Tweco 250i Multi Process Welding Inverter 2RT Wire Feeder - Manual (Page 58)

TRANSMIG 250I BASIC WELDING
BASIC WELDING 4-2 Manual 0-5187
Butt & Horizontal Welds
Art # A-08993
Figure 4-4
Horizontal Fillet Weld
Art # A-08994
Figure 4-5
Vertical Fillet Welds Art # A-08995
Figure 4-6
Overhead Weld
Art # A-08996
Figure 4-7
Distance from the MIG Torch Nozzle to the Work Piece
The electrode wire stick out from the MIG Torch nozzle
should be between 10mm to 20mm. This distance may
vary depending on the type of joint that is being welded.
Travel Speed
The speed at which the molten pool travels influences
the width of the weld and penetration of the welding run.
MIG Welding (GMAW) Variables
Most of the welding done by all processes is on carbon
steel. The items below describe the welding variables in
short-arc welding of 0.6mm to 6.4mm) mild sheet or
plate. The applied techniques and end results in the GMAW
process are controlled by these variables.
Preselected Variables
Preselected variables depend upon the type of material
being welded, the thickness of the material, the welding
position, the deposition rate and the mechanical proper-
ties. These variables are:
• Type of electrode wire
• Size of electrode wire
• Type of gas ((not applicable for FCAW self shielding
wires)
• Gas flow rate (not applicable for FCAW self shielding
wires)
Primary Adjustable Variables
These control the process after preselected variables have
been found. They control the penetration, bead width, bead
height, arc stability, deposition rate and weld soundness.
They are:
• Arc Voltage
• Welding current (wire feed speed)
• Travel speed
Secondary Adjustable Variables
These variables cause changes in primary adjustable
variables which in turn cause the desired change in the
bead formation. They are:
1. Stick-out (distance between the end of the con-
tact tube (tip) and the end of the electrode wire).
Maintain at about 10mm stick-out
2. Wire Feed Speed. Increase in wire feed speed
increases weld current, Decrease in wire feed
speed decreases weld current.