CUT QUALITY
Note: Cut quality depends heavily on setup and
parameters such as torch standoff, alignment with
the workpiece, cutting speed, gas pressures, and
operator ability.
Cut quality requirements differ depending on
application. For instance, nitride build - up and
bevel angle may be major 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 Fig.6.
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.
KERF WIDTH
The width of the cut (or the width of material
removed during the cut).
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.
CUT SURFACE
The desired or specified condition (smooth or
rough) of the face of the cut.
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.
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.
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.
Fig. 6
18
Top Edge
Rounding
Dross Build-up
Top
Spatter
Cut Surface Drag Lines
Cut Surface
Bevel Angle
Kerf Width
GENERAL CUTTING INFORMATION
WARNING.
Disconnect primary power at
the source before disassembling the
power supply, torch, or torch leads.
Frequently review the Welding Hazards 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 damage to coated,
painted, and other surfaces such as
glass, plastic and metal.
Note: Handle torch leads with care and protect
them from damage.
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
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. 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.
Summary of Contents for PLASMA-40
Page 1: ......
Page 4: ...3 IMPORTANT SAFETY INSTRUCTIONS ...
Page 13: ...12 SYMBOL CHART ...
Page 26: ...25 NOTES ...
Page 27: ...26 NOTES ...
Page 28: ...27 NOTES ...