The deposition rate describes how much usable weld metal will be deposited in one hour of actual arc-on time. Because the mig process is very efficient, only a very small amount of weld metal is lost as spatter. The deposition rate for any wire is calculated by the equation:
Torch Manipulations No discussion of welding techniques would be complete without some reference to the methods of torch manipulation. The recommendations which follow are only to serve as a guide to be used during welder training. As the individual welders become more proficient with the Mig process, they will adapt their torch manipulations to best suit the job at hand. FLAT POSITION Recommended weaving patterns, torch positions and bead sequence are shown in Figure 7-15. For the single-pass, butted joint, a slight back-stepping motion is used. Gapped root passes are made with a small, back-and-forth weave pattern. For fill and cover passes, the same weave, with an adjustment for the desired width, is used, with care taken to pause at the sidewalls to obtain adquate fill in these areas.
Figure 7-15 - Torch Manipulations
HORIZONTAL POSITION Recommended weaving patterns, torch positions and bead sequences are shown in Figure 7-16. For fillet welds, a circular motion is recommended. For butt weld root passes and fill passes, an in-line, back-and- forth motion is used with width adjustments as required. A slight pause is used at the tie-in to the previous bead.
Figure 7-16 - Torch Manipulations
VERTICAL POSITION Recommended weaving patterns and torch positions for vertical up and vertical down are shown in Figure 7- 17. With vertical up, for a square edge preparation an in-line, back-and-forth weave is used. For a bevelled, multipass joint a ”U” pattern is used for the root. The fill and cover passes are made using a side-to-side weave with a backstep at the walls. The length of the backstep is on the order of a wire diameter. For a vertical up fillet a ”Christmas Tree” pattern is used with pauses at the side walls. For vertical down an inverted ”U” pattern is used, pausing at the side walls for the root, fill, and cover passes. Always take care in vertical down welding to keep the arc on the leading edge of the puddle. Preventing the molten metal from running ahead of the arc will improve weld soundness.
Figure 7-17 -Torch Manipulations
OVERHEAD POSITION Recommended weaving patterns and torch positions for the overhead position are shown in Figure 7-18. Again, a back-and- forth weave is used with pauses at the plate sidewalls. This applies to root, fill, and cover passes.
Figure 7-18 Recommended weaving patterns and torch positions for the overhead position
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