In 2007, all three Richard Childress Racing (RCR) teams qualified for the Chase for NASCAR’s Nextel Cup. On top of this formidable accomplishment, RCR’s top race car drivers did great: Kevin Harvick won the famous Daytona 500, Jeff Burton won in Texas, and Clint Bowyer won in New Hampshire and finished third overall in the Chase.
RCR addresses some of the hurdles faced in competitive NASCAR racing by applying accurate, reliable, and fast metrology. Dimensional measurement is performed in support of development enhancements that are implemented across the company’s entire race car: engine, chassis, suspension, body, etc. Using touch probe and laser sensor measurement, RCR technicians identify subtle differences in part geometry that separate race winners from the pack.
Instead of taking suppliers’ dimensional quality for granted, CMM inspection is used to verify most engine parts that come to in the engine shop. In chassis/suspension design and fabrication, RCR accurately and efficiently measures a series of NASCAR-mandated and RCR engineering point coordinates using a hand-held touch probe in combination with an optical CMM.
Another essential process improvement concerns the body fabrication shop, which was transformed into a single large-scale metrology-enabled workspace using laser technology. This allows RCR to perform concurrent coordinate measurements, increasing measurement productivity by more than 20 percent.
In the near future, RCR plans to expand its laser scanning capability and begin X-ray and computed tomography (CT) scanning to investigate the internal structure of parts. The net effect of metrology is that it increases measurement uptime and saves valuable engineering time.
NASCAR engine development
On an annual basis, RCR manufactures approximately 650 race car engines. RCR runs concurrent engineering practices throughout the year while spending 38 weeks a year on the road.
A bridge CMM is installed to run accurate serial measurements on engine parts, such as bare engine blocks, connecting rods, valves, and retainers. |
To meet NASCAR specifications and top race performance, RCR evaluates race car engines on dynamometers that provide the performance readings and maintain each engine performance within tight ratings. After each race, these engines are brought back into the shop to trace and evaluate performance differences. Each part within the shop is inspected using various gauges and instruments.
Another important reason to perform detailed measurement is supplier quality verification. RCR does not want to take any risks concerning the quality of supplied parts.
The CMM verifies specifications of supplier parts. |
A bridge CMM is installed to run accurate serial measurements on engine parts, such as bare engine blocks, connecting rods, valves, lash caps, and retainers. The inspection system fulfills the need for better efficiency, higher accuracy, and repeatability, as well as providing numerical input for RCR’s knowledge base on existing engine designs.
Tactile inspection
The use of traditional verification methodologies, such as micrometers and calipers, are extremely time-consuming and limited RCR in the number of parts that could be measured. There simply were not enough man hours to measure every component. In addition, RCR wanted to increase its confidence that supplier parts meet specifications.
An annual production of approximately 650 race car engines calls for accurate repeatable measurement capability. |
Most of the time, the CMM is equipped with a touch probe sensor, offering absolute measurement accuracy of up to a few microns. The working volume of the CMM represents an expandable work envelope that fits small parts as well as large engine parts, all measured with the same top accuracy. The CMM software captures the geometric data and analyzes the data in real time, providing graphic quality assurance and engineering feedback.
A great deal of time is saved by analyzing the acquired measurement data in real time. |
An example of supplier quality verification is the measurement of connecting rods on a 100-percent sampling basis. The purpose of the automatic measurement sequence is verification of critical dimensional features such as roundness, chatter, honing, and hole diameter. For this metrology application, an absolute accuracy between 1.2 and 3 microns is required.
Laser scanning inspection
The system offers the versatility to combine touch probe with laser scanner measurement. Compared to touch probes, a laser scanner acquires thousands of measurement points per second, capturing both geometric features as well as free-form surfaces. As a result, a detailed graphic representation of the entire part geometry is obtained that is then compared with the CAD model of the inspected part. Overall, laser scanning offers simplified measurement and processing setup, and reduced measurement time.
Metris laser scanning technology captures both geometric features as freeform surfaces. |
A Metris laser scanner collects about 20,000 points per second with a spatial resolution up to 20 microns and accuracies better than 10 microns. This is an enabling technology that describes complex free-form surfaces and geometric features in great detail in the shortest possible time. Obtaining the digital equivalent of the entire surface of an inspected component enables RCR to perform detailed analysis off-line and use the data to drive simulation procedures such as virtual CFD analysis. Interactive scanning reports enable the evaluation of the inspected part from any preferred viewpoint, and permit the user to click locations of interest to consult the underlying metrology data. The large number of measurement points provides a higher degree of confidence that forms a solid basis for well-informed decision-making.
Chassis and suspension development
The recent introduction of the Car of Tomorrow (COT) concept represents the biggest change in NASCAR race vehicle regulation in the last 20 years. COT further tightens overall NASCAR race car requirements and forces race teams to rethink their vehicle engineering processes. This basically means that all teams start from scratch with COT when developing next-generation race cars for the new season and servicing them all season long.
In terms of chassis/suspension engineering, geometric inspection and verification play key roles throughout the entire development process. Therefore, RCR uses a hand-held touch probe unit in combination with an optical CMM. This metrology system enables a reduction in time spent for routine measurement and frees up engineering time.
Optimizing chassis/suspension within NASCAR limitations helps separate winners from the pack. |
When verifying NASCAR-mandated body and suspension points, the hand-held device assists in efficiently acquiring high-precision geometric data. Beyond NASCAR certification, RCR uses the same equipment to acquire RCR-determined critical performance points to engineer as much competitive edge as possible in getting a potential winner to the starting grid. To set up the system, RCR positions the optical CMM next to the vehicle and immediately starts measuring using the hand-held probe unit.
