Set loose the juice

Electronics change how power gets to the gun

PRACTICAL WELDING TODAY® SEPTEMBER/OCTOBER 2002

September 26, 2002

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As in other facets of welding equipment technology, arc welding power sources are evolving as fabricators' needs change. Electronics is playing a large role in power source modernization as power source equipmentmakers begin to employ digital interfacing, Internet access, software control, and other innovations to these machines.

Whether it means they're easier to use, more portable, or make welds more predictably, power sources are being updated, and electronics are playing a significant role in their modernization.

"The current economy is forcing companies to re-evaluate the value of outsourcing components to fabricators to keep their own trained welders busy and on staff," said Tim Temby, business unit manager of Three Phase Systems at Miller Electric Mfg. Co., Appleton, Wis., a manufacturer and provider of welding supplies and equipment for light to heavy industrial applications.

"As a result, organizations that have specialized in general fabrication are being challenged to prove they can provide the components more cheaply or with more value than can be provided by the OEM," Temby said.

And for fabricators, as for any other business, staying ahead of the competition is the primary concern. New technology can make welding more cost-efficient, faster, and higher-quality.

Expanding Power Source Versatility

Manufacturers of arc welding power sources are introducing technologies designed to make equipment more versatile for multiple applications to help fabricators face some of their most pressing challenges.

These challenges include providing lower-cost, higher quality-products; working more efficiently; competing globally; and working with fewer skilled workers, according to Chris Hsu, manager of applied technology, The Lincoln Electric Co., Cleveland.

"Fabricators need machines that are versatile and can handle multiple applications," Hsu said. "The equipment should facilitate a fabricator's ability to grow and expand his business by enabling him to take on new jobs and new applications."

Simplicity. For example, some emphasis has been placed on simplifying the user interface and making equipment more flexible, according to Dave Stanzel, business unit manager, Advanced Technology Products, Miller Electric. But this can be complicated, he said.

"This is a challenge because increasing the flexibility usually means more features, which in turn complicate the user interface," he said.

Bernie Beaudoin, product manager for high technology products for Lincoln Electric, said that his company's attention to the interface extends beyond the operator to other function interests at a customer's operations.

"Equipment must be user-friendly, with a simple user interface for interaction between the welder and the welding system," he said. "However, we are working to harness the technology to assure that the user interface provides second- and third-level controls designed to address the needs of other users, such as supervisors; welding engineers; and personnel in quality control, service, purchasing, and management."

Arc Start. Improvements in arc starting is another evolution, according to Tim Nacey, general manager of the Industrial Division of Panasonic Factory Automation, Franklin Park, Ill., a manufacturer of robotic arc welding components, including power sources.

"Most traditional power supplies employed almost no special starting capability. Recent generations of power supplies that were to be used frequently for robotic welding used precharged capacitors to apply starting voltage to the wire to create arc ignition," Nacey said. "However, even as this improved operation, it was recognized that a lack of a closed-loop response and feedback opened up areas for improvement. New technologies employing a capacitor discharge and a closed-loop feedback of amperage and voltage during starting achieve exceptionally high certainty of positive arc starting and likely reductions of arc starting-related instability and problems."

Productivity. Other power sources can control welding by employing digital communication, according to Hsu.

"This new equipment can be connected to factory automation systems using digital networking and Internet technologies," he said. "All of the system components communicate digitally. Versatile automation applications are possible because of the easy availability of information. Productivity, quality, and system performance may be monitored and metrics may be reported via optional communication modules."

Fronius, a Brighton, Mich., developer and manufacturer of products for welding technology, battery-charging systems, solar electronics, and plasma technology, has been delving into the world of digital welding sources as a way to help fabricators deal with an increasing need to join lighter and stronger materials.

"Welding machines have been basic machines that require a lot of manual input and knowledge," said Gary Baum, director of business development in marketing and sales at Fronius. "As materials and new crash test and impact standards develop for automotive applications, it's almost rocket science. The material gets thinner, and the weld strength has to be controlled."

To help fabricators with this trend, Fronius writes procedures for certain wires that will be used in various positions, welds, metals, and thicknesses. These programs can be sent via e-mail to a fabricator in the field, who can download them from a laptop computer to the power source.

Process Controls

Arc welding power source manufacturers say that developments they're seeing in the equipment they make provide more process control.

One such advance is wider operating ranges of wire diameters, which can reduce setup and changeover time, according to Stanzel.

Another improvement is the use of electronic controls with digital functions, according to Joe Hilt, outside sales manager for welders at MQ Power, Rancho Dominguez, Calif., a division of Multiquip that makes welding machines and generators.

"We're seeing the incorporation of high-quality electronic controls with digital functions," he said. "In the future, these functions will need to be operated with a remote control as a digital interface."

Additionally, power sources for robotic welding are evolving to provide more efficient wire stick detection, according to Nacey.

"Traditional, general-purpose power supplies with analog interfaces rely on sending a signal from the robot to the power supply to initiate routine end-of-weld functions, such as slowing of the wire feed speed, anti-burnback steps, and crater fill procedures," he said. "Then the robot confirms whether the wire is stuck to the weld by a relay-activated check of the voltage between the wire and ground. If there is an open voltage, the wire is not stuck and the robot moves on. This procedure typically requires an interval of 250 milliseconds."

In contrast, Nacey said, new-technology machines specifically designed for robotics and automotive welding applications don't wait at the end of the wire burnback time.

"It is assumed that the wire is stuck, despite the fact that 99.9 percent of the time the wire is free and not stuck," Nacey said. "At the signal indicating the weld is completed, a burst of voltage is sent to the wire, freeing it in those rare instances when the wire is stuck. The robot is then free to initiate the next programmed step after only 10 to 20 milliseconds as compared to the 250 typically required."

Another evolution in power supply technology is software control, which can free fabricators from the limitations of earlier power sources, according to Harry deCourcy, Midwest regional sales manager of Cloos Robotic Welding, Schaumburg, Ill., a producer of high-tech welding and cutting systems.

"Some power sources are fully programmable for whatever arc characteristics suit the operation, even to the point of being CV at one point in the wave and CC in another. Also, some power sources are now able to monitor arc conditions and respond to them," deCourcy said.

Additional Advances

Other power source developments include:

  • Network capability that allows fabricators to develop a procedure in the lab and download it directly to the power sources in the shop.
  • Self-diagnostics, which allow the power source to be fixed on the spot rather than removed and replaced.
  • Faster electronics, which permit quicker response to changing arc conditions and enable faster, more accurate seam tracking and touch sensing.
  • Tandem gas metal arc welding (GMAW) to boost productivity and deposition.
  • Single-sided welding for shipbuilding and heavy fabricated structures. This eliminates the need to turn the plate over and can eliminate air carbon arc gouging in certain applications. Flipping the plate over to ensure a complete joint penetration weld on panel lines in shipyards adds material handling time and increases the possibility of an accident.
  • AC-DC technology for multiple sub-arc and open-arc welding. Conventional sine wave AC output power sources operate at artificially high arc voltages to stabilize the arc and prevent arc outages, according to Beaudoin. "In multiple-arc welding, the phase shift between the arcs is controlled and can be set to increments in degrees from 1 through 360."

Technologies Users Want

Increasingly, fabricators are becoming more demanding of power source technology that can reduce spatter for production of cosmetically important parts. These parts range from thin-gauge sheet metal to 3 to 6-millimeter structural frames.

"Innovative waveforms based on arc physics to clear short circuits can reduce postweld spatter cleanup labor cost," Hsu said.Production robustness also is a major consideration when fabricators push for cycle time reduction. At high travel speeds, part fit-up, tooling tolerance, and welding distortion become more critical to weld quality in production, Hsu added.

"Another issue fabricators deal with is fluctuation in the primary voltage feeding the welding power supply," Stanzel said. "Many of the products on the market today have the ability to compensate for fluctuations in the range of ±10 percent."

