Tweco 150XL CE PAK Master - Manuel (Page 33)

Manual 0-2826 4-5 OPERATION
G. Work Cable Connection
Check for a solid and clean work cable connection to
the workpiece. The area must be free from paint and
rust.
H. Torch Connection
Check that torch is properly connected.
I. Plasma Gas Purge (Pre-Flow)
Move the ON/OFF switch to ON position. To start
the pre-flow move the RUN/SET switch to SET posi-
tion for a minimum of 20 seconds. The gas purge will
remove any moisture that may have accumulated in
the torch and leads while the system was shut down.
The torch cannot be activated during gas purge pro-
cess.
J. Current Output Level Selection
Select the desired current output level, 30-120 amps,
for the operation.
K. Set Operating Pressure
Move the RUN/SET switch to SET position. Set
plasma and secondary pressures. Adjust the gas pres-
sure to 65 psi (4.5 bar) for plasma and 60 psi (4.1 bar)
for secondary.
L. Ready for Operation
Return the RUN/SET switch to RUN position. The
system is now ready for operation.
NOTE
Refer to Appendix 2 for a detailed block diagram of
the Sequence of Operation.
4.05 Cut Quality
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
Figure 4-5:
Cut Surface
The condition (smooth or rough) of the face of the cut.
Bevel Angle
The angle between the surface of the cut edge and a
plane perpendicular to the surface of the plate. A per-
fectly 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 work-
piece.
Dross Build-up and Top Spatter
Dross is molten material which is not blown out of
the cut area and re-solidifies on the plate. Top spatter
is dross which accumulates on the top surface of the
workpiece. Excessive dross may require secondary
clean-up operations after cutting.
Kerf Width
The width of material removed during the cut.
Nitride Build-up
Nitride deposits which may remain on the surface of
the cut when nitrogen is present in the plasma gas
stream. Nitride buildups may create difficulties if the
material is welded after the cutting process.