Appendix B

STT WAVE SHAPING PRINCIPLES

B-13

B.5.2 BACKGROUND CURRENT

The Background current controls the overall heat input to the weld. Adjusting this level too high will form a large droplet resulting in globular type transfer and increased spatter. Adjusting this level too low will cause wire stubbing and poor wetting of the weld metal.

ADJUST BEAD SHAPE USING BACKGROUND CURRENT

LOW OPTIMUM HIGH

24850065

NOTE: Applications using 100% CO2 require less background current than similar procedures using high Argon blends. This is due to greater heat generated in the 100% CO2 arc.

CONTACT TIP TO WORK DISTANCE

LONG OPTIMUM SHORT

27850065

B.5.3 TAILOUT

The tailout provides additional heat without the molten droplet becoming too large. Increase tailout as needed to add heat to the arc without increasing arc length. (This will allow for faster travel speeds and improved wetting). As tailout is increased, the peal and/or background current is usually reduced.

WAVE DESIGNER

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Image 67
Lincoln Electric IM649 manual Background Current, Tailout