Lincoln Electric IM677 RED-D-ARC LN-25 - Manual (Page 17)

LN-25
B-6 B-6
OPERATION
3. If the only result is drive roll slippage, shut off
the power source, then loosen the gun cable
clamping screw in the gearbox conductor block
and pull the gun cable forward about six inches.
There should be a slight waviness in the
exposed wire. If there is no waviness, the
pressure is too low. Increase the pressure
setting
1 ⁄
4
turn, lock the gun cable in 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.
S E T T I N G C O N S T A N T W I R E F E E D S P E E D
(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 Minimum Arc Volts
350 IPM 15V
400 IPM 17V
500 IPM 21V
600 IPM 24V
700 IPM 27V
SETTING ARC SENSING WIRE FEED SPEED
(VV [CC] MODE)
When using a constant current (formerly variable
voltage) power source, welding performance is im-
proved using arc sensing wire feed speed (VV [CC]
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 VV (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 VV (CC) position.
FIGURE B.3 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 ARC
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 VV (CC) wire speed
setting graph is shown in Figure B.4, giving the Wire
Speed dial setting required for the DESIRED IN/MIN
and ARC VOLTS used for the welding procedures: