Eliminating the control cable
As a manufacturer of welding equipment used in crowded, bustling work environments such as shipyards and construction sites, Miller Electric Mfg. LLC has made strides to eliminate cords and cables. In applications that require Metal Inert Gas (MIG) welding, welders often work with wire feeders connected back to power sources by as much as 200 feet of weld cable.
If a welder wanted remote voltage control capabilities in the past, he/she had two primary options: walk all the way back to the power source or use a remote feeder connected back to the power source by a weld cable and a separate control cable. The first option proved inefficient while the second option required expensive control cables prone to damage in industrial environments. That control cable also provided one more piece of clutter to trip over or get tangled around equipment. With these challenges in mind, Miller designed a solution that transmits the welder’s control commands containing the desired welding operational parameters across the weld cable, eliminating the need for the extra control cable.
How it works
The technology, which Miller markets as ArcReach, is available two ways: either built in to the power source or as a separate control box that connects to the power source. ArcReach uses advanced digital serial communication technology to send voltage commands from the wire feeder to the ArcReach Control over the welding cable—the same cable that carries the welding current from the power source to the feeder. This is critical as it gives welders remote control of their voltage, which they regularly adjust to compensate for changes in material thickness and joint orientation.
The ability to transfer this type of command directly from a wire feeder to a power source over a weld cable was previously available but relied upon pulse width modulation. This limited the amount and variability of data transmitted in this manner, hence the need for a separate control cable. The new technology relies on phase shift keyed (PSK) modulation, which substantially increases the amount of data transferrable across the weld cable. The information communicated to the power source may include welding power source output command information (amperage/voltage), welding circuit on/off information (power source output contactor control), and power source state control (constant voltage/constant current).
While a seemingly simple concept, this improvement is valuable for three reasons: improved productivity, improved safety and reduced costs. Welders will spend more time with the arc on versus walking back and forth to the power source (and will be less tempted to rely on workarounds to finish a weld). Keeping the operator in the work area minimizes exposure to the elements and the hazards of the jobsite (climbing ladders, tripping), and eliminating the control cable reduces a major source of cost and downtime due to repair. Early adaptors of the technology are already seeing its benefits:
“It’s approximately five to ten minutes any time an employee goes to adjust their machine. With the welders being able to stay in their work location and change voltage right there, we can anticipate that they’ll be able to weld at least an additional half hour per shift each day,” says Walt Stokman, production coordinator, Gunderson Marine, a Portland-based shipbuilder.
Improving quality control through accurate voltage readings
There is also a quality control benefit: the ability to read actual voltage levels on the feeder’s digital meter when welding great distances—often hundreds of feet—from the power source. Voltage levels drop over long distances, but being able to see the actual voltage level as it exists at the point of use allows the welder to adjust the voltage accordingly to compensate for the drop. This ensures operators are always welding to the proper parameters. Similarly, foreman and supervisors can easily see that their operators are welding within those parameters without having to calculate a drop.
Simply put, the voltage at the output terminals of the power source (where the weld cable connects to the power source) may be significantly more than the voltage across the weld cable at the wire feeder. Accordingly, this technology enables an operator to modify the command signal that is sent back to the welding power supply via the weld cable, so that the losses experienced across the weld cables are properly compensated . The end result is that the user gets the voltage level at the weld they need. The digital meter displays this level, so the operator always knows the accurate voltage level.
Sidebar: new remote voltage control technology improves productivity, parameter settings and safety for Gunderson Marine
Shipyards present a welding environment that’s unlike any other. Shipyard welders encounter almost every position and type of joint known to man. This requires the ability to adjust weld parameters on the fly. Unfortunately, this capability also requires the welder to walk all the way back to the power source — often hundreds of feet away — or use a remote control wire feeder that needs an extra control cable to run all the way back to the power source. These cables are expensive and prone to damage—a costly addition when you take into account the hundreds of welding arcs typically found in a shipyard.
Gunderson Marine (Portland, Ore.), like many shipyards, wrestled with the durability of cables and connections, the counterproductive time spent managing miles of cables spread throughout the yard, and process annoyances such as voltage readings at the feeder that didn’t account for the voltage drop across long stretches of cable. Gunderson addressed these problems by adding the new XMT ArcReach System from Miller Electric Mfg. Co. This new technology transmits data across the weld cable, including voltage controls, and eliminates costly cords and the inefficiencies previously related to changing weld parameters.
