Tweco PCM-62 Machine Torch - Manual (Page 27)

Manual 0-2817 4-7 OPERATION
4.10 Gouging
WARNINGS
Be sure the operator is equipped with proper gloves,
clothing, eye and ear protection and that all safety
precautions at the front of this manual have been
followed. Make sure no part of the operator’s body
comes in contact with the workpiece when the torch
is activated.
Disconnect primary power to the system before
disassembling the torch, leads, or power supply.
CAUTIONS
Sparks from plasma gouging can cause damage to
coated, painted or other surfaces such as glass, plas-
tic, and metal.
Check torch parts. The torch parts must correspond
with the type of operation. Refer to Section 4.04,
Torch Parts Selection.
A. Gouging Parameters
Gouging performance depends on parameters such
as torch travel speed, current level, lead angle (the
angle between the torch and workpiece), and the dis-
tance between the torch tip and workpiece (stand-
off).
B. Torch Travel Speed
NOTE
Refer to Appendix Pages for additional informa-
tion as related to the Power Supply used.
Optimum torch travel speed for gouging is depen-
dent on current setting, and lead angle, and mode of
operation (hand or machine torch).
C. Current Setting
Current settings depend on torch travel speed, mode
of operation (hand or machine torch), and the amount
of material to be removed.
D. Lead Angle
The angle between the torch and workpiece depends
on the output current setting and torch travel speed.
At 40 amps, 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.
A-00025
35˚
Workpiece
Torch Head
Standoff Height
1/8 - 1/4"
Direction of Travel
Figure 4-8 Gouging Angle and Standoff Distance
E. 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 distances 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.
F. Slag Build-up
Slag generated by gouging on materials such as car-
bon 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.