Dross mostly appears on the bottom surface, indicating that molten metal has not been fully blown away.

Adjustment sequence: 1) Focus: Lower the focus first (-1 to -2 mm) and observe whether dross decreases. 2) Speed: Reduce speed appropriately, but too slow a speed leads to excessive heat input and more severe dross. 3) Gas pressure: Insufficient nitrogen cutting pressure is a common cause; for 6 mm plate, 14-16 bar is recommended; excessive pressure creates turbulence. 4) Nozzle: Check concentricity and orifice diameter; nozzle wear causes airflow deflection. 5) Material: Confirm the surface is free of oil and rust, otherwise absorption is affected.

Change only one parameter at a time and record cut quality to avoid mixing multiple variables.