Tweco 42 CutMaster Service Manual - Manual (Page 33)

OPERATION CUTMASTER 42
Manual 0-5171 4-7 Operation
4.04 Cut Quality
NOTE
Cut quality depends heavily on setup and
parameters such as torch standoff, alignment
with the workpiece, cutting speed, gas pres-
sures, and operator ability.
Refer to appendix pages for additional infor-
mation as related to the power supply used.
Cut quality requirements differ depending on application.
For instance, nitride build-up and bevel angle may be ma-
jor factors when the surface will be welded after cutting.
Dross-free cutting is important when finish cut quality
is desired to avoid a secondary cleaning operation. The
following cut quality characteristics are illustrated in the
following figure:
Kerf Width
Cut Surface
Bevel Angle
Top Edge
Rounding
Cut Surface
Drag Lines
Dross
Build-Up
Top
Spatter
A-00007
Cut Quality Characteristics
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 buildups 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 perpendicular 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.