Tweco A120 CutMaster - Manual (Page 41)

CUTMASTER A120
Manual 0-4989 OPERATION 4T-7
CAUTION
Sparks from plasma gouging can cause damage
to coated, painted or other surfaces such as glass,
plastic, and metal.
Check torch parts. The torch parts must correspond
with the type of operation. Refer to Section 4T.09,
Torch Parts Selection.
Gouging Parameters
Gouging performance depends on parameters such as
torch travel speed, current level, lead angle (the angle be-
tween the torch and workpiece), and the distance between
the torch tip and workpiece (standoff).
CAUTION
Touching the torch tip or shield cup to the work
surface will cause excessive parts wear.
Torch Travel Speed
NOTE
Refer to Appendix Pages for additional information
as related to the Power Supply used.
Optimum torch travel speed is dependent on current set-
ting, lead angle, and mode of operation (hand or machine
torch).
Current Setting
Current settings depend on torch travel speed, mode of
operation (hand or machine torch), and the amount of
material to be removed.
Lead Angle
The angle between the torch and workpiece depends on
the output current setting and torch travel speed. The
recommended lead angle is 35°. At a lead angle greater
than 45° the molten metal will not be blown out of the
gouge and may be blown back onto the torch. If the lead
angle is too small (less than 35°), less material may be
removed, requiring more passes. In some applications,
such as removing welds or working with light metal, this
may be desirable.
35°
Workpiece
Torch Head
Standoff Height
A-00941_AB
Gouging Angle and Standoff Distance
Standoff Distance
The tip to work distance affects gouge quality and depth.
Standoff distance of 1/8 - 1/4 inch (3 - 6 mm) allows for
smooth, consistent metal removal. Smaller standoff dis-
tances may result in a severance cut rather than a gouge.
Standoff distances greater than 1/4 inch (6 mm) may result
in minimal metal removal or loss of transferred main arc.
Slag Buildup
Slag generated by gouging on materials such as carbon and
stainless steels, nickels, and alloyed steels, can be removed
easily in most cases. Slag does not obstruct the gouging
process if it accumulates to the side of the gouge path.
However, slag build - up can cause inconsistencies and
irregular metal removal if large amounts of material build
up in front of the arc. The build - up is most often a result
of improper travel speed, lead angle, or standoff height.