Application Stories

Construction Firms Gain Productivity through Extended Stick-Out Welding Procedures
 
New consumables increase welding output, with surprising results

Conventional wisdom has always prescribed that extending wire electrical stick-out beyond the recommended 3/4 in. invites a host of problems, such as excessive spatter, burn through, and porosity. The arc will wander as heat rises and puddles will grow out of control.

UltraCore®, the new family of flux-cored wire from The Lincoln Electric Company has turned those notions around, allowing an extended stick-out setting to actually offer a variety of advantages to the flux-cored welding process. By increasing electrical stick-out, operators are given the ability to increase deposition rates by pre-melting the wire before it hits the weld puddle. Some companies are starting to see substantial productivity gains merely by changing their wire and adjusting their torches.

Complete Engineering and Construction Inc. (CEC) was the first to put the concept to task on a major project. The Louisiana based company won a contract to build a new barge bridge across the Belle River on State Route 70, deep in Cajun country.

The existing bridge was 50 years old and showed its age in wear. It was a unique floating design that swung open laterally from one end, like a door, to make way for river traffic. Local nostalgia dictated that the new bridge would do the same. The Department of Transportation agreed, but insisted on a more robust design that would withstand increased traffic and today’s heavier trucks.

Using the same concept, a bridge twice the original size was designed – from 150 tons to 300 tons. For the initial fabrication phase, CEC devised a semi-automatic welding process that employed a Bug-O positioning system of drives, carriages and rails on which the work traveled on a conveyer under fixed welding guns.

The system allowed CEC to quickly weld the heavy, rectangular pontoons that would keep the bridge afloat. The company purchased six Lincoln Electric’s Invertec® V-350 PRO welders, accompanied by Lincoln’s LN™-25 PRO wire feeders for semi-automatic welds and Lincoln’s LN™-74 heavy duty wire feeders for the Bug-O system.

The Bug-O system worked the larger sections constructed of 3/4 in. steel, welded with Lincoln’s 1/16 in. UltraCore® E71T-1/ T-9 flux-cored wire and 100% CO2 shielding gas.

In doing so, it was likely the only major operation in the country running 1/16 in. wire from a 350-amp machine. It was a procedure practically unheard of, especially for a tightly regulated government project.

How it works

Welding wire of this thickness through a machine with a relatively small output became possible when Lincoln Electric’s sales representative, Tom O’Brien, suggested using an extended stickout method. After changing to new nozzles, the UltraCore® wire extended a total of 1 1/4 in. past the contact tip before hitting the work surface.

This simple adjustment accomplished several objectives. First, it allowed the wire to preheat as it fed from the contact tip to the weld puddle. This provided better penetration and deposition on heavy gauge steel – much more so than a 350-amp machine would be expected to handle with 1/16 in. wire.

The longer stick-out creates higher melt-off rates, faster travel speeds or greater deposition. Normally, this could only be the result of higher amps, but CEC’s machines were already pushed to their limits. And with 1/16 in. wire, the same work would have required a 400- to 600-amp welding output on 3/4 in. steel.

Next, because the arc started unusually far from the tip, there was greater opportunity for spatter to clog the nozzle and contact tip. Lincoln Electric’s UltraCore® wire has a chemical composition that greatly reduces spatter. So CEC’s clean-up time was reduced by more than 90% with the extended stick-out, according to project manager, Richard Bickle.

“Typically, we would have to clean the nozzle every five to six minutes,” he said. “But with the wire stick-out method, we maybe cleaned it a few times a day. We estimated that there was about 70% less slag and debris. It was unbelievable.”

Bickel said the weld quality and appearance were both very high, noting that all welds were ultrasonically tested.

Traditionally, recommended wire stick-outs range from 1/2 in. to 3/4 in. depending on amperage, metal thickness and other factors. To accommodate for lower amperage machines, CEC ran its wire at more than an inch from the contract tip. It was an adjustment made possible only with the UltraCore® wire.

Lincoln Electric’s engineers made the breakthrough discovery while testing their consumable products in a multitude of scenarios. UltraCore® wire is stiffer that other wires, while still able to run smoothly through a feeder. Its stiffness and other chemical qualities prevent the arc from wandering when the wire is extended beyond normal limits.

Its unique properties decrease spatter, from which CEC realized an overall 20% productivity gain by dramatically reducing tip and nozzle cleaning. Because the wire ran smoothly on 100% CO2, Argon and its associated costs also were avoided. The ability to run 1/16 in. wire with 350-amp machines was an additional cost savings. Normally, they would have run higher priced .052 in. or .045 in. wire less deposition.

Putting the idea to work

Initially, Bickle struggled with finding qualified welders. It posed yet more concerns when CEC set out to incorporate a new welding method. But no additional skill was needed, Bickle eventually learned. The arc performance made the job more user friendly, and the stick-out position created no additional obstacles, he said.

Other companies are finding success with extended stick-out positions as well. Owen Steel of Columbia, S.C., builds a wide variety of complex structures, including Manhattan skyscrapers and major league sports arenas.

“UltraCore®’s long stick-out procedures have allowed us to maximize the deposition rate, while giving our welders better arc control,” said Owen Steel welding supervisor, Dexter James.

Owen Steel uses 1/16 in. 71C wire with an extended stick-out of up to 1 3/4 in. That is combined with high wire speeds, higher deposition rates and arc stability, while maintaining arc performance and weld properties. Overall, Owen is reporting a 30% productivity gain with the new technique.

Bickle contends that despite the obvious cost advantages, the welds are better and easier to make.

“When you weld with this wire, it doesn’t make that traditional crackling noise of flux-cored that everyone is used to,” he said. “It’s a very sweet process. It just hums, and quite frankly anyone could make a good weld with this stuff.”

Bickle said relatively new welders used the stick-out method in all positions, including vertical up and overhead, with no issues.

“This really turned out well,” he said. “When I began researching new equipment and consumables for this project, my main concern was finding a company that offered the best technical support. When I asked the Lincoln Electric’s rep for the best new technology, I never thought he’d come back with something like this.”