Hypertherm Powermax45 Service Manual - Manual (Page 74)

operation
4-14
powermax
45 Service Manual
High-speed dross forms when the cutting speed is too fast and the arc lags behind. It forms as a thin, linear bead of
solid metal attached very close to the cut. It is welded to the bottom of the cut and is difficult to remove. To reduce
high-speed dross:
• Decrease the cutting speed.
• Decrease arc voltage to decrease the torch-to-work distance.
Notes: 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 will likely produce the least dross. As the workpiece heats up, more
dross may form on subsequent cuts.
Dross is more likely to form on mild steel than on stainless steel or aluminum.
Worn or damaged consumables may produce intermittent 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.
To pierce a workpiece using the machine torch
As with the hand torch, you can start a cut with the machine torch at the edge of the workpiece or by piercing the
workpiece. Piercing will result in a shorter consumable life than with edge starts.
The cut charts include a column for the height at which the torch should be when starting a pierce. For the Powermax45,
the pierce height is generally 2.5 times the torch cutting height. Refer to the cut charts for specifics.
The pierce delay must be sufficiently long that the arc can pierce the material before the torch moves, but not so long
that the arc “wanders” while trying to find the edge of a large hole.
When piercing maximum thicknesses, the ring of dross that forms during the pierce may become high enough to contact
the torch when the torch begins to move after the pierce is complete.