Hypertherm HRT2 - Manual (Page 55)

OPERATION
Duramax Retrofit Torch
Operator Manual
3-25
Dross
Some amount of dross will always be present when cutting with air plasma. However, you can minimize the amount and
type of dross by adjusting your system correctly for your application.
Excess dross appears on the top edge of both pieces of the plate when the torch is too low (or voltage is too low when
using a torch height control). Adjust the torch or adjust the voltage in small increments (5 volts or less) until the dross is
reduced.
Low-speed dross forms when the torch’s cutting speed is too slow and the arc angles ahead. It forms as a heavy,
bubbly deposit at the bottom of the cut and can be removed easily. Increase the speed to reduce this type of dross.
High-speed dross forms when the cutting speed is too fast and the arc angles behind. It forms as a thin, linear bead of
solid metal attached very close to the cut. It is more firmly attached to the bottom of the cut than at low speed and is
difficult to remove. To reduce high-speed dross:
• Decrease the cutting speed.
• Decrease the torch-to-work distance.
Note: Dross is more likely to form on warm or hot metal than on cool metal. For example, the first cut in a series
of cuts usually produces the least dross. As the workpiece heats up, more dross can accumulate on
subsequent cuts.
Worn or damaged consumables may produce excess dross.
Straightness of the cut surface
A typical plasma cut surface is slightly concave.
The cut surface may become more concave, or convex. Correct torch height is required to keep the cut
surface acceptably close to straight. Worn consumables also affect the straightness of the cut.
A strongly concave cut surface occurs when the torch-to-work distance is too low. Increase the torch-to-
work distance to straighten the cut surface.
A convex cut surface occurs when the torch-to-work distance is too great or the cutting current is too high.
First, try lowering the torch, then reduce the cutting current.