Hypertherm Powermax105 Service Manual - Manual (Page 136)

Mechanized cutting
7-10
powermax
105 Service Manual
Piercing 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 may result in a shorter consumable life than with edge starts.
The cut charts include a column for the recommended torch height when starting a pierce. For the Powermax105, the
pierce height is generally 2.5 times the cutting height. Refer to the cut charts for specifics.
The pierce delay must be long enough 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. As consumables wear, this delay time may need
to be increased. Pierce delay times given in the cut charts are based on average delay times throughout the life of the
consumables.
When piercing materials close to the maximum thickness for a specific process, consider the following important
factors:
• Allow a lead-in distance approximately equal to the thickness of the material being pierced. For example, 20 mm
(3/4 in) material requires a 20 mm lead-in.
• To avoid damage to the shield from the buildup of molten material created by the pierce, do not allow the torch
to descend to cut height until it has cleared the puddle of molten material.
• Different material chemistries can have an adverse effect on the pierce capability of the system. In particular,
high-strength steel with a high manganese or silicon content can reduce the maximum pierce capability.
Hypertherm derives mild steel parameters using certified A-36 plate.