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Wire Feed Arc Welder
Welding Guidelines (Continued)
The heat setting used depends on the size (diameter) and type of wire, position of the weld, and the thickness of the work piece. Consult specif- ications listed on the welder. It is suggested that the welder practice with scrap metal to adjust settings and compare welds with Figure 12.
WIRE TYPE AND SIZE
The correct choice of wire type involves a variety of factors, such as welding position, work piece material type, thickness and condition of surface to be welded. The American Welding Society, AWS, has set up certain requirements for each type of wire.
FLUX-CORE WIRE
E - 7 0 T - GS
Weld strength, times 10,000 psi
Welding positions (0 for flat or horizontal, 1 for any position)
Tubular flux core wire Flux type
AWS
SOLID WIRE
ER - 70 S - 6
Weld strength, times 1,000 psi
Solid wire
Wire composition
WELD ANGLE
Weld angle is the angle at which the nozzle is held during the welding process. Using the correct angle ensures proper penetration and bead formation. As different welding positions and weld joints become necessary, nozzle angle becomes an increasingly important factor in obtaining a satisfactory weld. Weld angle involves two positions - travel angle and work angle.
Travel angle is the angle in the line of welding and may vary from 5º to 45º
from the vertical, depending on welding conditions.
Work angle is the angle from hori- zontal, measured at right angles to the line of welding. For most applications, a 45º travel angle and 45º work angle is sufficient. For specific applications, consult an arc welding handbook.
5º - 45º
WORK ANGLE
5º - 45º
TRAVEL ANGLE
Figure 11 - Weld Angle
WIRE SPEED
The wire speed is controlled by the knob on the front panel. The speed needs to be “tuned” to the rate at which the wire is being melted in the arc. Tuning is one of the most critical functions in wire feed welding. Tuning should be performed on a scrap piece of metal the same type and thickness as that to be welded. Begin welding with one hand “dragging” the gun nozzle across the scrap piece while adjusting the wire speed with the other hand. Too slow of speed will cause sputtering and the wire will burn up into the contact tip. Too fast a speed will also cause a sputtering sound and the wire will push into the plate before melting. A smooth buzzing sound indicates the wire speed is properly tuned. For aluminum, wire speed is typically set higher (7 - 9 speed range).
NOTE: Repeat the tuning procedure each time there is a change in heat setting, wire diameter or type, or work piece material type or thickness.
TRAVEL SPEED
The travel speed is the rate at which the torch is moved across the weld area. Factors such as diameter and type
of weld wire, amperage, position, and work piece material thickness all affect the speed of travel necessary for completing a good weld (See Fig. 12). When the speed is too fast, the bead is narrow and bead ripples are pointed as shown. When the speed is too slow, the weld metal piles up and the bead is high and wide. For aluminum, travel speed is typically faster.
SLAG REMOVAL (FLUX-CORE WIRE ONLY)
Wear ANSI approved safety
glasses (ANSI Standard Z87.1) and protective clothing when removing slag. Hot, flying debris can cause personal injury to anyone in the area.
After completing the weld, wait for the welded sections to cool. A protective coating called slag now covers the weld bead which prevents contaminants in the air from reacting with the molten metal. Once the weld cools to the point that it is no longer glowing red, the slag can be removed. Removal is done with a chipping hammer. Lightly tap the slag with the hammer and break it loose from the weld bead. The final
NOTE: When making multiple weld passes, remove the slag before each pass.
WELDING POSITIONS
Four basic welding positions can be used; flat, horizontal, vertical, and overhead. Welding in the flat position is easier than any of the others because welding speed can be increased, the molten metal has less tendency to run, better penetration can be achieved, and the work is less fatiguing. Welding is performed with the wire at a 45º travel angle and 45º work angle.
Other positions require different techniques such as a weaving pass, circular pass, and jogging. A higher skill level is required to complete these welds.
Overhead welding is the least desirable position as it is the most difficult and dangerous. Heat setting and wire selection will vary depending upon the position.
All work should be performed in the flat position if possible. For specific applications, consult an arc welding technical manual.
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