Tweco 1000 Merlin(Sept1999) - Manual (Page 34)

OPERATION 30 Manual 0-2731
d. Turn the knob clockwise to increase or counter-
clockwise to decrease gas pressure.
e. Push the knob back in to lock the pressure setting.
f. Slowly close the valve on the top of the Plasma Gas
flowmeter until the desired flow rate is achieved.
3. To set the Secondary Gas pressure do the following:
a. Set the Secondary Mode Selector switch to Sec Pres-
sure position.
b. Pull out the knob on the Secondary Gas regulator.
c. Turn the knob clockwise to increase or counterclock-
wise to decrease gas pressure.
d. Push the knob back in to lock the pressure setting.
4. To set the Lo-Flow Gas flow rate do the following:
a. Set the Secondary Mode selector switch to Lo-Flow
Gas position.
b. Fully open the valve on the top of the Lo-Flow Gas
flowmeter.
c. Pull out the knob on the Secondary Gas regulator.
d. Turn the knob clockwise to increase or counter-
clockwise to decrease gas pressure.
e. Push the knob back in to lock the pressure setting.
f. Slowly close the valve on the top of the Lo-Flow
flowmeter until the desired flow rate is achieved.
5. To set the Water (H
2
O) Mist flow rate do the following:
a. Set the Secondary Mode selector switch to H
2
O Mist
position.
b. Slowly open the valve on the top of the H
2
O Mist
flowmeter until the desired flow rate is achieved.
6. Place the RUN/SET switch to the RUN position.
NOTE
For recommended gas pressures and flows for vari-
ous cutting operations refer to the Instruction
Manual, 0-2710, supplied with the Maximizer 300
Torch.
L. Ready for Operation
Return the RUN/SET switch to RUN position. The
system is now ready for operation.
NOTE
Refer to Appendix II for a detailed block diagram
of the Sequence of Operation.
4.06 Cut Quality
Cut quality requirements differ depending on applica-
tion. 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 opera-
tion.
The following cut quality characteristics are illustrated
in Figure 4-7:
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 cut edge
of the carbon steel when nitrogen is present in the
plasma gas stream. Nitride buildups may create dif-
ficulties if the steel is welded after the cutting pro-
cess.