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Axcess System™ with Accu-Pulse™ Pulsed MIG Technology Lowers Weld Costs by as Much as $2,000/Day for OEM Fabricators

Executive Summary

OEM Fabricators eliminated downtime associated with grinding spatter, chipping slag and changing welding processes by standardizing on one wire, one gas and one welding system for nearly all its mild steel weldments. Miller’s Axcess system allowed OEM to switch from MIG short circuit transfer and flux cored welding to Pulsed MIG with minimal training and extreme results:

Axcess System Lowers Weld Costs by up to $2,000 Per Day

· Grinding spatter, chipping slag eliminated

· One wire, one gas, one system for most welding

· Fewer trips back to the welder for adjustments

· Less weldment repositioning

· Improved operator-to-operator consistency

Any manufacturer or fabricator wondering if best practices such as "kaizen" and "5S" produce tangible results need look no further than OEM Fabricators of Woodville, Wis. Kaizen is a Japanese word for continuous improvement, and kaizen events are continuous improvement projects used to eliminate waste. 5S (Sort, Simplify, Sweep/Shine, Standardize, Sustain) is a technique for visual work place organization and standardization where any tools and materials not needed for the job are removed.

Putting kaizen and 5S into action in May of 2004, OEM Fabricators has since streamlined operations by standardizing on one wire, one gas and one welding system for nearly all mild steel weldments, from 1/8-inch to unlimited thickness. Where an ER70S-6 wire provides acceptable mechanical properties, OEM Fabricators now uses .045 ER70S-6 wire, 90/10 argon/CO2 shielding gas and the Accu-Pulse™ (GMAW-P) welding process provided by 28 new Axcess™ multi-MIG welding systems from Miller Electric Mfg. Co. 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.

In addition to the kaizen and 5S principles, keys to OEM's successful process change included:

* Manufacturing engineer Scott Exner taking ownership of and championing the process change with support from company owners Mark Tyler and Jim Hauschild.

* Exner's training program to convert operators to the new welding equipment and process.

* The fact that the AccuPulse process adapts to the operators, allowing them to maintain their arc length preferences.

* OEM's belief that customers and vendors should be an extension of each other, including welding supply distributor Oxygen Service Company of St. Paul, Minn.

OEM Fabricators serve 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 fabricates numerous components from carbon steels, such as ASTM A36, A572, A514, A500, A513 and 4130; both 316 L and 304 L stainless steel and 6061-T6 aluminum. The company's motto is "To enhance our customer's ability to succeed." As a part of this approach, 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.

 

OEM operator Brad Henze says, You can control your arc length more effectively with AccuPulse. The technology in this machine far outrates older pulsing technology. Its very easy to learn.

The 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 old technology it was often required to use 75/25 argon/CO2 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 percent CO2 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 Exner. "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. 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. The ease and efficiency of the Miller AccuPulse process over short circuit transfer and FCAW has allowed us to substantially reduce waste in our manufacturing process. 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."

These things run smooth, says OEM operator Jim McIntyre (above). I wouldnt ever want to go back to the old way. And believe it or not, when I hit a tack weld, [AccuPulse] just burns right through it and lays a nice bead with no stubbing.

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 manufacturers.

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."

He continues, "When Oxygen Service Company representative Herb Peter called me to tell me about Miller's newest pulsed MIG system, he told me it was the best in the business. I've heard that story 800 times before from other salesmen, so I was really skeptical."

Exner went to a demonstration, coordinated with Miller district manager Mark Salz, with a plan to give Axcess 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-inch 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. 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, so it will match any service application 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). The AccuPulse 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 AccuPulse to perform with very short arc length characteristics that optimize welding performance and operator appeal. (Fig. 1).

As good as AccuPulse is, 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-degree day with 100-percent humidity and watch a 6,000-degree 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."

Exner's training program consists of Word and PowerPoint documents and video clips that discuss the basic transfer processes and consumables. Exner walks groups of six to eight people through the advantages and disadvantages of each process, then goes on to explain the equipment: how to turn on the power source, set up the wire, set machine parameters, strike an arc and perform basic arc tuning.

