Tweco XTTM-301 - Manual (Page 50)

Manual 0-4768 4-12 OPERATION
4.07 Operating the System
WARNINGS
Disconnect primary power at the source before disassembling the power supply, torch, or torch leads.
Frequently review the Important Safety Precautions at the front of this manual. Be sure the operator is equipped with
proper gloves, clothing, eye and ear protection. Make sure no part of the operator’s body comes into contact with the
workpiece while the torch is activated.
Sparks from the cutting process can cause damage to coated, painted, and other surfaces such as glass, plastic and metal.
Handle torch leads with care and protect them from damage.
A. Piloting
Piloting is harder on parts life than actual cutting because the pilot arc is directed from the electrode to the tip rather
than to a workpiece. Whenever possible, 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 result 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 standoff 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 touching) 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 reduced tip life. Establish the cutting arc
as quickly as possible.
D. Direction of Cut
In the Liquid Cooled Torch, the plasma gas stream swirls as it leaves the torch to maintain 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. To make a square-edged cut along an inside diameter of a circle,
the torch should move counterclockwise 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
Side Characteristics Of Cut