Tweco Maximizer 300 Torch for BNFL - Manual (Page 29)

Manual 0-2990 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 until the arc penetrates the bottom of the
plate. As motion begins, torch standoff should be
reduced to the recommended 1/8 - 3/8 inch (3 - 10
mm) distance for optimum speed and cut quality.
A standard shield cup is recommended for most ma-
chine cutting applications. Do not allow an exposed
torch tip to contact the workpiece.
Piercing the plate is not recommended on plates hav-
ing a thickness greater than 1 inch (25.4 mm). Blow-
back from the piercing operation can shorten the life
of torch parts. All piercing should therefore be done
as quickly as possible and at maximum amperage and
maximum 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 dip-
ping the shield cup in anti-spatter compound will
minimize the amount of scale which adheres to it.
This can significantly increase 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 in Section 1 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:
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 (stand-
off).
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 set-
ting, 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.