Tweco 300 Maximizer - Manual (Page 29)

Manual 0-2554 4-7 OPERATION
C. 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 un-
til the arc penetrates the bottom of the plate. As motion
begins, torch standoff should be reduced to the recom-
mended 1/8 - 3/8 inch (3 - 9 mm) distance for optimum
speed and cut quality.
A standard shield cup is recommended for most machine
cutting applications. Do not allow an exposed torch tip
to contact the workpiece.
A method called “running start” is recommended when
piercing with a machine mounted torch. The torch should
be positioned far enough off the cutting line to allow the
pierce to be complete before the cutting line is reached.
This allowance depends on the thickness of the material
and the torch travel speed.
Piercing the plate is not recommended on plates having
a thickness greater than 3/4 in (19 mm). Blowback from
the piercing operation can shorten the life of torch parts.
All piercing should therefore be done as quickly as pos-
sible and at maximum amperage (150 amps) and maxi-
mum standoff.
Pierce off the cutting line and then continue the cut as
needed. 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. This can significantly in-
crease shield cup life.
4.08 Recommended Cutting Speeds
Cutting speed depends on material, thickness, and the
operator’s ability to accurately follow the desired cut line.
The following factors may have an impact on system per-
formance:
• Torch parts wear
• Air quality
• Operator experience
• Torch standoff height
• Proper work cable connection
• Alloy content of material
NOTE
This information represents realistic expectations
using recommended practices and well-maintained
systems. Actual speeds may vary from those shown
in the charts depending on the alloy content of the
selected material.
For complete cutting speed chart data refer to Appendix
2.
4.09 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 dis-
assembling the torch, leads, or power supply.
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. Recommended Gases
Refer to the following table for characteristics of rec-
ommended gases when gouging with Maximizer 300
Torch: