+p one wire, one gas, one machine cut welding costs $2,000 per day: a Wisconsin Fabricator has found what might be the 'holy grail' of fabricating: one wire, one gas, and one welding machine for virtually all production welding requirements--and it saves about $2,000 per day.

Operating under the principles of kaizen to continuously improve and eliminate waste and the 5S Theory (Sort, Simplify, Sweep/Shine, Standardize, Sustain), OEM Fabricators (Woodville, WI) has streamlined welding operations by standardizing on one wire, one gas, and one welding system for nearly all mild steel weldments, from 1/8" to unlimited thickness. Where an ER70S-6 wire provides acceptable mechanical properties, OEM Fabricators now uses 0.045" ER70S-6 wire, 90/10 argon/C[O.sub.2] shielding gas and the Accu-Pulse[TM] (GMAW-P) welding process provided by 28 new Axcess[TM] multi-MIG welding systems from Miller Electric Mfg. Co. (Appleton, WI).

As a result, OEM has reduced welding costs up to $2,000 per day and is scheduled to pay for its new welding systems in approximately six months.

OEM Fabricators serves the needs of original equipment manufacturers, offering fabrication, welding, machining, shot blasting, painting, and assembly services. The company serves more than 80 customers in several industries, with a focus on those in construction and agricultural equipment manufacturing. It takes on projects for large original equipment manufacturers, fabricating their parts and optimizing their processes to make the parts more efficiently, with less cost and fewer variations. It fabricates components from carbon steels, such as ASTM A36, A572, A514, A500, A513, and 4130; 316 L and 304 L stainless steel, and 6061-T6 aluminum.

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Source Of Waste

Many of the welding procedures given to OEM Fabricators by its customers were established 20 or 30 years ago and haven't changed since. The weldments required for the fabrication of heavy construction and agricultural equipment often included a wide variety of different materials, joint combinations, and joint positions.

With older technology, it was often required to use 75/25 argon/C[O.sub.2] shielding gas using GMAW short-circuit transfer for thin sections and out-of-position welds, then switch to an all-position FCAW electrode and a 100% C[O.sub.2] shielding gas for thick sections in the flat and horizontal sections to complete the weldments.

"In addition to losing 15 minutes every time the operators stopped to change gas and wire, along with changing weld parameters, there's the clean-up time and the cost of grinding discs," says Scott Exner, manufacturing engineer. "Anytime I see a weld with grinding marks all over it, the first thing I look at, as a manufacturing engineer, is how much we paid a guy to do that. At the present time, approximately half of every manufacturing dollar is labor cost.

"Anytime we back up in the process, we've already spent that time once, and now the operator is doing it again, so it costs us twice," continues Exner. "Additionally, the operator is not getting done what he should be getting done, which equates to three times the labor for a given weld section. I calculated that a lot of our welding cells have lost up to 2.75 hours of productivity per 10-hour shift due to the older welding technology and its inherent disadvantages."

OEM has always tried to stay tuned to the leading edge of technology and had heard that GMAW-P could potentially eliminate productivity losses. In the past, the company tested Miller's inverter power sources paired with 60M feeders for GMAW-P, as well as GMAW-P systems from other manufactures.

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However, "Until the introduction of the Axcess system we had not found a welding system that would cover the diverse needs of our job shop environment, be teachable, and user friendly," says Exner. "I couldn't fine tune the arc without being a rocket scientist. With the technology being so complicated, the operators had a hard time learning it and in some cases the frustration level was so high that they would not accept the system."

Skeptic's Conversion

In his search for more productive equipment, Exner heard about the benefits of the new Miller pulsed MIG system from his welding distributor. Despite his skepticism, Exner went to a demonstration with a plan to give the new Miller system the ultimate test: Without changing wire, without changing gas, without changing but a few simple settings, he planned to make a fillet weld on 1/8" steel and then "hog trough" a weld--crank the wire feed speed to a level far beyond production speeds and make the fattest weld he could on heavy plate.

The Results?

Within two months, more than a dozen Axcess systems were in place at OEM.

The Axcess multi-MIG welding system is a digital system that combines flexible power conversion hardware with welding application software. It can produce nearly any physical arc characteristic or waveform that can be imagined, according to the manufacturer. A simple interface prompts operators to enter the wire type, wire diameter, gas combination, and process desired. The power source then selects the data from its library of application software to provide the best solution. After that, the operator selects desired wire feed speed and the system maintains a constant arc length throughout the appropriate welding range. Axcess power supplies are available in models that produce 300, 450 or 675-amp outputs, matching service applications from manual welding thin gauge material to heavy automated production runs.

