Presetting Wire Feed Speed; Setting Constant Wire Feed Speed (Cv Mode; Setting Arc Sensing Wire Feed Speed (Vv [Cc] Mode - Lincoln Electric LN-25 Service Manual

B-7
screw in the gearbox conductor block and pull the
gun cable forward about six inches.
be a slight waviness in the exposed wire. If there
is no waviness, the pressure is too low
the pressure setting Ú
1
4
place and repeat the above steps.

PRESETTING WIRE FEED SPEED

The LN-25 permits accurate presetting of the desired
wire feed speed, before welding, in both CV and CC
wire feed modes.
SETTING CONSTANT WIRE FEED SPEED (CV
MODE)
a. Set Wire Feed Mode switch to CV position.
b. Set Dial Range switch to LO position for wire feed
speeds up to 350 in/min., or HI position for wire
feed speeds over 350 in/min.
c. Set Wire Feed dial to the desired wire feed speed
on the selected calibrated dial range.
The wire speed will remain constant at the value set,
independent of arc voltage changes, as long as the
arc voltage does not drop below the value per the
chart below for the max. wire feed speed shown:
Maximum Speed
350 IPM
400 IPM
500 IPM
600 IPM
700 IPM
SETTING ARC SENSING WIRE FEED SPEED
(CC MODE)
When using a constant current (formerly variable
voltage) power source, welding performance is im
proved using arc sensing wire feed speed (CC [VV]
mode). In this wire feed mode the wire speed
increases if arc voltage increases, and decreases if
arc voltage decreases, but remains constant at any
specific voltage level.
The LN-25 permits accurate CC mode presetting of
the desired wire feed speed, for the desired arc
voltage to be used, by setting the Wire Speed dial in
the following manner before welding:
a. Set Wire Feed Mode switch to CC position.
OPERATION
There should
. Increase
turn, lock the gun cable in
Minimum Arc V olts
15V
17V
21V
24V
27V
FIGURE B.3 Ð CC WIRE SPEED SETTING.
DESIRED IN/MIN
700
650
600
550
500
450
400
350
300
250
200
150
100
50
50 100 150 200 250 300 350 400 450 500 550 600 650 700
CC Wire Speed Setting
(Hl or LO Range)
b. Referring to the graph located above the Mode
switch (also shown in Figure B.3):
1. Select the horizontal line representing the DE-
SIRED IN/MIN. for the welding procedure. (See
example arrow line for 375 in/min.)
2. Select the diagonal line representing the
VOLTS to be used for the welding procedure.
(See example arrow line for 29 volts.)
3. Determine the vertical line representing the CC
WIRE SPEED SETTING where the above two
lines cross. (See example arrow line for 450.)
c. Set the Wire Speed dial to the value determined
in Step (3) above (450 for example used). Use HI
Dial Range if value to be set is over 350.
-
The wire will feed at the DESIRED IN/MIN speed
when the welding power source is set to the arc
voltage to be used for the weld procedure (375 in/min.
at 29V for example used).
A chart representation of the CC wire speed setting
graph is shown in Figure B.4, giving the Wire Speed
dial setting required for the DESIRED IN/MIN and
VOLTS used for the welding procedures:
LN-25
B-7
ARC VOLTS USED
31
29
27
25
23
21
19
17
15
ARC
ARC
35