Company surpasses previous aluminum frame-welding technologies on a new supercar modeled after a classic winning racecar
Sixteen months is not much time to design and produce a production-ready street legal totally modern redesign of one of motor racing’s most legendary vehicles – in fact, it’s unheard of. But when the chairman of the Ford Motor Company, William Clay “Bill” Ford Jr., told his design and engineering teams that he wanted the new Ford GT ready for him to drive in the company’s June 16, 2003, centennial parade, it became job one.
The original Ford GT40 gained its reputation after company Chairman and CEO, Henry Ford II, became determined to end the dominance of European auto manufacturers in international racing. In 1966, the GT40 swept first, second and third place at the 24 Hours of Le Mans, the most prestigious of all international racing events. At the same time, Ford dethroned Ferrari which had won the previous six races. The GT40 would end up winning first place for four consecutive years. Before the GT40, no American car had won the event.
While the new Ford GT maintains the image of the original with its low profile, curving lines and mid-mounted engine, it has grown slightly in size. The new GT is 18-inches longer, nearly a foot wider, and four-inches higher than its predecessor. The engine, Ford’s largest 5.4-liter, supercharged V-8, generating 500 horsepower and 500 foot-pounds of torque, provides power almost identical to that of the Le Mans-winning legend.
To accomplish this feat of engineering mastery on such a tight timeline, 30 engineers were selected from the top of their respective departments within the Ford Motor Company, and given an off-site Detroit location where they could focus on the task at hand.
The next step was to pick trusted suppliers that could handle the demands of such a fast-track project and its inevitable fast-paced changes in design and other technical elements. Since the frame on the new GT would be an aluminum space frame, it was critical that Ford select a partner at the forefront of aluminum welding technology.
The Lincoln Electric Company had already proven its aluminum welding expertise to both Ford and subcontractor Metro Technologies, Ltd. Metro had previously called in Lincoln on another aluminum frame project for Ford called the Think vehicle. The Think was a people-mover concept vehicle that could be likened to a highly engineered next-generation low speed electric vehicle. With the Think project, partners Lincoln and Metro were able to demonstrate proof of their expertise on aluminum-framed vehicles, so when it came time to look for welding partners on the Ford GT project, Lincoln and Metro were given the task.
And quite a task it was – joining 35 aluminum extrusions, seven complex castings, two semi-solid formed castings and several stampings with over 450 aluminum welds, each one unique, to make up the hybrid aluminum space frame. Attempting this many robotic welds on an aluminum automobile frame was a venture into uncharted territory.
Rick Tepper, Robotic Welding Coordinator for Metro, said that his team was able to complete the daunting task through teamwork and comprehensive analysis. “Once Metro Technologies received the job, we worked with MVS (vehicle stampings and assemblies designer Mayflower Vehicle Systems) to develop a spaceframe design that was both structurally sound and capable of being manufactured. We applied knowledge from previous programs and developed a team of Tier 2 aluminum suppliers for additional support and expertise.
Tepper and his team, together with Lincoln as a source of welding expertise, also brought to the project years of collective experience from working on a myriad of aluminum welding projects. “Weld shrinkage, or distortion, can be a major factor when working with aluminum,” Tepper said, “but we knew, by experience and experimentation, how to weld these frames and keep distortion to within a couple of millimeters on the entire frame.”
“We’re talking about a high performance vehicle pushing 500 horsepower and going zero to 60 in four seconds with a top speed around 200 miles per hour,” Tepper says. “That’s why the welds have to be spot on.”
The key to manufacturing an aluminum frame with such a high number of welds is sequencing according to Tepper. By sequencing the robots to weld alternate sides of the frame, it allows an area to cool down before accepting another weld, thereby reducing distortion and controlling shrinkage.
To complete the job, Lincoln and Metro assembled four robotic cells utilizing a total of five robots. Lincoln’s Power Wave® 455M power sources were mated with FANUC® 120iLB six-axis robots with the longest available reach of 70 inches and capable of high speed movements. Each of these cells makes 100 to 125 welds. Rotating positioners were used to hold the parts under the robots to reduce cycle time.
To complete welding operations, the team chose Lincoln’s SuperGlaze® 1.2 millimeter 4043 aluminum MIG wire. The 4043 alloy can be tricky to feed because of its softness. To manage the feeding challenges, a Binzel® torch was used in conjunction with an MK Products® push-pull system. Argon was used as the shielding gas. All of these components were then integrated by Lincoln Electric, providing Metro with a single welding partner to take responsibility for the welding cells, equipment and operation.
“Lincoln Electric is the single source of supply for every aspect of welding on this project,” says Carl Occhialini, Automotive Manager for Lincoln Electric. “This is the only way the project on this timeline could work. I have seen situations where one person is responsible for the robotics, and one person is responsible for the consumables, and so on, and then when there’s a problem, everybody just starts pointing fingers instead of finding solutions.”
Before the welding began, Tom Larkins, Applications Engineer, Lincoln Electric Automations Division, utilized the Delmia (formerly Deneb) UltraArc® robotic arc welding simulation program to determine the logistics of the project. By programming in three-dimensional, virtual models of the robots, torches, cabling and the parts to be welded, real world placements of each component could be factored as could the movements of the robots to reach hard-to-access weld placements and avoid collisions.
