Connecting The Ground Clamp To The Workpiece; Powering Up The Unit; Principles Of Plasma Cutting; Learning To Plasma Cut - Craftsman 196.205070 Owner's Manual

4. Turn on the air supply. Make sure that
the air supply pressure is at least 90psi.
(90 -120 psi is ideal)
5. Pull out the air pressure regulator knob
and set a pressure of 65 psi by turning
the knob clockwise.
6. When the pressure on the air regulator
gauge is set to 65 psi, lock the knob in
position by firmly pushing down on it.
(See Figure 6)
0
Figure 6
Adjusting Regulator
Pressure
CONNECTING THE GROUND CLAMP
TO THE WORKPIECE
1. Remove any dirt, grease, scale, rust,
paint, etc. from the area of the workpiece
where the ground clamp is to be connect-
ed.
2. The ground clamp should be connected
to the workpiece as close to the area
being cut as possible. Make sure when
connecting the ground clamp that neither
the ground clamp or the ground cable wilt
intersect the intended cut line.
3. Fasten the ground clamp to the work-
piece. Make certain the ground clamp is
securely fastened to the workpiece so
that it will not be likely to come loose dur-
ing the plasma cutting operation.
POWERING UP THE UNIT
1. Plug power cord into properly grounded
220VAC, 60Hz, single phase power
source.
2. Switch the unit ON, using the main power
switch on the rear panel of the plasma
cutter. A hissing of air wilt be apparent for
a short period as the system is charged
and the air filter drain valve closes.
Make sure that the Power Indicator Lamp
on the front panel of the machine is on,
3,
12
indicating that the plasma cutter is sup-
plied with power.
4. Holding the torch away from yourself and
others in the work area, pull the torch
trigger and verify that the pressure indi-
cated on the pressure gauge is at
approximately 65 psi.
Note: This Plasma Cutter has an internal
safety feature which prevents accidental
arcs. To light the pilot arc, press the torch
button; release it and press it again within 3
seconds The pilot arc will go out after
approximately 2-3 seconds if cutting has not
begun. To relight the pilot arc, simply repeat
the steps above. Avoid unnecessary lighting
of the pilot arc to prevent consumption of the
electrode and nozzle.
PRINCIPLES OF PLASMA CUTTING
Plasma cutting is a fast, clean and distor-
tion free means of cutting through all types of
metal from mild and stainless steels to alu-
minum, brass and copper.
The process relies upon the chemical
reaction of air when subjected to very high
temperatures. The air is ionized, leaving the
atoms positively charged. In the ionized
state, the air is electrically conductive and
called "plasma."
A standing electric arc is created to
achieve the very high temperature required
to create plasma. By forcing the plasma
through a small nozzle, the arc is constricted
and its temperature is increased to over
36,000 degrees fahrenheit and concentrated
into a very small area.
When the plasma is directed at a conduc-
tive material (which is connected to the
ground clamp of the plasma cutter) the arc is
transferred through the plasma to the materi-
al. The high energy of the arc melts the
material. The melted metal material is simul-
taneously forced out of the cut area by the
air flow. As this glowing metal is removed
from the path of the plasma arc, the result is
a fast, clean cut.
The standing arc has to be created by
producing an ionized path in the air. This is
achieved by applying a very high voltage, at
high frequency, between the electrode and
the tip/work, causing a high frequency spark.
The main arc will ignite as soon as the tip
and nozzle are ionized.
Whether you have used a plasma cutter