Submerged Arc Welding Gantry System Makes Crane Fabrication 4 to 5 Times Faster | MillerWelds

Submerged Arc Welding Gantry System Makes Crane Fabrication 4 to 5 Times Faster

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An automated gantry system with submerged arc welding saves up to 15 hours on each overhead crane build for WF Steel & Crane.
Submerged arc welding process on overhead crane box
Submerged arc welding gantry system for crane fabrication

SAW provides competitive edge

WF Steel & Crane specializes in structural steel fabrication projects and custom overhead crane solutions for industrial customers in western Canada and beyond. Since opening in 1987, the company has expanded from one facility to three in Nisku, Alberta, just south of Edmonton.

Today, overhead cranes are about one-third of WF Steel & Crane’s business, as structural steel projects continue to grow. The company’s structural steel projects include pipe racks and piping for compressor stations, while the overhead cranes — which range from 1/2-ton to 100-ton lift capacity — often go to manufacturing customers.

“We’ve sold cranes all over western Canada and in the U.S.,” says Ryan Schram, WF Steel & Crane co-owner and managing director. “Safety of course is paramount, but quality is right behind it for us. It’s important for us to get more production, but still maintain the high quality.”

In recent years, diversifying offerings and finding ways to improve productivity have been key, as the region’s economy has been significantly impacted by the downturn in the oil and gas industry.

“In Alberta’s current economic climate, the price is king,” Schram says. “We knew the only way to really make it was to be progressive and to spend the money to invest in the right equipment.”

The company converted to an automated gantry system with submerged arc welding (SAW), and it’s been a game-changer for productivity. In fact, they are now saving up to 15 hours on each large overhead crane build. The welding gantry is a twin wire, dual weld head system that includes two Miller® SubArc DC 1000 Digital power sources that use Hobart® filler metals.

“We can bid crane boxes a lot tighter than we used to. That means more profit for us, and at the current time we can compete a lot harder,” Schram says.

Previous system cost time and money

The company uses SAW for its overhead crane boxes because of the higher deposition rates and deeper penetration of the process. On crane projects, the company typically welds metals from 1/4- to 2-inches thick.

The shop was using a single-wire SAW process with a tractor that was not automated. The large crane boxes, which can be up to 150 feet long, had to be laid on their sides so each side could be welded separately. Because the heat was going to one side of the box, this caused the boxes to twist and warp, which required hours of post-weld work to heat treat and straighten the boxes.

“It’s a time issue, it’s rework,” says Darrin Jacobson, quality control manager at WF Steel & Crane. “It would range from half a day to a full day to get a girder straight again.”

The goal was to implement a different system that would eliminate these issues, to save time and money.

“We wanted to be able to compete, build faster, create more products and get more cranes out there,” Jacobson says.

Designing a SAW gantry solution

They hatched a plan to design an automated gantry system for a SAW process that could weld both sides of a box simultaneously while keeping the box upright to counteract warpage and the related productivity issues.

WF Steel & Crane contacted their Praxair Canada distributor, who connected the company with LJ Welding Automation. LJ is an Edmonton-based company that designs and builds welding positioners, vessel rotators, pipe and tank turning rolls, column and boom manipulators, along with many other types of welding automation equipment. With a full manufacturing facility in Edmonton, LJ had the skill sets and capacity to create a system to specifically meet WF Steel and Crane’s needs and goals.

“We all worked together to figure out what the best solution would be for them,” says Kyle Gratrix, director of welding applications for LJ Welding Automation.

In choosing the welding equipment to use in the gantry system, LJ recommended Miller SubArc DC 1000 Digital power sources because they integrate easily, which benefits communication and efficiency.

“Integration-wise, it was very easy,” Gratrix says. “If LJ Welding’s engineers had a choice, they would pick Miller SubArc on every system because of the compatibility. It’s seamless.”

WF Steel & Crane uses Miller equipment in other areas of the shop, so they trusted it would be a good choice for the automated SAW system.

“The Miller DC 1000 definitely has enough amps for the subarc, which was a big concern because we’re running twin wire, so we needed a big enough power source to run it,” Jacobson says.

The operator controls every part of the system — including the gantry and the welding power sources — using a touchscreen. The LJ software and HMI controls are the brains of the operation, ensuring the various components talk to each other and work together.