GMAW-P Training

AccuPulse changed Exner's mind because it is more controllable and easy to teach. The AccuPulse process controls both current and voltage to stay within the optimum range for a specific wire type and diameter, wire feed speed, and gas combination (other pulsed spray transfer technology only controls current).

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The control scheme starts by ramping up the current. Once the target current is reached at the beginning of each phase, the constant current (CC) control turns off and the constant voltage (CV) control loop turns on. The CV loop modulates the current within a range that maintains the target voltage. This is independent of the contact tip-to-work distance, which allows the unit to perform with very short arc length characteristics, optimizing welding performance and operator appeal.

Exner knew that he needed to implement a training program to obtain all of the benefits this technology could provide his company. He notes that welding operators are special, as there are not too many people who will sit under the hood on an 85[degrees] day with 100% humidity and watch a 6,000[degrees] Fahrenheit arc on a hot piece of steel. And he adds, "after 25 years, they (welders) have an internal comfort level of feeling that they're in complete control of their world. Then when something new is presented, it completely brings them out of that comfort zone and could potentially make them look bad. They want to do a good job and they want the tools they know they can do it with, and now you're going to take that away. Before we could do that, we had to convince the operators that the new tool is actually a better tool, and to do that, they had to feel in their heart that it provides them with better puddle control."

Consistent Results

With the ability to set weld parameters, all operators working with the system "primarily use the same arc length and arc control settings," said Exner. "Once they set those two numbers, all they have to adjust is wire feed speed. This fits well with my 'one wire, one gas, one machine, one knob motto,' and is important from a quality aspect. With products for our customers, the first one now looks like the tenth one or the hundredth one. With older technology, we could not get the same operator-to-operator consistency."

As with many digital power sources and wire feeders, the Axcess system enables locking parameters within a set range specified by the engineer.

"Right now we're documenting programs for different cells and finding out what numbers work," Exner says. "Eventually, we will program the feeders down to probably two or three programs with locked ranges. This way, an inexperienced welder can hardly go wrong. Basically, he has to turn the welding machine on and weld. He doesn't have to get caught up in the engineering."

The ability to exchange software, or welding programs, already benefits one of OEM's largest customers.

"We do a great deal of work for a large manufacturer of construction equipment that also uses the Axcess system and AccuPulse process," notes Exner. "They can send us, via e-mail, a program that I can put on to my Palm[TM] and from there, we can program our welder. Now our guys weld exactly the same way their guys do, even though they're miles away."

Bulk Savings

With OEM now welding nearly all of its mild steel with a 0.045" ER70S-6 solid wire and 90/10 shielding gas and its high strength steels with a 0.045" E100S-1 solid wire and the same gas, Exner saw another opportunity for OEM to reduce welding costs: moving to drums of wire and installing a bulk gas system.

A standard gas cylinder lasts OEM two or three days, and OEM had to pay someone internally to manage 75 to 80 cylinders. With a bulk gas system, most of these costs were eliminated (OEM still uses argon cylinders for TIG welding and trimix gas for stainless steel).

As for the filler metal, an OEM operator can deposit about 60 lb. of metal per day. Instead of using individual 35 lb. or 60 lb. wire spools, where an operator spends 15 to 20 minutes per day changing spools, OEM now uses 600 lb. and 900 lb. drums and eliminates this unproductive time.

Moving from a flux cored to a solid wire also reduces costs. A typical high-strength E110T-1K3 FCAW wire costs about $7/lb., where a solid wire that produces the same mechanical strength costs about $4/lb. Solid wire also increases deposition efficiency from 91% (FCAW) to 98% with pulsed spray transfer. Deposition rates are also higher, in excess of 10.8 lb./hr.

According to OEM, the AccuPulse process is truly pulsed MIG perfected. "Pulsed MIG offered a lot of promise as far as benefits, but you never could get to the promises," says Exner. "Nobody could obtain the one wire, one gas, one machine benefit. Now there's a technology advanced enough to enable people to accept the benefits of pulsed MIG, without any of the drawbacks."

OEM's goal of one wire, one gas, one machine and one process has become a reality. Through the realization of this goal, Exner estimates that the company eliminates up to 2.75 unproductive hours per welder, per day. With a labor burden rate averaging $25 to $32 per hour, OEM has the potential to save up to $80 per day per employee. Miller Electric Mfg. Co.

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