As new defense contracts for armored vehicles began specifying Pulsed MIG welding with 307 stainless steel filler metal, Ultra Machine and Fabrication (Shelby, N.C.), didn’t wait for an order to update its facility. Before any contracts were finalized, Ultra added 32 new software-driven “multi-MIG” Axcess® welding systems from Miller Electric Mfg. Co. These systems would allow Ultra to weld MIL-A 46100 ballistic steel in all positions using Miller’s exclusive Accu-Pulse™ Pulsed MIG process.
The anticipation proved fruitful as Plasan Sasa (Israel) contracted Ultra to become part of the Oshkosh Defense supply chain to build components for its new M-ATV (MRAP All-Terrain Vehicle). The vehicle, similar to the MRAP (Mine Resistant Ambush Protected) units Ultra had already built parts for, is designed to absorb damage from improvised explosive devices (IEDs) and other roadside attacks without harming the crew inside.
Ultra has worked to make sure its equipment capabilities—be it a welder, a laser or a 2,000-ton press brake—are state-of-the art and more than capable of handling all current and future contracts. This foresight, along with a keen eye for shop layout (throughput optimization) and quality (74,000 parts shipped with only 23 defects), has allowed the company to keep ahead of fabrication trends. Adding an adaptable machine like the Axcess ensures the company will be able to add desired welding programs, for all materials, to the machine without having to buy new equipment.
“We didn’t want to find ourselves up against a wall,” says Bob Dawson, director of welding, Ultra Machine and Fabrication. “That’s why we chose the Axcess. We can update it with programs from the manufacturer and be ready to go instead of having to buy more machines. We’re really unlimited with what we can do with it.”
Frank Stewart founded Ultra in 1989 in a region rich with industry but lacking in advanced machining and fabrication. The company started out as a small parts manufacturer with the ultimate goal of building a full vehicle/capsule on its own. Stewart built the company’s foundation through loyalty to employees and a steady plan for growth that always put their best interests first.
“We’re a family-owned business,” says Stewart. “We’ve had great opportunities to invest in our employees. We have a chapel, we have a gym, we’ve always covered our employees’ healthcare and we do everything we can to keep employees healthy and happy while providing a really nice place to work.”
The company also invested in property that would support the anticipated growth. Current facilities exceed 300,000 sq. ft. With the MRAP project as a goal, Ultra built a new building in Shelby with high ceilings and 15-ton cranes. Next they added three Tanaka LMX VI laser cutting systems, a 2,000-ton LVD press brake, a fleet of Miller’s Deltaweld® 452 MIG welders, five high-definition plasma cutting tables and six robotic cells. The investment worked in Ultra’s favor: they secured the MRAP contract.
Traceability, Intelligent Workflow Ensures Quality
The new Shelby plant is built to ensure optimum throughput. Raw materials come in one end, are tagged and given a book to trace their path through the plant. Each process, whether it is forming, fitting or welding, is signed off by an employee ID number and initials. The book tells Dawson and his team when the part was built, who laser-cut it, who fit it, who welded it—every process from beginning to end is documented.
Materials come into the welding facility and are set in fixtures (Ultra builds its own fixtures to guarantee quality), then pushed on wheeled carts into any one of numerous identical weld cells. Welding procedures are posted in the cells and each welder works with an identical set of tools. The shop floor and workflow is designed in a way that is almost instantly adaptable depending on the parts working through the facility. All employees—from grinders to CWIs—are trained to inspect each part for quality as it comes through their station.
“We’ve had to learn to adapt to our customer’s needs through tooling,” says Gary Farmer, chief operations officer, Ultra Machine. “We’ve designed weld cells to increase our throughput. Our weldments are cleaned off-line. We’ve trained others, in addition to our CWIs, throughout the process to inspect the welds. We don’t bolt things down on our shop floor. We are always adaptable. We can move cells out, redesign them, make them bigger or smaller to fit our current workflow. It has really raised our quality level and increased our throughput.”
