Wire Feed Arc Welder
Welding Guidelines (Continued)
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. The AWS classification for
FLUX-CORED WIRE
E - 7 0 T - GS
Weld strength, times 10,000 pounds per square inch Welding positions (0 for flat or horizontal, 1 for any position) Tubular flux core wire Flux type
AWS
WELD ANGLE
Weld angle is the angle at which the nozzle is held during the welding process. Weld angle involves two positions - travel angle and work angle.
5º - 45º
WORK ANGLE
5º - 45º
TRAVEL ANGLE
Figure 8 - Weld 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 horizontal, 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.
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. 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.
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 effect 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.
SLAG REMOVAL (FLUX-CORED 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
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.
All work should be performed in the flat position if possible. For specific applications, consult an arc welding technical manual.
WELD PASSES
Sometimes more then one pass is necessary to fill the joint. The root pass is first, followed by filler passes and the cover pass. (See Figures 9 and 10.) If the pieces are thick, it may be necessary to bevel the edges that are joined at a 60º angle. Remember to remove the slag before each pass.
Cover
Filler
Root
Figure 9 - Weld Passes
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