Tweco Max 300 w-TD-750 - Manual (Page 27)

Manual 0-2557 21 OPERATION
4.06 Operating the System
WARNINGS
Disconnect primary power at the source before dis-
assembling the power supply, torch, or torch leads.
Frequently review the Important Safety Precau-
tions at the front of this manual. Be sure the op-
erator is equipped with proper gloves, clothing, eye
and ear protection. Make sure no part of the
operator’s body comes into contact with the work-
piece while the torch is activated.
CAUTION
Sparks from the cutting process can cause damage
to coated, painted, and other surfaces such as glass,
plastic and metal.
NOTE
Handle torch leads with care and protect them from
damage.
A. Piloting
Piloting is harder on parts life than actual cutting be-
cause the pilot arc is directed from the electrode to
the tip rather than to a workpiece. Whenever pos-
sible, avoid excessive pilot arc time to improve parts
life.
B. Torch Standoff
Improper standoff (the distance between the torch tip
and workpiece) can adversely affect tip life as well as
shield cup life. Standoff may also significantly affect
the bevel angle. Reducing standoff will generally re-
sult in a reduced bevel angle.
C. Edge Starting
NOTE
Edge starting is not recommended for machine type
operations as most of the operations use the stand-
off method of starting and finishing on the work
piece.
For edge starts, hold the torch perpendicular to the
workpiece with the front of the tip near(not touch-
ing) the edge of the workpiece at the point where the
cut is to start. When starting at the edge of the plate,
do not pause at the edge and force the arc to "reach"
for the edge of the metal. This effect will cause re-
duced tip life. Establish the cutting arc as quickly as
possible.
D. Direction of Cut
In the Liquid Cooled Model Maximizer 300 Torch, the
plasma gas stream swirls as it leaves the torch to main-
tain a smooth column of gas. This swirl effect results
in one side of a cut being more square than the other.
Viewed along the direction of travel, the right side of
the cut is more square than the left (Refer to Figure 4-
5). To make a square-edged cut along an inside diam-
eter of a circle, the torch should move counterclock-
wise around the circle. To keep the square edge along
an outside diameter cut, the torch should travel in a
clockwise direction.
Right Side
Cut Angle
Left Side
Cut Angle
A-00512
Figure 4-5 Side Characteristics Of Cut
E. Dross
When dross is present on carbon steel, it is commonly
referred to as either “high speed, slow speed, or top
dross”. Dross present on top of the plate is normally
caused by too great a torch to plate distance. "Top
dross" is normally very easy to remove and can often
be wiped off with a welding glove. "Slow speed dross"
is normally present on the bottom edge of the plate.
It can vary from a light to heavy bead, but does not
adhere tightly to the cut edge, and can be easily
scraped off. "High speed dross" usually forms a nar-
row bead along the bottom of the cut edge and is very
difficult to remove. When cutting a troublesome steel,
it is sometimes useful to reduce the cutting speed to
produce "slow speed dross". Any resultant cleanup
can be accomplished by scraping, not grinding.