A user-friendly system

The operator sits in front of the touchscreen and uses a joystick to position the two welding heads. The operator has dual independent torch control, with 84-inch servo vertical cross slides that allow for a range of automated weld seam tracking. They chose the touchscreen interface because it’s compact and user-friendly. A human hand must activate the override joystick for the system, adding an extra layer of safety in addition to making welding head adjustability easy for WF Steel’s operators. The gantry’s weld camera system also uses laser pointers, allowing the operator to view the weld location through the touchscreen monitor. Once the operator inputs welding parameters and guides the heads into place, welding begins.

“On the touchscreen everything is pre-set already, so I can basically just hit the start button and it's ready to go. It's very user-friendly,” says Corey Lewis, the system’s operator.

A horizontal and vertical track drive laser seam-tracking system that is servo motor controlled monitors the length of the joint, automatically adjusting for any curvature or arc in the beam. WF has welded beams up to 150 feet long with the system, which completes one continuous weld with twin wires on both sides simultaneously.

“The tracking is important because these box girders have camber in them, so a box this long will have 40-millimeter rise and back down,” Lewis says. “The laser tracking follows the camber in the box, so it will be a consistent bead the whole length of the girder. You wouldn’t have a very good weld if it didn’t follow that rise and keep the weld consistent.”

Saving up to 15 hours per job

Because both sides are welding at once, the gantry system helps control heat input to reduce distortion of the beams. In addition, using twin wires on each side greatly increases deposition rates — more than doubling them from the old system.

Those productivity gains are combined with the significant time savings achieved by reducing the necessary heat treatment and beam straightening.

“I would say this is four to five times faster, not counting the straightening,” Jacobson says. “The new system has increased productivity, is a lot more user-friendly for employees and better quality.”

Previously, a 100-foot beam may have taken 12 hours to weld and four hours or more for heat treatment and straightening. Weld rates using the single wire and SAW tractor were 10 to 12 inches per minute.

With the new gantry system and automated SAW process, that same job can be completed in one to two hours. Using twin wires on each welding head results in a weld rate of 30 inches per minute.

“Before, that would have taken 15 to 18 hours, depending on repairs,” Lewis says.

Being able to complete crane boxes much faster makes WF Steel & Crane competitive for more jobs.

Choosing the right filler metal

Installing and fine-tuning the gantry system also required finding the right wire and flux combination. WF Steel & Crane tested metal-cored wire options before selecting a Hobart SubCOR™ EM12K-S solid wire. They use Hobart HA-495 flux for welding category 4 steels and Hobart SWX-110 flux for welding other materials.

“The slag release was the biggest thing,” Jacobson says. “The cleanup time was great, it had a smoother appearance on the weld. Once you find the right combination everything kind of falls into place where you have good weld appearance, easy slag release.” The flux delivery and recovery system used by WF adds further efficiency to the gantry solution by minimizing flux changeovers.

Expanding welding capabilities

The crane box fabrication process also requires an operator to weld inside the box with metal-cored wire. These flat horizontal fillet welds are completed with Miller XMT® 450 welders, which are also used throughout the shop to weld metal-cored filler metal and stick electrodes on structural steel projects. The company has about 20 welding stations in each of its three shops.

“I like how versatile it is. You can switch it from one process to another, and it’s not really a big task,” says Caleb Stansbury, a journeyman welder with WF. “It’s flip a switch, change the connections and away you go.”

Quality is critical in all of the projects WF Steel & Crane completes, so they need reliable machines that help operators produce quality welds.

The company also purchased two Miller XMT 450 MPa machines with S-74 MPa Plus wire feeders, with plans for adding different types of welding to their business capabilities.

“We’re using them for pulsed welding for out of position. In the past, anything out of position was done with stick electrodes, which is slow,” Jacobson says. “It’s just one more step that makes it easier where we’re not doing everything in position and rolling.”

Changing it up to stay competitive

Given the economic realities, WF Steel & Crane knew it was important to invest in new solutions and technologies. Companies looking for an edge must always be looking for a better way to do things.

“WF is a very progressive company. They’re always looking at new innovative equipment and processes,” says Mike Swainson, territory manager for Praxair Canada. “If they can increase the travel speed, increase the deposition rate — all of those things are going to give them a competitive advantage. If you’re going to do it the same old way, you’re probably not going to get the work.”

Investing in a more productive process or technology can provide the leg up a company is looking for.

“You have to do it if you want to be competitive,” Schram says.