As Exner moves into explaining GMAW-P, he shows a video on old pulsing technology that goes through the mathematics of calculating peak and background currents. "I give everybody a note pad and have them start taking down the facts, figures and calculations," he says. "A lot of them get frustrated and think it's the end of the world. Then I shut the video off and say, 'Throw your notebook away, you don't need it.' That delivers the message that Miller's new GMAW-P technology isn't hard." Exner then takes the group to a new GMAW-P system on the shop floor and shows them how to set up a program, adjust arc length and arc control and set wire feed speed.

"The Axcess/AccuPulse combination further simplifies training because it adapts to individual operator preferences and does not force the operator to adapt to the machine," Exner states. "Typically, operators prefer to hold a short arc length(about 3/8 inch for short circuit GMAW and 5/8 inch for FCAW(because it gives them better control over the molten weld puddle. With older pulsing technology, different arc lengths sound, feel and look different.

"Conversely, AccuPulse keeps the arc length the same. It doesn't matter what you do with travel speed or how much stick-out you hold. This is a big benefit when welding corners. It lets you come into the corner with a push technique, then move out of the corner with a drag technique. There's no worry about the arc stumbling and the porosity that could result. You don't have to waste an hour grinding out a bad weld and repairing it."

OEM welder Brad Henze previously used a traditional inverter welding machine combined with the Miller 60M before switching to the Axcess system and had some good things to say about his switch.

"It was a total difference," said Henze. "The welds are a lot smoother and penetration is better. You can control your arc length. I've actually pulled it away about 2-1/2 inches before the arc goes out. The technology in this machine just far out-rates the 60M."

"It's very easy to learn," he added. "If somebody was afraid of going to an advanced technology machine like this, I would tell them not to be scared at all. The benefits are unbelievable for the puddle and arc control. I feel it puts me more in control as an operator and it's a lot easier and quicker. You don't have to walk away from the material and reset parameters because of the trigger program select. And no one can mess with your settings because the program is always there."

Jim McIntyre, another welder working at OEM was using an older thyristor controlled machine and had a similar experience with Axcess and AccuPulse.

"These things run smooth," he said. "Just look at the welds. We couldn't lay a weld down like that before. I wouldn't ever want to go back to the old way. We're just running hard wire on these and there's a lot less smoke. And, believe it or not, when I hit a tack weld, it just burns right through it and just lays a nice bead in there with no stubbing it at all."

Customers See Benefits

With the ability to set weld parameters, all operators working with the Axcess 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."

Peter adds that, "Another thing OEM found to be a big plus is that Axcess is upgradeable. Because welding processes and arc performance in Axcess are created and controlled solely by computer-type software, the hardware remains a fixed investment while the software enables upgrades as welding needs change."

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' 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."

AccuPulse Pulse Spray Transfer Benefits OEM

In theory, with the GMAW-P waveform, the peak current pinches off a spray-transfer droplet and propels it toward the weldment for good fusion. The background current maintains the arc but is too low for metal transfer to occur. With no metal transfer, the weld puddle gets a chance to cool, providing out of position spray transfer welding capability. The degree of this benefit is determined by the ability of the power supply to sense and respond to variation in contact tip to work distance and change the pulse frequency accordingly. Most pulsed systems use this technique today with the exception of the Miller Axcess System featuring AccuPulse. AccuPulse allows the current to regulate itself within a specified range at peaks and background, maintaining constant voltage and automatically adapting to changes in contact tip to work distances. Therefore shorter arc lengths, more control and increased usable process wire feed speed ranges are allowed. This ability enabled Exner to implement his "rule of ones": one wire, one gas and one welding system.

 

By using the Axcess 300 multi-MIG system with AccuPulse, operators at OEM Fabricators can complete a weldment such as this one, using one wire and one gas, with fewer trips back to the welder for adjustments and weldment repositioning.

