Miller Electric OM-842 - Manuel (Page 40)

OM-842 Page 36
control unit maintains the programmed initial current
value.
Program execution at this point varies according to
whether pulsing is enabled or disabled. Go to Step 2 if
pulsing is enabled, and Step 3 if pulsing is disabled.
2. When pulsing is enabled:
a. Press and hold Start/Increase to increase the weld
current output. The peak current output increases
at a rate determined by the programmed value of
initial current level, initial slope time, and peak cur-
rent level. The background current output
increases at a rate determined by the programmed
value of initial current level, initial slope time, and
background current level.
b. When Start/Increase is released, the peak and
background current levels that exist are main-
tained.
c. The programmed peak and background current
levels define the maximum limit that the Start/In-
crease push button can command.
d. Press and hold the Decrease push button to de-
crease the weld current output. The peak current
output decreases at a rate determined by the pro-
grammed value of peak current, final slope time,
and final current level. The background current
output decreases at a rate determined by the pro-
grammed value of background current, final slope
time, and final current level.
e. When Decrease is released, the peak and back-
ground current levels that exist when the push
button is released are maintained.
f. Increasing and decreasing the pulsed weld current
output can go on indefinitely.
g. If the weld current output is decreased to the value
programmed for final current, the program enters fi-
nal current and go to postflow.
h. If weld current never exceeds the programmed val-
ue for final current, the weld current must be
manually decreased to zero, at which time the pro-
gram begins postflow.
3. When pulsing is disabled:
a. Press and hold the Start/Increase to increase the
weld current output. The output increases at a rate
determined by the programmed value of initial cur-
rent level, initial slope time, and weld current level.
b. When Start/Increase is released, the weld current
level that exists when the push button is released is
maintained.
c. The programmed weld current defines the maxi-
mum limit the Start/Increase push button can
command.
d. Press and hold the Decrease push button to de-
crease the weld current output. The output
decreases at a rate determined by the pro-
grammed value of weld current, final slope time,
and final current level.
e. When Decrease is released, the weld current level
that exists when the push button is released is
maintained.
f. Increasing and decreasing the weld current output
can go on indefinitely.
g. If the weld current output is decreased to the pro-
grammed final current, the program enters final
current and goes to postflow.
h. If weld current never exceeds the programmed fi-
nal current, the weld current must be manually
decreased to zero, at which time the program be-
gins postflow.
4. After postflow is timed out, the control unit returns to the
Ready condition and waits for the next closure of the
Start/Increase push button. If Start/Increase is pressed
during postflow, the program restarts the weld se-
quence from the beginning without preflow timing.
5. The Stop push button is not functional in this mode.
However, the existence of the arc is monitored by the
control unit. If the arc is manually broken, the program
goes directly to postflow.
F. Operation Procedures For Semi-Automatic 5
Mode
1. When the unit is in the Ready condition (see Section
5-1F), momentarily press Start/Increase to begin pro-
gram execution. The control unit initiates the arc and
executes the programmed sequence to the pro-
grammed weld level. Press Start/Increase to indicate
the end of weld and the beginning of final slope. Once
final slope begins, the Start/Increase push button no
longer has any affect on program execution.
2. After postflow is timed out, the control unit returns to the
Ready condition and waits for the next closure of the
Start/Increase push button. If Start/Increase is pressed
during postflow, the program restarts the weld se-
quence from the beginning without preflow timing.
3. The Stop push button is not functional in this mode.
However, the existence of the arc is monitored by the
control unit. If the arc is manually broken, the program
goes directly to postflow.
6-3. Gas Tungsten Arc Welding (GTAW) In
The Manual Mode
1. Be sure welding power source and related equipment
are installed as instructed in their respective Owner’s
Manuals.
2. Connect a suitable Contactor/Amperage remote con-
trol to the Remote 14 receptacle.
3. Be sure desired weld program (or programs) has been
entered.
4. Place Mode Selector switch in Manual GTAW position.
5. Select and prepare tungsten electrode according to
welding power source Owner’s Manual.
6. Insert electrode into torch.
7. Wear dry insulating gloves and clothing.
8. Connect work clamp to clean, bare metal at workpiece.
9. Turn on shielding gas supply at source.
10. Wear welding helmet with proper filter lens according to
ANSI Z49.1.
11. Energize welding power source.