Gunderson relies on multiprocess welding inverters because they are compact and require a relatively low power draw. A 450-amp unit at 100 percent duty cycle (Gunderson uses Miller’s XMT 456) is fairly typical in this application, and it gives them the capability to go up to 600 amps, weld heavier material and carbon arc gouge with up to a 3/8-in. carbon. The compact size allows Gunderson to pack the machines together on racks and ultimately plug into a single outlet. They have positioned dozens of these racks, containing anywhere from four to eight power sources, in strategic locations throughout the shipyard. Each power source is matched with a suitcase-style wire feeder typically capable of holding a 12-in. spool of wire.
“Our employees like suitcase-style feeders because it is easy to move the feeder from location to location within the barge,” says Stokman. “The wire is also covered, so we don’t have to worry about elements such as dirt and moisture getting on the wire. Having the wire covered also ensures there are no arcing problems, such as when an exposed spool of wire arcs out on the framing inside of the barge and you have a bird’s nest.”
It is the connection between the power source and the wire feeder that has presented the greatest inefficiency in the past. In addition to the regular welding cable that stretches out to the point of use, an additional control cable that connected the wire feeder to the power source was required to manually adjust voltage levels at the feeder. Gunderson tries to keep the distance between its power sources and feeders no longer than 75 ft., but it’s not uncommon to see distances anywhere from 100 to 300 ft. in other shipyards. The cost and handling of these cords is substantial. That control cable also provided one more piece of clutter to trip over or get tangled around equipment.
“With our previous remote control feeders, we were not happy with the control cords,” says Stokman. “As you moved feeders repeatedly throughout the vessel, the cords would break and the feeders wouldn’t work properly. We’d have to change out the feeders or change out the cords, which was very time consuming.”
Equally inefficient was the task of changing voltage settings as the welder moved from joint to joint. If a welder wanted remote voltage control capabilities in the past, he/she had two primary options: walk all the way back to the power source or use a remote feeder connected back to the power source by a weld cable and the separate control cable.
“We were looking for a way to make our welders more efficient,” says Stokman. “In order to change voltage, our welders currently have to leave the area, they have to get out of their gear, then move from the location they are working at inside the vessel to the outside of the vessel. In the time it takes to adjust their machine and work their way back, they may run into a coworker and talk for a few minutes. It’s approximately five to 10 minutes any time an employee goes to adjust their machine. With the welders being able to stay in their work location and change voltage right there, we can anticipate that they’ll be able to weld at least an additional half hour per shift each day.”
Our welders are now able to start at point A, work towards point B and adjust their settings for the different applications as they move from point to point. Previously, the welders would pick all of the horizontal welds and weld out two or three sections of those, then take off their gear and leave the vessel to change their settings, then come back and take care of all the verticals. This made it easy for welders to skip areas because they were constantly jumping around. A welder is now able to weld everything as he goes.”
“An additional benefit that we anticipate from this technology is safety,” says Stokman. “With the welder being able to stay at their station, they no longer have to traverse across frames, across stiffeners, through holes, through scaffolding, up ladders. Workers are able to minimize their traveling within the vessel, minimize exposure, thus making safety much better.”
There is also a quality control benefit to the technology: the ability to read actual voltage levels on the feeder’s digital meter when welding great distances from the power source.
“It allows the supervisor to check the welding parameters right at the location,” he says. “The supervisor can see the position that the employee is welding in and that the parameters are set at the optimum settings that we have developed.”
The new feeders also feature a built-in meter that tracks arc on-time, which allows supervisors to monitor the productivity of their welders throughout the day. While a seemingly simple addition, having this data helps the company understand its workload and properly bill/estimate its work.
“We can check productivity levels of our welders throughout the course of the day and find out what their arc times are and build off of that,” says Stokman. “We can use that for quality purposes, productivity purposes and future work to where we can bid our projects aggressively knowing what our efficiencies are.”
Overall, Stokman sees the new technology fitting in with Gunderson Marine’s mission — providing the highest quality ship fabrication and doing it in a manner that keeps the company’s welders safe and happy.
“We have a dual culture of quality and safety here at Gunderson,” he says. “Our employees care about safety, and this new technology allows us to expand on that. We’re able to build further quality into the product and check to ensure that our employees are welding to their correct parameters throughout the day. It also shows our employees that we care about their safety and want to minimize their exposure to potential hazards as they move throughout the vessel. So it’s an investment in quality and safety for us.”
Note on product update: Miller® ArcReach® technology has been updated with even more capabilities that make it even easier for welding operators to save time