am using a bystronic laser cutter. i have been told that for cutting thicker mid steel oxygen pressure should be reduced.
whenever i reduce the pressure i can get a good cut on the outer profile of the part by any smaller holes and slots are very drossy. i can overcome this by setting my press higher for example im cutting 8mm mild steel with 1 bar of oxygen press which just seems to high..

Any help welcome,

Thanks,
David