It started by substituting AccuPulse for short circuit transfer. When the operator uses a slower wire feed speed, the system automatically produces a cooler arc. This allows OEM to weld its "thin" material; for them, this is steel 1/8 to 1/4-inch thick.

While AccuPulse can easily weld 1/8-inch steel without burn-through using a .045-inch solid wire, it is important to note that the pulse of peak current provides excellent fusion at the toes of the weld. Conversely, the short circuit process is highly susceptible to cold lap (cold lap is a weld flaw in which the hot weld puddle spills over the toes of the weld and does not produce the right penetration profile. When it occurs, the weld must be repaired). As an added benefit, AccuPulse has helped OEM increase travel speeds by 10 to 15 percent compared to short circuit MIG, and Exner sees the potential to reach 25 percent when parameters and operator education are optimized.

For welding thicker sections with AccuPulse, operators simply increase the wire feed speed and the system automatically adjusts other pulsing variables. Previously, OEM operators first needed to weld thinner sections with GMAW and clean up the spatter associated with short circuit transfer, then change wire and gas to weld materials above 1/4 inch. With FCAW, operators wasted time removing slag. Further, due to the nature of the large weldments at OEM, operators often needed to change welding parameters several times.

"If a guy is welding a 5-foot cube, he might have some verticals, some horizontals, some flat welds, some different joint combinations and different material thicknesses to deal with," said Oxygen Services Company's Peter. "With old technology, they might have to crawl out of a 20-inch hole to reset the welder or reposition the weldment six or eight times."

"With Axcess and its trigger program select (TPS), they set everything in advance," Peter continues. "Operators run sample pieces of those different joint combinations and find their preferred wire feed speed, arc length and arc control. Then, just by clicking the trigger on the gun, they can sequentially scroll through programs. They don't have to set the gun down or reposition the weldment. Whether they want a hot program with a wide bead for welding in the flat position, a cold program with a narrow bead for overhead welding or they need to go into a corner or around a circle, TPS allows them to select the program they want and weld without interruption."

Bulk Savings

With OEM now welding nearly all of its mild steel with a .045-inch ER70S-6 solid wire and 90/10 shielding gas and its high strength steels with a .045-inch E100S-1 solid wire and the same gas, Peter saw another opportunity for OEM to reduce welding costs: moving to drums of wire and installing a bulk gas system. It's a recommendation not every distributor would make.

"OEM's philosophy is to be an extension of our customers' design and manufacturing operations," says Exner. "We want to be part of their shop to add the most value. In turn, we seek to partner with companies who work with us the same way. We're all in the business to make money, but once we understand that and minimize purchase cost in the equation, we can both push forward."

Peter explains that a standard cylinder lasts OEM two or three days, and that OEM had to pay someone internally to manage 75 to 80 cylinders. With a bulk gas system (see photo), most of these costs were eliminated (OEM still uses argon cylinders for TIG welding and tri-mix gas for stainless steel). As for the filler metal, an OEM operator can deposit about 60 pounds of metal per day. Instead of using individual 35 or 60-pound wire spools where an operator spends 15 to 20 minutes per day changing spools, OEM now uses 600 and 900-pound 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 seven dollars a pound, where a solid wire that produces the same mechanical strength costs about four dollars a pound. Solid wire also increases deposition efficiency from 91 percent (FCAW) to 98 percent with pulsed spray transfer. Deposition rates are also higher, in excess of 10.8 pounds per hour.

"Although we make less money, the benefit to OEM was always the primary concern. We did what was best for the customer," said Peter. "With their uses and demands, it was kind of a no-brainer moving to a bulk wire and gas system and shifting from FCAW to solid wire."

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. Further, the welder gets bragging rights at the local hangout.

"Hey Joe, what welder are you using? What, you're not running Axcess? You have to get one in and try it. It is so easy to run and makes my life so simple!"

For more information on Axcess and AccuPulse, visit www.MillerWelds.com/AMS. For more information on OEM Fabricators, the kaizen and 5S principles and the leadership principles of Colin Powell, visit www.oemfab.com.

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