Tweco A120 CutMaster - Manual (Page 35)

CUTMASTER A120
Manual 0-4989 OPERATION 4T-1
SECTION 4 TORCH:
OPERATION
4T.01 Machine and Automated Torch Operation
Cutting With Machine or Automated Torch
These torches are activated by remote control pendant or
by a remote interface device such as CNC.
1. To start a cut at the plate edge, position the center of
the torch along the edge of the plate.
Travel Speed
Proper travel speed is indicated by the trail of the arc which
is seen below the plate. The arc can be one of the following:
1. Straight Arc
A straight arc is perpendicular to the workpiece
surface. This arc is generally recommended
for the best cut using air plasma on stainless or
aluminum.
2. Leading Arc
The leading arc is directed in the same direction
as torch travel. A five degree leading arc is gener-
ally recommended for air plasma on mild steel.
3. Trailing Arc
The trailing arc is directed in the opposite direc-
tion as torch travel.
Standoff Distance
Straight Arc
Trailing Arc
Leading Arc
Direction of Torch Travel
A-02586
Automation and Machine Torch Operation
For optimum smooth surface quality, the travel speed
should be adjusted so that only the leading edge of the arc
column produces the cut. If the travel speed is too slow,
a rough cut will be produced as the arc moves from side
to side in search of metal for transfer.
Travel speed also affects the bevel angle of a cut. When
cutting in a circle or around a corner, slowing down the
travel speed will result in a squarer cut. The power source
output should be reduced also. Refer to the appropriate
Control Module Operating Manual for any Corner Slow-
down adjustments that may be required.
Piercing With Machine or Automated Torch
To pierce, the arc should be started with the torch posi-
tioned as high as possible above the plate while allowing the
arc to transfer and pierce. This standoff helps avoid having
molten metal blow back onto the front end of the torch.
When operating with a cutting machine, a pierce or dwell
time is required. Torch travel should not be enabled until
the arc penetrates the bottom of the plate. As motion be-
gins, torch standoff should be reduced to the recommended
1/8 - 1/4 inch (3-6 mm) distance for optimum speed and
cut quality. Clean spatter and scale from the shield cup
and the tip as soon as possible. Spraying or dipping the
shield cup in anti - spatter compound will minimize the
amount of scale which adheres to it.
4T.02 Automation Torch Parts Selection
Check the torch for proper consumable parts. The parts
supplied in the torch may not be correct for the operator’s
chosen amperage level. The torch parts must correspond
with the type of operation.
Torch parts:
Shield Cup, Cutting Tip, Electrode and Starter Cartridge
NOTE
Refer to Sections 4T.08 and following for additional
information on torch parts.
Change the torch parts for a different operation as follows:
WARNING
Disconnect primary power at the source before
assembling or disassembling torch parts, or torch
and leads assemblies.