With 53 engineers and 22 Doosan CNC machine tools, NASCAR’s Joe Gibbs Racing (JGR) easily has more technical expertise and production capacity than many mid-sized job shops. But it needs every bit of that capacity and expertise to do one thing – win races.
“The first year, JGR didn’t win anything, in fact, they pretty much tore up everything,” says Mark Bringle, technical sponsorship and marketing director, remembering the 1992 start of the company. “And we were over budget. The Gibbs organization began to question whether they should even be in racing.”
A year later, Dale Jarrett piloted a JGR car across the finish line in Florida, winning the Daytona 500, and the company has been winning races ever since. Bringle credits the skill of JGR’s engineering team, coupled with advanced technology from sponsors, for the team’s large collection of wins.
Machine tool partnership
In 1998, JGR and machine tool maker Doosan signed a sponsorship that included four horizontal machining centers, 11 vertical machining centers, five turning centers, a 9-axis mill/turn multitasking machine, and a 5-axis vertical machining center. All 22 Doosan machines run two shifts a day.
Brian Levy, design engineer, explains, “We manufacture more than 2,000 different parts, 150,000 total parts per year, which makes up 90% of a finished race car. We simply wouldn’t be where we are today without the Doosan equipment. We don’t have to rely on anyone else, no outsourcing, no waiting on someone to deliver a part. Our advantage is that we make everything here.”
NASCAR rules evolve constantly, creating the dual challenges of staying current on regulations while maintaining a competitive edge, Levy says. “The Doosans are a huge resource that we have,” he adds. “Every time we get a new machine in-house that has a new capability, whether it’s being able to machine more complex geometries or use different types of tooling, we are all over it right away.”
After each race, crew members offer suggestions on how to improve car performances, Levy says. With the newer multifunction Doosan machines, he says there are few limits to what JGR can produce.
Rapid turnaround
“When our race teams come back from the track and suggest they’d like to try a new spindle geometry on this part – which is a little bit different than what we’re running – we can draw it up in 3D, download it to the machines, and have that new part on our desk in two days or less,” Bringle comments. “Being able to turn design concepts or new ideas around in such a short time is really a tremendous advantage.”
Maintaining a large number of internal machines also lets JGR experiment with new techniques and materials. For example, the team is now using titanium in several car parts instead of steel or aluminum. Though more costly, Bringle says the lighter-weight material shaves time on the track.
“We try to get all the extra weight out to achieve our 3,400 lb limit,” Bringle says. “At the end of the year we will take all the parts out of the car, weigh them, and decide which ones need to be redesigned or reworked. One of the goals is to get the center of gravity for the car as low as possible because that helps the performance of the car. We want most of the mass of the car to be as low as possible, so the upper parts of the car must be lighter than the lower parts of the car.”
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NASCAR suspension coiled springs The front and rear springs on race cars are not flat on the bottom. A coiled spring terminates with the end of the tang hanging in space. Joe Gibbs engineering teams have to manufacture a helical spring perch that serves as the mating part for the spring. The team uses its Doosan VC 630/5AX dedicated full 5-axis vertical machining center to simultaneously machine all five surfaces of the part. As the suspension travels, the interaction of the spring and perch greatly impacts the spring rate of the whole suspension system, affecting the behavior of the car. Race engineers will spend weeks and months working with the complex geometries of these two mating parts. Setups change from track to track and driver to driver. Though tracks are all basically ovals, they’re all different – some are longer, some are shorter, and the speeds are different. Some tracks have more banking, some have more bumps, so the load that each wheel experiences changes from track to track, and even from corner to corner within the same track. Machining specific springs and spring purchases for each driver and race allows race engineers to fine tune the relationship between those parts, tailoring how the suspension of the car moves and how the load is distributed on all four corners of the car. |
Pressure to win
Team founder and three-time Super Bowl winning coach of the Washington Redskins Joe Gibbs, known as “Coach” at JGR, says crafting custom parts for every driver and race isn’t easy, but winning rarely is.
“To win in professional sports you have to have people who perform under pressure,” Gibbs states. When asked about his 17-year partnership between Doosan Infracore America, he sums it up as, “I think one of the most important things about Doosan, the machines, they’re great, they’re awesome, they’re the best. But really it’s their people and the way they stand behind you for the life of the machine. We have a great partnership here and you can see the Doosan machines perform under pressure, because we have a race every seven days. It’s great having Doosan as partners, and having them at your back.”
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Steering system drag link
A 9-axis vertical machining center and horizontal turning center, the Puma’s B-axis spindle can articulate 120° in either direction and has a 40-tool automatic tool changer. Work piece capacity is 30" of maximum turning diameter and more than 60" of turning length. “We are able to take a 105 lb blank and machine it down to an 8 lb finished part, and the tolerances are 0.003" from one end to the other,” says design engineer Brian Levy. The old system demanded 15 hours of machining, 18 setups, and 42 hours total setup for the three parts. The Puma still requires about 15 hours of machining, but setup times fall 77% to 9.5 hours. Eliminating welding saves even more time. Levy credits the drag link change for moving racers two to three positions higher in qualifying rounds for races. He continues, “The increased part stiffness improves the responsiveness of the steering system, providing better feedback to the driver’s hands, which allows the driver to take each turn more smoothly.”
Titanium wheel-mount cones During a tire change on pit row, the wheel carrier slides the wheel over a titanium cone attached to the axle assembly. A small cover goes on the end of the housing, and the cone mounts to the housing. “This cone guides the wheel,” says Eric Groen, sponsor services manager and rear tire carrier on the #20 JGR Cup team. “You slide the wheel onto the cone and then drive the lug nuts down. Without this cone, it might add a full second to the tire change.” Joe Gibbs Racing had used steel or aluminum for the cones, but those metals can ding during wheel changes, potentially creating metal-to-metal resistance that could interfere with the smooth mounting of the wheel. Titanium offers longer life and resists dings. Mark Bringle, technical sponsorship and marketing director, explains, “These are a pain to manufacture. With titanium there is no heat transfer to the insert, so you have to cut it really slowly, and you’ve got to flood it with coolant. A blank for one of these titanium cones is $900. And then we have to hollow out the inside with the Woodruff cutter, and this part just eats inserts up. We probably have a full day of machining on a single titanium cone.” Race engineers use five different Doosan turning centers for the slow, precise cuts, some that have been in the shop for as long as 16 years. Bringle says the machines’ box guideways allow superior rigidity, allowing for reliable part creation. |
The drag link connects the power steering box to the spindles in racecar steering systems. Joe Gibbs Racing’s old design required three separate pieces welded together. Using Doosan’s Puma MX2600ST mill/turn multitasking machine, engineers were able to make the part from a single blank, lowering weight, increasing strength, and shortening production time.
Joe Gibbs Racing
www.joegibbsracing.com
Doosan Infracore Machine Tools
www.doosanmachinetoolsusa.com
IMTS 2014 booth #S-8100
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