Tweco CutMaster 12mm - Manual (Page 34)

CUTMASTER 12mm
4T-2 OPERATION Manual 0-5076
Cut Surface
The desired or specified condition (smooth or rough) of
the face of the cut.
Nitride Build - Up
Nitride deposits can be left on the surface of the cut when
nitrogen is present in the plasma gas stream. These build-
ups may create difficulties if the material is to be welded
after the cutting process.
Bevel Angle
The angle between the surface of the cut edge and a plane
perpendicular to the surface of the plate. A perfectly per-
pendicular cut would result in a 0° bevel angle.
Top - Edge Rounding
Rounding on the top edge of a cut due to wearing from the
initial contact of the plasma arc on the workpiece.
Bottom Dross Buildup
Molten material which is not blown out of the cut area
and resolidifies on the plate. Excessive dross may require
secondary cleanup operations after cutting.
Kerf Width
The width of the cut (or the width of material removed
during the cut).
Top Spatter (Dross)
Top spatter or dross on the top of the cut caused by slow
travel speed, excess cutting height, or cutting tip whose
orifice has become elongated.
4T.03 General Cutting Information
!
WARNING
Disconnect primary power at the source before dis-
assembling 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.
CAUTION
Sparks from the cutting process can cause dam-
age to coated, painted, and other surfaces such as
glass, plastic and metal.
NOTE
Handle torch leads with care and protect them
from damage.
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.
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 more square cut.
Edge Starting
For edge starts, hold the torch perpendicular to the work-
piece 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.
Establish the cutting arc as quickly as possible.
Direction of Cut
In the torches, 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.
Right Side
Cut Angle
Left Side
Cut Angle
A-00512
Side Characteristics Of Cut
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.
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,