Edited by Michelle Jacobson
Machinists at Richard Childress Racing use a 9-axis Okuma Multus 4000 mill-turn machine to create parts for racecars. As the race team has added machining capability, the need to simulate the process has grown.

Richard Childress Racing (RCR), an elite NASCAR organization founded in 1969, fields three teams in the NASCAR Monster Cup Series and five teams in the NASCAR XFINITY Series. It has accumulated more than 200 victories and 17 championships across NASCAR’s top series, including two Daytona 500 wins and three Brickyard 400 victories.

Achieving that kind of success demands a team of hundreds of skilled people: drivers, crews, management, clerical workers, and manufacturing personnel.

When the car doesn’t succeed in competition, RCR Manufacturing Manager Rocky Helms says, “You don’t want someone to say, ‘Well, we ordered a part that probably would have made us run faster, but the manufacturing department didn’t get it done in time. It’s your fault we didn’t run faster.’”

After a car is built, the team’s machine shop constantly modifies and improves components. Team engineers and track personnel devise performance-improving upgrades, or find weaknesses that can be remedied with a new part geometry.

“A part that makes you a half-a-second faster each lap can be the difference between winning the race or finishing 20th,” Helms says. “It might take updates of 10 different parts to gain two-or-three tenths of a second on the track.”

Intense competition has driven race teams to assemble sophisticated in-house CNC machining operations to produce increasingly complex parts, maximize control over the processes, and quickly update parts.

“Every machine tool, every day, is running a part that usually has to go to the race track or to a test in the next couple of days,” Helms says. “Machine utilization is important for any manufacturer, but every part we make is needed the next day or sometimes the same day.”

Spring Technologies’ NCSIMUL software simulates machining on the Okuma mill-turn machine.

Simulation challenges

RCR’s team uses CNC machining simulation software to speed machining output by revealing programming errors before they cause delays on the shop floor. It initially employed a simulation program that was embedded in the shop’s computer-aided design/computer-aided manufacturing (CAD/CAM) package. Using cut-line data, the simulator validated the CNC cutting program, sent it through a post-processor program, and translated it to G-code. However, the G-code sometimes produced unexpected machine motion or other errors, problems not apparent until the code got to the machine.

When operators edited defective G-code at the machine, they couldn’t simulate and test the result because the shop’s simulation program didn’t analyze G-code. In addition, the simulation package did not cover a machine’s full range of motion, fixturing, or components; and simulated tool holders did not match those in use.

Richard Childress Racing Manufacturing Manager Rocky Helms says software simulations of machining processes have accelerated how quickly his team can produce custom parts for NASCAR races.

“You would spend at least one to two hours after you had posted doing editing and then make sure you had everything corrected the best you could,” Helms says.

To minimize the time lost waiting for program corrections, RCR invested in Spring Technologies’ NCSIMUL, a machine simulation software package that analyzes CAM programs and indicates errors so they can be corrected before the postprocessor generates G-code. The software also examines the G-code to determine how the program performs in relation to the part, the machine setup, and the machine components. Errors are flagged so users can correct the code and eliminate potential crashes. The software compares the simulated part geometry to the original CAD model, based on the toolpaths, and a kinematic model of the machine tool involved.

Helms says simulation has become more important as part modifications have evolved from purely structural changes to include aerodynamic factors.

“Our part geometries have become way more complex in the last two to three years. Everything on the car has become aero-dependent,” Helms says. “We’re starting to look at the underside of the car for aerodynamic advantages. Many chassis components previously were designed purely to meet structural or geometric needs, but now they also are modified based on how air flows around them.”

Maximizing airflow

Engineers attach sheet metal and other materials to cars in wind tunnels and use computational fluid dynamics (CFD) software analysis to find changes that make the car faster. When an experimental part produces an improvement, the engineers make a 3D CAD model of it and Helms’ shop machines it. RCR uses 3D printers to make non-structural prototype parts that, if successful, can be machined in steel, aluminum, or titanium for racing.

Free-form contours of aerodynamic parts require complex 3D surfacing machining programs. To support those complex designs, RCR added a 9-axis Okuma Multus 4000 mill-turn machine. The machine tool has an upper milling head that can rotate 240° and a bottom turret with tools for turning. The machine can transfer parts from main spindle to sub-spindle and perform simultaneous machining on both spindles.

“None of the programmers are familiar with this type of machine, so it’s a lot better to simulate the process through NCSIMUL instead of getting it to the machine and implementing it in a piece of material,” Helms says. “With the software, the programmer can see errors on the monitor and correct them, versus having an operator crash a $750,000 machine.”

Ryan Newman drives the Richard Childress Racing 31 car at the Toyota Owners 400 in Richmond, Virginia, in April 2017, placing 7th in the race.

He adds that the complexity of aerodynamically optimized parts, coupled with the machine’s sophistication and part programming options, demand simulation.

“When you get into surfacing, it’s easy to make a small programming mistake and not notice it until you’re holding the part in your hand. The NCSIMUL representation can be compared to your (CAD) model to make sure you got everything right,” Helms explains.

Helms has seen massive growth in NASCAR competition. Intensifying competitiveness has prompted RCR manufacturing operations to grow from two machines and two operators to 18 machines and a staff of 22 that works two shifts. Amid that fast-moving environment, NCSIMUL simulation software is helping RCR meet competitive challenges and continue its success.

“When I got into racing 23 years ago, there were 10 competitor cars that legitimately could win a race,” Helms says. “Now, any of the top 25 to 30 cars could win.”

Okuma America Corp.

www.okuma.com/americas

Spring Technologies

www.ncsimul.com