“We used this as a tool as to whether or not specific components of the project would work,” Larkins, says. “Without this validation, the costs and timeline associated with the project would have been greatly extended.”
With the information provided by the Delmia program, it was up to Lincoln’s Robotic Technologist, Marty Sidall, to program the actual robots.
“There were a lot of challenges with the robots running upside down and it was difficult to get the torch into certain areas for some of the welds,” Sidall says. “In order to reach every single weld in the Delmia program, we were really pushing these robots to their limits of positioning and the placement of the parts had to be precise.”
The constant design changes also created programming challenges for Sidall. When one of the robot’s 40 to 50 weld positions had to be altered, it created a domino effect in the programming in that the entire sequence after that weld had to be altered. Adding to the complexities of the programming was the fact that two robots were welding simultaneously in the same cell which required “handshake communications.” In these cells, if a weld sequence was altered, it would have to be altered on both robots.
“You not only have to program the robots to do the welds, you have to program them to know each other’s location to avoid collisions,” says Sidall.
To do this, Sidall programmed one of the robots as the “dumb” robot, which would return to a perch position before the other robot would resume its sequence.
Additionally, because there were so many welds to complete, the clamps and tooling holding the parts to be welded were often getting in the way of the robots and the weld gun.
“Hats off to Metro. They were right in there at a moments notice, bending and cutting clamps and relocating clamp handles all to allow for the robots to do their job,” Sidall says.
All said and done, the programming of the robots for each cell took about six weeks.
Cell one utilizes one robot with what Occhialini calls a double Ferris wheel, where two fixtures revolve around each other and individually spin at the same time. Front and rear bumper mounts, transmission assemblies and miscellaneous stabilizing bars are mounted in this cell.
Cells two and three utilize two inverted robots each, or robots hanging from overhead, to allow for more range of motion. Rear sub-assemblies and primary castings are welded in cell two while cell three welds front assemblies.
Cell four utilizes two more inverted robots to weld together the front and rear assemblies and attach the cockpit, or greenhouse, completing the frame.
The Ford GT Spaceframe Manufacturing Team chose to use the Power Wave 455M because of its advanced Waveform Control Technology™, an element of Lincoln’s Nextweld® Technology innovations. Waveform Control Technology is Lincoln’s proprietary technology platform that controls and shapes the output waveform. Since the waveform may be shaped digitally, using software without the need to change electrical components, equipment with waveform control can deliver customized results for virtually any application, improving productivity, quality and operator appeal on a wide range of materials. These capabilities provide users with a versatile and upgradeable welding system.
In particular, Tepper said Lincoln’s patented Pulse-On-Pulse™ process was integral in allowing Metro to achieve the welds necessary on the 6061 T6 extruded aluminum ranging in thickness from 1.5 to 8 millimeters, with 3 millimeters being the most common size. Pulse-On-Pulse allows for a lower amperage welding procedure to be used, critical when distortion control is required for welding thin gauge aluminum. Also, the digitally-controlled Power Wave 455M inverter power source is capable of sophisticated arc starting procedures that help to reduce the risk of starting porosity and contribute to a flat, attractive weld bead profile. In addition, the Power Wave 455M, with Lincoln Waveform Control Technology™, allowed for seamless arc welding process changes from MIG (GMAW), to pulse or Pulse-on-Pulse from one weld to the next.
Tepper noted another benefit of the Lincoln equipment Metro was using, “With Pulse-On-Pulse, you don’t really get much spatter at all. There’s not much clean-up beyond wiping the weld clean.”
As for interfacing with the Lincoln equipment, Tepper said, “Actually, the robots, together with Lincoln’s control panels, are pretty easy to use. Once we (Metro, Lincoln and Ford) developed our welding procedures, we didn’t have any problems.” The whole process ran smoothly. Tepper said by the time they welded the fourth frame, they were running ‘production intent’, or parts intended for use in actual production, featuring weaved welds and all.
With the frame completed, additional trusted suppliers were depended upon to complete the dream machine: aluminum body panels – Mayflower; interior – Lear; electrical system – United Technologies Automotive; powertrain – Roush Industries; transaxle – Ricardo, Inc.
Three months prior to the centennial celebration deadline, nine prototypes of the finished car hit the road to test various components. By the June 16th deadline, three production models were ready and were driven, one by Bill Ford, to kick off the company’s centennial celebration.
Two of the original three GTs have been dedicated ‘media cars’ and are currently making the circuit of leading automobile media outlets where they are being driven and reviewed by journalists. An additional 15 GTs were built for crash, and other tests.
With the completion of the first 18 GTs, the robotic welding cells and other production mechanisms are being dismantled and shipped to Milford Fabricating Company in Detroit. Milford, a subsidiary of the Budd Company, will handle production of the vehicles. The plan is to build eight GTs per day, five days a week for two and a half years – a grand total of 4,500 GTs expected to retail at $140,000 – 150,000.
If initial feedback from the automotive press is any indication, the GTs should be zipping off the showroom floor faster than even their 500 horsepower engines can take them.