“Over the past eleven months, with the new M-ATV project, we have delivered over 74,000 individual components to our customer with only 23 rejects,” says Stewart. “All of the rejected parts were reworked. Our quality control, our checks and balances and our traceability has really maintained that 100 percent level of accuracy and we intend on keeping it there.”
Welding Armor and the Switch to Pulsed MIG
“Armor is a whole different animal,” says Dawson. “I’ve been welding for more than 30 years and never dealt with anything like this until I came to Ultra. It is totally different than any mild steel or high tensile structural steel. It has a memory that will not give up. Forming it is very difficult. Welding requires low preheat and inter-pass temperatures. Sequencing welds is very important when dealing with armor.
The tensile strength of MIL-A 46100 ballistic steel ranges from 252-288 ksi, compared to A36 structural steel which typically ranges from 58-80 ksi. Too much heat in the welding process changes the microstructure of the steel and takes away its armoring characteristics. It’s also susceptible to hydrogen-induced cracking. Ultra previously relied on Flux Cored welding, but specifications for the M-ATV vehicle required Pulsed MIG welding with a 307 stainless steel filler material.
Pulsed MIG provides more flexibility to control heat input compared to spray transfer or Flux Cored welding because it pulses between a high peak current and a low background current. Users of Accu-Pulse Pulsed MIG technology can adjust these and other variables to better control the weld puddle, heat input and other weld characteristics.
“One of the main reasons to go to pulsed is to get out of position with a hard wire,” says Dawson. “Depending on your gas mixtures and equipment, it’s very hard to weld vertical up with a regular MIG set-up. Another reason for Pulsed MIG is that maximum inter-pass temperature with MIL-A 46100 ballistic steel is 300 degrees. That’s where weld sequencing comes in, and pulsing also helps with the heat input, where a regular spray arc is a lot hotter.”
Upgrading the Fleet
Ultra still uses its fleet of Deltaweld 452s on mild steel components with E70S-6 MIG wire as well as other defense projects requiring the FCAW process, but most welding of armored steel is now done with Miller’s Axcess 450 software-driven multi-MIG system. Each unit is rated 450 amps at 100-percent duty cycle, and is matched with a four-drive-roll Axcess wire feeder. Axcess systems are capable of numerous MIG welding processes (including Accu-Pulse and Regulated Metal Deposition, or RMD™), and allows Ultra to continuously update the machines’ welding capabilities with new or enhanced programs.
“Our old MIG machines are only capable of a couple processes: regular MIG and Flux Cored,” says Dawson. “We wanted to have something that we could update and get Miller to help us write a program and get it loaded into the system instead of having to buy more machines two or three years from now.”
Axcess technology gives Ultra the ability to receive welding process upgrades via e-mail, the Web or a Palm™ handheld device. The ability to standardize all machines in the fleet on the same exact program simplifies training and ensures that all welds in this critical application are identical each time.
“Training was simple on these machines,” says Dawson. “The programs are loaded, the parameters are set and we have an operator lockout on there so that, no matter how many buttons they push, the machine will only operate within the parameters the WPS (welding procedure specification) requires. ”
The machines also feature Arc Control and Arc Adjust features that improve overall weld performance and appearance. Arc control tailors pulse weld programs by adjusting the arc plasma cone to accommodate a variety of welding applications without the need for any reprogramming or changing of hardware while Arc Adjust controls arc length for pulse processes and wetting action.
“You have more control over your arc with the Arc Control and the Arc Adjust than just changing voltage or amperage,” says Dawson. “You can actually dial the arc right in. You can make it longer or shorter, or you can make your cone wider. You can dial it in where there is little spatter, it runs as smooth as silk and you have very little post-weld cleanup.”
Each of these factors have simplified a complex welding process on critical components built for the sole purpose of saving lives. The ability to fine tune the Pulsed MIG process and to add programs for future contracts gives Ultra the flexibility it needs to be competitive in its marketplace without having to buy new equipment.
“From here on when we buy a machine, it’s going to be an Axcess,” concludes Dawson. “No matter if it’s a pulsed process or not.”