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Subarc Technology Breakthrough
Variable balance AC squarewave technology can reduce filler metal, flux, labor time, and heat input.
Variable balance AC squarewave submerged arc welding (SAW) technology, from Miller Electric Mfg. Co., overcomes the traditional problems or limitations of SAW with all other processes, including DC electrode positive (DCEP), Dc electrode negative (DCEN) and traditional Ac.
For example, on groove welds on 1.25 in. thick steel plate, variable balance Ac squarewave SAW increases the deposition rate up to 59 percent over DCEP using the same welding parameters and wire types. Thus fabricators can replace old technology and immediately lower weld costs without time lost on developing new welding parameters, although some joints may need requalification.
In applications that benefit from high travel speeds, such as a butt weld on 40 ft. long, 1/4 in. thick plate made with a 1/8 in. diameter electrode, variable balance AC squarewave technology provides travel speeds up to 65 in./min. This is faster than tandem arc sAW (two arcs in series) without any of the problems - initial cost, power use, or consumable consumption of a two-arc system.
Other, proven benefits of a variable balance AC squarewave, as delivered by Miller's Summit Arc 1000 power source, include:
* A guaranteed deposition increase over single wire, DCEP butt welds,
* Smaller included angles and lower filler metal use by up to 42 percent,
* Reduced heat input for minimized warping and base metal dilution,
* Simpler multiple Ac torch configurations by offsetting the cycle of the variable balance Ac squarewave by 60 degrees between torches,
* Substantially lower power consumption and lower hookup costs because the power source uses three-- phase primary power, not single-- phase power.
DC Limitations
Conventional DC SAW forces welding engineers and plant managers to accept a compromise. They can emphasize one of three major variables: high deposition rates, ideal penetration profiles, or lower heat input.
DCEP, which preheats the plate more than the electrode, provides deeper penetration and good wetting at the toes of the weld. However, it has a lower deposition rate and higher heat input. This can be an unfavorable combination for making long welds at higher speeds, for welding plate sensitive to warping, and welding heat treatable materials, such as...