Issue: Older power sources experiencing excessive downtime and maintenance costs; justifying investment in a new welding fleet in an uncertain economy.

Solution: Energy efficient Invision 456MP and XMT 456 inverter-based welding power sources and 70 Series feeders from Miller.

Results: New inverters improve uptime by approximately 10 percent in fabrication work areas, while operators enjoy the comfort of feeder features like trigger hold and digital meters. Plus, a $47,000 rebate from the local utility company enabled the plant operation manager to justify a complete fleet changeover.

Some people have a higher threshold for pain; Norman Vautour is one of them. As production supervisor at Woods Equipment Company's Gardner, Mass. facility, Vautour was responsible for maintaining 18 ancient GMAW welding systems. Through his tireless efforts to fight downtime, the company continued to meet the demand for its Woods Wain Roy brand buckets and grapplers for excavators and tractor loader backhoes.

Wain Roy quick-change coupler systems permit changing attachments in a matter of minutes; operators don't even have to leave the cab when using the hydraulic version. Since the 1970s, Wain Roy quick-change equipment has helped contractors be more productive.

However, it wasn't until May 2002 that a change at Woods eased Vautour's pain—and improved productivity by 10 percent while earning a $47,781 rebate from local utility company Mass Electric. The improvements occurred when welding distributor Liberty Supply Inc., Leominster, Mass., installed efficient and reliable XMT 456 and Invision 456MP inverter power sources and 70 Series wire feeders from Miller Electric Mfg. Co.

Power Savings

The XMT 456 is a multiple process (Stick/TIG/MIG/flux cored/gouging) power source with a 5 to 600 amp welding output. The Invision 456MP is also a multiple process power source (Stick/MIG/flux cored/gouging) with a 5 to 600 amp output, but it features built-in controls for pulsed MIG, 18 factory-set pulsed MIG programs and one manually set pulsing program. The Invision 456MP is the easiest, most cost-effective industrial inverter to use for pulsed MIG.

Most importantly, the XMT and Invision have an average power efficiency of 85 percent. Where Woods' old machines drew 16 kW while welding with a .045 in. diameter E70C-6M metal-cored wire, the XMT and Invision draw only 9 kW. Depending on the function (fabrication or tacking) and whether they were used for one or two shifts, Mass Electric calculated that these inverters would save 1,599 to 65,542 kWh per year, per machine. Total power reduction was an estimated 111,407 kWh annually, which led to the rebate.

"The fact that Liberty Supply showed us how to obtain a rebate that paid for half of the 18 new welding systems made upgrading too enticing to pass up, even in an uncertain economy," says Bob Latour, Woods' Gardner plant operation manager.

In addition to the rebate, the new inverters will lower utility bills by an estimated $9,692 annually. "We've already seen our kilowatt usage drop," notes Latour. "The plant was using as much as 91,000 kW per month. After installing new inverters in May 2002, we used 87,000 kWh. It dropped to 81,000 kWh in June. The inverters are the biggest reason for the change."

Frustration and Downtime

While built to last decades, welding power sources have a finite lifetime. Woods continued to use its Hobart Mega-Flux and Excel-Arc welding systems beyond their reasonable life span in a high arc-on time application.

"The newest welding power source we had was made in 1981," says Vautour. "These old machines were constantly breaking down and we'd have to remove the machine from the cell and move another in. As a result of daily fluctuations in the output power, the welding wire frequently burned back into the contact tip. Between moving machines, burnbacks and grinding out bad welds, each fabrication operator lost an estimated 45 to 60 minutes per day of production time."

Liberty Supply representative Chris Kimbar adds that "old welding power sources often run hot one day and cold the next, and they don't have the ability to compensate for 'dirty' primary power. That's why Woods' operators spent a lot of time adjusting weld parameters and grinding out weld defects. Any time output voltage or amperage fluctuates, it affects the appearance or integrity of the weld because a welding wire needs to run within its proper parameters."

These problems and others meant weekly trips to Woods for Liberty Supply service technician John Matarese.

"I would go to Woods to replace rectifier fuses or install new or rebuilt boards," he says. "Sometimes it would be simple things like checking that the drive roll matched wire size or cleaning the bolts on the transformer voltage links. A lot of people don't realize that failing to clean carbon off the bolts can cause one leg of the power to be weak, which in turn overworks the other two legs, stresses their SCRs (rectifiers) and reduces their service life."

Matarese notes in the last few years of the old machines' life he replaced six to 10 auxiliary transformers per year. "Because Woods constantly shifted machines from station to station to provide operators with a working machine, the voltage links were sometimes set for 240 V power and accidentally plugged into 460 V primary or vice versa. That causes the auxiliary transformer to fail with a nice, loud popping sound."

Upgrading to Inverters

Efforts to squeeze another year of service from an old power source are the rule rather than the exception among many manufacturers and fabricators. Even though an old machine causes downtime, the prevailing mentality is "but it still welds." People like Kimbar are helping to change that mindset. By showing companies like Woods how today's inverter power sources and digital wire feeders increase productivity and quality, justifying the capital expense has become much easier.

"When older welding equipment goes down, a company's assets are sitting idle," says Kimbar. "We help companies understand the value of uptime offered by new welding equipment and equate that to getting more product out their door."

Operations manager Latour notes that "since we purchased the new welding systems there is less of a need for overtime. Our fabricators get about 10 percent more work done during their regular shift."

Woods' fabricators also appreciate equipment that makes their life easier. "The trigger hold function on the wire feeder really saves my wrist, and I weld for about five hours out of an eight hour shift," notes Jay Austin. Most of the buckets Austin welds have four 2- to 3-ft.-long welds (see photo, p.9) for welding on the mold board and side leading edges. "I like the feeder's four drive roll system because the wire doesn't hang up. On the power source, the digital readout is nice because I can view settings at a glance. I always had to tweak the wire feed speed or voltage on my old system because it ran differently from day-to-day. It's easy to see now, but I don't have to change it much anymore. With the new inverter, I just turn it on, start welding and continue to make clean welds all day long."

Power Savings Spread

While increased productivity, better weld quality and better uptime will, in the long run, provide a greater payback in energy savings, the utility rebate was the catalyst for change at Woods.

"The upgrade would not have occurred all at once," says Vautour. "It would have been spread over a couple of years, replacing the older machines two or three at a time." Latour adds that, "Through the energy efficient welding systems, we connected with Mass Electric's savings programs for things like lighting, air conditioning and compressors. None of this would have happened if it wasn't for Miller Electric equipment and the knowledge of Liberty Supply."