TL;DR

Excessive dross is most often a speed or cut height problem. Reduce speed for top dross and increase speed for bottom dross. Always re-check standoff after changing cut parameters.

What you might see

heavy dross attached to bottom edge of cut
top edge spattering or bead formation
cut parts require excessive grinding to clean up
dross intermittently bridges the kerf

Likely causes

Tap to mark as ruled out

Cut speed too slow causing molten metal to re-solidify below the cut (slow-speed dross)
Cut speed too fast causing blow-back and bead on the top edge
Cut height too high stretching the arc and widening the heat affected zone
Worn consumables producing an irregular arc column

Required tools

Hypertherm cut chart for the material being cut
Standoff gauge or torch height control readout
Scrap material of same type and thickness
Electrode pit gauge or digital caliper

Safety first

Dross removed by grinding is sharp and can reach high temperatures. Wear leather gloves and face shield during cleanup.
Plasma arc UV radiation requires a shaded welding lens. Never look directly at the arc without appropriate eye protection.

Procedure

7 steps · ~30 min

1
Identify the dross type. Bottom dross that is hard and adhered indicates too-slow cut speed. Top edge bead indicates too-fast speed.
2
Consult the Hypertherm cut chart for the material type and thickness being cut. Note the recommended speed and amperage range.[1]
3
Verify the standoff height using a cut height gauge or torch height control readout. Standoff within the recommended range reduces dross significantly.[1]
4
If bottom dross is present, increase cut speed by 10 percent increments until dross decreases, testing on scrap each time.
5
If top edge bead is present, reduce cut speed by 10 percent increments.
6
Inspect consumables and replace if the electrode pit depth exceeds 1.5 mm. Worn consumables produce irregular dross regardless of parameters.
7
For mechanized cutting, confirm the torch height control sensor and drive are maintaining consistent standoff throughout the cut.

Sources

Hypertherm Hypertherm Powermax 65 / 105 / 125 Plasma Cutting System general technical documentation, Hypertherm
Hypertherm Powermax 65 / 105 / 125 cut quality guide and operator manual (general)

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