Tweco Max 300 w-Merlin 3000 - Manual (Page 30)

OPERATION 24 Manual 0-2549
A. Recommended Gases
Refer to the following table for characteristics of rec-
ommended gases when gouging with Maximizer 300
Torch:
Characteristics of Recommended Gases for Plasma Arc Gouging
Type of Gas Type of Material
Plasma Secondary Carbon Steel Stainless Steel Aluminum
Air Air Excellent Good Fair
Nitrogen Air Good Good Fair
Nitrogen CO2 Good Good Good
Ar/H2 Nitrogen Good Excellent (Over 3/4 in) Excellent
Ar/H2 Argon Good Excellent Excellent
B. 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 (standoff).
C. Torch Travel Speed
Optimum torch travel speed for gouging is between
20 and 120 inches per minute (0.5 and 3.0 meters per
minute). Travel speed is dependent on current setting,
lead angle, and mode of operation (hand or machine
torch).
D. Current Setting
Current settings depend on torch travel speed, mode
of operation (hand or machine torch), and the amount
of material to be removed.
E. Lead Angle
The angle between the torch and workpiece depends
on the output current setting and torch travel speed.
At 50 amps, the recommended lead angle is 35° (refer
to Figure 4-8). 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-00743
35 o
Workpiece
Torch Head
Standoff Height
1/4 - 3/8"
Figure 4-8 Gouging Angle and Standoff Distance
F. Standoff Distance
The tip to work distance affects gouge quality and
depth. A standoff of 1/4 - 3/8 in (6.3 - 9.5 mm) allows
smooth, consistent metal removal. A smaller standoff
may result in a severance cut rather than a gouge. A
standoff greater than 3/8 in (9.5 mm) may result in
minimal metal removal or loss of transferred main arc.
G. 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