Tweco 82 CutMaster - Manual (Page 39)

CUTMASTER 82
Manual 0-4979 OPERATION 4T-7
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.
Slag Buildup
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.
4T.06 Mechanized Torch Operation
Cutting With Mechanized Torch
The mechanized torch can be 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
Mechanized 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 Slowdown adjustments that
may be required.
Piercing With Machine Torch
To pierce with a machine torch, the arc should be
started with the torch positioned 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 begins, 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.