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Small fabricator improving armored personnel carriers: added weldments are increasing the protection the military's armored personnel carrier (APC) provides for troops in Iraq.

A major defense contractor devised a system of hardened steel fins that are mounted to the sides of the APCs at a downward 45[degrees] angle. The fins deflect rocket-propelled grenades (RPGs) away from the skin of the vehicle, where they explode without harming the soldiers inside.


To fabricate and weld the fins to mounting brackets that are bolted to the sides of the APCs, the defense contractor turned to two strategically partnered Wisconsin companies: Performance Welding, a woman-owned small business located in tiny Freedom, that specializes in certified welding services, and Val Fab Inc., a veteran service-disabled owned company in Neenah, specializing in custom metal fabrication. Their combined reputations for providing quality custom metal fabricated products, certified welding services and on-time delivery have allowed them to become preferred suppliers to numerous large manufacturers and defense contractors.

"Those fins are saving a lot of our men and women in Iraq from injuries or worse," says Kurt Wollenberg, vice president of Performance Welding. "I have some terrific fabricators working for me and their welding expertise, and the reliability of our equipment, is why we continue to Performance Welding's fabricators rely on the XMT[R] Series of multiprocess inverters from Miller Electric Mfg. Co. (Appleton, WI). Currently they use three XMT 304 CC/CV machines and one new XMT 350 CC/CV inverter featuring Auto-Line[TM] primary power management technology (see sidebar). With a rated output of 350 amps/34 volts at 60% duty cycle, three-phase, and 300 amps/32 volts at 60% duty cycle, single-phase, the XMT 350 offers 24% more power than the XMT 304.

Wollenberg says, "The XMT 350 has shown the ability to ride through voltage drops, which can shut down the 304s, and maintain a steady arc. That was critical during the APC fin project. We had to fabricate 188 sets of fins, a left and a right unit, in a three-week window."

The fin project is just the latest job Performance Welding has tackled for the Defense Department, through its partnership with Val Fab.

"Both of our companies qualify as diversity approved contractors with the government," Wollenberg explains. "We qualify because my wife, Carmen, is the president of the company; in Val Fab's case, the head of the company is a disabled veteran.

"But although that 'diversity' designation might get us in the door, I know it's the quality of our work that keeps the projects coming in," he says. "We handle the repetitive work while Val Fab does the large pieces. The big defense contractors know they can count on both of us."

Productivity By Design

Keith Doszak, plant manager, Performance Welding, says the XMT Series inverters were their primary machines during the fin project. "Re-work was not an option on this job. We were running 14 hours a day straight for those three weeks, except for Sundays, which were eight hours. We had six guys welding full out in two assembly lines; one to tack weld, one to weld the stainless steel boss to the mounting bracket, and the third guy welded the hardened steel fin to the boss. We were burning the coals on that job."

The defense fin project represents a prime example of how Wollenberg and Doszak have designed the production facility to handle repetitive projects. The physical layout of the facility, combined with the expertise of the welders, makes Performance Welding as productive as companies with many more fabricators.

"You do not need a lot of people to excel at high-volume part assembly," says Wollenberg. "With good welders and reliable equipment, and a system everyone embraces, Performance Welding has found its niche."

Wollenberg explains that high-volume production--typically projects involving a minimum of 50 pieces in the run and occurring at least three or more times per month--is set up in stages working from the rear of the plant, where the parts enter, to the front where completed assemblies are powder coated and painted.

Parts first go to the tack cell where they are placed in the necessary fixtures, put on carts and tack welded. At the next stage all sub-assembly welds are accomplished. Then the work moves to the third stage, final assembly, before painting and shipping to the customer.

Adaptable Equipment

The key to making the assembly process work, according to Wollenberg, is the operators' ability to select weld programs "on the fly" via the trigger on the welding gun, during sub-assembly using the Miller 70 Series wire feeder. "The feeder has a Trigger Program Select feature which allows my guys to weld on different materials during subassembly without adding another entire operation," he says.

As an example, Wollenberg explains one project involves welding on 14-guage square tubing, just 0.083" thick, then switching to 3/8" material on the same part. "The operator can use a short-arc setting, 18.5 volts at 250 inches per minute (IPM), for the first weld, then click the trigger for a thicker spray setting, 25.0 volts at 430-450 IPM, for the second weldment," he says. "We make good time, with good quality welds, and avoid adding a whole separate operation."

Doszak also points out that the company builds all of its own fixtures. "When we get a project we design the fixtures for simplicity and speed; the more welding that can occur in the fixture the better," he says. "That way we can eliminate unnecessary tacking operations."