He said Miller has addressed this problem by developing patented technology that allows the power supply to accept any primary voltage from 190 to 650 without reconnecting the power supply.

"One power supply can be used in any facility, and the user does not have to make any changes in the power supply to accommodate a different primary voltage," he said. "Also, most domestic users have either 230- or 460-volt primary power, and this technology can now accommodate changes in this voltage throughout the 190- to 650-VAC window."

Customization is a concern for fabricators that take on a larger variety of jobs that require many different welding processes, according to deCourcy. Because of this, Cloos is designing power sources that allow the user to tailor them for a particular operation.As always, productivity is another major issue now that fabricators generally are doing more with less. Currently electronics are being integrated into power supply designs to help improve efficiency.

For instance, Richard Shilling, vice president of sales for Arc Machines Inc., Pacoima, Calif., said his company is applying electronics to its latest power supply and controller. Arc Machines is a manufacturer of microprocessor-based welding power supplies and orbital and fixed weld heads for pipe, tube, tubesheet, and general fabrication.

"It's microprocessor-based, running on Windows® 98 with real-time digital data acquisition, multiple servo capability, and the ability to interface with our patented Arc Vision System," he said.

While productivity is important to fabricators, so is working in a clean environment, according to Hilt.

"The most common request from customers is to develop an environmental machine--a welder that provides superior performance but a welder with reduced emissions and lower noise levels. Environmental regulations will also require quieter machines," Hilt said.

"In any market that deals with an engine-mounted product, environmental factors are always an issue that must be addressed. Much as the automobile industry has been forced to comply with strict environmental standards, the welding industry will follow."

Baum said reliable inverter power supplies are helping the environment by being more energy-efficient.

"In a world that is focused on energy consumption, the inverter power supply has a lower power usage than a conventional power supply, doing the same amount of work," he said.

The Power Behind the Welding

Power sources not only command the electrical current necessary for arc welding, they might be able to improve productivity, depending on their design, power source manufacturers say.

The trend toward higher productivity is on the rise as fabricators strive to control costs as the number of skilled welding professionals declines.

More computerization, higher amperage ratings, more communication capability, and more storage for procedures are on the horizon, equipmentmakers say.

"Today's welding machine is expected to do more than just arc welding," Hsu said. "Its roles have been expanded to quality monitoring and assurance, coordination with motion control and robot functions such as seam tracking and adaptive fill, integration into factory automation networks, and digital integration with a multisupplier robotic marketplace. All this is made possible through digital communication technologies."

Practical Welding Today acknowledges the following sources used in this article:

Arc Machines Inc., 10500 Orbital Way, Pacoima, CA 91331, phone 818-896-9556, fax 818-890-3724, Web site www.arcmachines.com.

Cloos Robotic Welding, 911 Albion Ave., Schaumburg, IL 60193, phone 847-923-9988, fax 847-923-9989, Web site www.cloos-robot.com.

Fronius USA LLC, 10503 Citation Drive, Suite 600, Brighton, MI 48116, phone 810-220-4414, fax 810-220-4424, Web site www.fronius.com.

The Lincoln Electric Co., 22801 St. Clair Ave., Cleveland, OH 44117, phone 216-481-8100, fax 216-486-1751, Web site www.lincolnelectric.com.

Miller Electric Mfg. Co., 1635 W. Spencer St., P.O. Box 1079, Appleton, WI 54912-1079, phone 920-734-9821, Web site www.MillerWelds.com.

MQ Power, 18111 S. Santa Fe Ave., Rancho Dominguez, CA 90221, phone 800-883-2551, fax 310-604-3831, Web site www.multiquip.com.

Panasonic Factory Automation Co., 1711 N. Randall Road, E-ZIP 1E-10, Elgin, IL 60123-7847, phone 847-468-4000, Web site www.panasonicfa.com.



Stephanie Vaughan

Contributing Writer

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