Efficiency is the key, according to Wollenberg. "When you don't have 30 guys in the shop you look for ways to shorten lead times by doing as much sub-assembly work in advance as possible," he says. "And you ensure your people have the best equipment to accomplish their tasks--whether it's hydraulic lift tables and welding positioners, or inverters and accessories that improve their productivity."

Meeting Tolerances

For the APC fin project, cycle time of the inverters was critical, according to Doszak.

"The longest weld we made was about three inches; most of the work was a two-inch stitch every two inches, so we made ourselves spreader bars with tick marks every two inches to mark the weld spots," he says. "Once we got going we could really move quickly along the mounting brackets; we had no problems with the cycling of the machines." A high number of On/Off cycles places a lot of stress on welding machines, so it is one of the better performance indicators.

Doszak says they selected 309L, 0.035" diameter wire for the stainless work. For the high-tensile steel, they used ER 100 wire at 0.045" diameter. "We experimented with 0.035" and 0.045" ER 100 wire, running C5 gas (95% argon/5% C[O.sub.2]), and we found we gained a lot of time by going to the 0.045" wire," he says. "The Miller XMT 350 inverter was greatly improving our deposition rates--so much so we could run between 400 and 450 inches per minute and still maintain the contractor's tolerances. The welds were beautiful."

As quickly as his fabricators had to work, Wollenberg says the contractor's inspection process was the most important aspect. "To ensure that quality procedures were being consistently followed, the initial five pieces--and randomly selected pieces thereafter throughout the process--were inspected by a military-certified inspector using a coordinate measuring machine."

Each mounting bracket contained eight deflector fins. If each fin's positioning was off by as little as one millimeter, the entire piece would be eight millimeters out of tolerance. Miller Electric Mfg. Co. or Circle 205 for more information

RELATED ARTICLE: Working Through Dirty Power

Performance Welding's rural location has presented the company with some formidable power problems.

Before relocating to Freedom, WI, the company was in nearby Little Chute, where its power was hydro-generated from the waters of the Fox River. Dirty power was a constant concern. On numerous occasions, the unreliable hydropower would dim the lights in the shop.

Kurt Wollenberg, vice president of the seven-person contract fabricator, says, "The Miller XMT 350 with Auto-Line performs as advertised. It has shown the ability to ride through voltage drops, which can shut down our XMT 304s, and maintain a steady arc. That was critical during a recent project we completed for a national defense contractor." (see main story)

During that project, the problem became plainly evident when a voltage drop caused two of the three XMT 304s on the job to register low incoming voltage readings and shutdown for self-protection.


"But the XMT 350 with Auto-Line never hiccupped," Wollenberg says. "We were running 350 amps at 27 volts, 60% duty cycle, welding 3/8" hardened steel, and every piece met the defense contractor's tolerances of plus-or-minus 3 millimeters. The ability of the XMT 350 to ride through the voltage drop that shut down the XMT 304s was proof-positive to me of Auto-Line's benefits."

Even in a new location with more reliable power, Wollenberg says Auto-Line provided an advantage. During a winter storm, a power line crashed down across a major highway, causing the power grid to his facility to momentarily stumble. Again, his XMT 304s registered low incoming voltage readings and shut down, but "the XMT 350 rode through like a champ," he says.

Wide Tolerance

Auto-Line technology, unique to Miller Electric, provides fabricators with three key benefits that improve welding performance: the ability to maintain a steady arc despite primary power fluctuations within a 190 to 630V range; a primary power draw of just 17.8 amps at rated output of 460 VAC primary (a 25% advantage over competitive inverters); and the flexibility to accept any type of primary power--190 to 630V, single- or three-phase, 50 or 60 Hz--without any physical linking mechanisms. To put things in perspective, the line voltage compensation for the XMT 350 with Auto-Line is not just the industry standard of plus-or-minus 10%. Rather, it is plus 37% minus 59% of the nominal 460V power. This wide tolerance is unheard of in the industry.

"In our rural location, primary power will always be a concern. By using inverters like the XMT 350 with Auto-Line technology, we'll be able to specify smaller fuses and breakers, and smaller wiring, in our facility," he points out. "And we'll be able to add more welding machines without looking to boost our incoming service."
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Title Annotation:Welding/Brazing/Soldering
Publication:Modern Applications News
Date:Jun 1, 2004
Previous Article:JIT without the planning requires nimble machining: meeting the equipment demands of the oil and gas production industries places a premium on shop...
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