The optical CMM applies triangulation to accurately track the tip position of the touch probe unit. |
The linear CCD cameras built into the system’s optical CMM module apply triangulation to accurately track the tip position of the probe unit. Among NASCAR-mandated chassis characteristics are tube thickness, tube location, and tube geometry. For the suspension section, NASCAR-specific verification testing focuses on upper/lower control arms and spindle drop/offset values in addition to camber, toe and other suspension-specific characteristics.
As the working volume of the metrology system easily fits an entire RCR chassis, it allows RCR to measure point positions using a single coordinate system, eliminating leap-frogging altogether. Where final verification of an entire chassis assembly previously took almost an entire day, a single RCR engineer now completes the same metrology job more than 20-percent faster.
In the past, RCR performed this kind of measurement using a setup with an articulated arm. The limited reach of the arm required multiple setup positions around the vehicle, which in many cases kept two operators busy and ultimately delivered inaccurate and/or inconsistent data due to potential misalignment.
The optical CMM with touch probe allows complete chassis/suspension verification to be completed more than 20 percent faster. |
Although tight regulation applies to most parts of the vehicle chassis, the suspension system represents a relatively unrestricted zone that leaves plenty of opportunity to engineer inherently faster race cars. After establishing subtle compromises between vehicle aerodynamics and handling performance, detailed suspension design and tuning begins.
Consistent tire patch contact with the track can be maintained under all racing circumstances by adapting suspension characteristics to align the driving behavior of the car to the size and banking of the oval track. Besides focusing on designing for lighter vehicle weight, RCR modifies the suspension design, all within the design boundaries imposed by NASCAR. RCR tunes caster and camber along with toe, and designs the right amount of toe out that can be gained on the inside tire in a corner. Following this strategy to bring more engineering in-house, RCR takes full control over chassis/suspension engineering and safeguards its technical expertise.
The suspension system area leaves plenty of opportunity to engineer inherently faster race cars. |
Lessons learned from acquiring more in-depth engineering information support RCR in developing chassis design innovations that step up race chassis performance. In the limited time frame between races and in the off-season, accurate and repeatable metrology helps quickly narrow down technical options and make the right engineering choices.
Accurate, consistent and repeatable data ultimately makes RCR’s yearly production of 40 to 50 chassis/suspension builds truly identical. This is essential in building the capability to compare engineering information, irrespective of the chassis/suspension unit being considered. RCR inserts all acquired 3-D measurement information into its companywide engineering knowledge base, to strengthen the ability to understand the complex physics that are involved in top-level NASCAR racing.
Premium metrology solutions are seen by RCR more as engineering aids than measurement equipment. In this regard, RCR recently extended it measurement system with a laser line scanner, a powerful noncontact metrology solution. Similarly to the hand-held touch probe unit, the scanner is tracked by the optical CMM. As such, the scanner solution allows complete detailed geometric scans of small to large vehicle body parts to be captured in record time.
Scanning at a rate of multiple thousands points per second creates a detailed digital -3D copy of the scanned surface, which easily adds up to millions of measurement points. RCR uses the laser scanner to reverse-engineer chassis/suspension to quickly create virtual FEA and CFD component and assembly models. These digital models are leveraged to run simulations in different engineering fields, including dynamic motion, durability, and aerodynamics.
Vehicle body development
Vehicle body engineering of NASCAR race cars places a greater emphasis on aerodynamics than on structural performance. As the structural cage forms an integral part of the vehicle chassis, RCR crafts the body mainly from sheet metal panels that are cut, curved, and welded together. Despite tighter NASCAR specifications imposed on RCR build teams, finding the optimum balance between body aerodynamics and vehicle handling is essential in achieving faster lap times. As RCR deems critical for aerodynamic excellence, every single RCR race car undergoes extensive aerodynamic performance testing in wind tunnel and on tracks.
To stretch the limits of body engineering and manufacturing, RCR literally turned its entire body fabrication workplace into a precise measurement area. The so-called iGPS system mimics GPS functionality to a large extent. Instead of satellites orbiting in space, the system consists of a number of laser transmitters mounted inside the RCR fabrication shop. Inside the metrology-enabled facility, dimensional information is collected on the spot using dedicated rugged touch probes with iGPS receivers.
Multiple users taking advantage from a single constellation of transmitters provide quick return on investment. |
As the number of simultaneous users is theoretically unrestricted, several RCR race teams use the facility and equipment at the same time. Multiple users taking advantage of a single constellation of transmitters provides a quick return on investment. With this solution, RCR firmly increased body fabrication throughput, while parallel activities eliminated the need for large capital investment in multiple alternative metrology solutions. The system enabled the achievement of a perfect body-to-chassis alignment, guaranteed NASCAR body compliance, and tuned local body shape for optimized body aerodynamics.
Each iGPS transmitter continuously outputs two fan laser beams and a strobe signal. Being pointed on a hood corner or A-pillar point on a race car body, for example, a receiver touch probe can autonomously decode information concerning its own position within the facility. Calculating azimuth and elevation using information received from multiple transmitters enables the system to accurately reconstruct the probe’s x, y, and z coordinates with up to 90-microns accuracy. To extend the metrology-enabled area to the size of the entire body fabrication facility, RCR opted for a setup with 10 transmitters.
This setup additionally offered increased dimensional accuracy and probe visibility because probe positions are systematically referenced to more than two transmitters.
The transmitters mounted on yellow pillars (e.g., left and far right) activate a factorywide metrology workspace. |
Each team is responsible for building 20+ race cars per season and must be able to develop and fine-tune body designs to create confidence that the build is repeatable and meets NASCAR-defined standards. For each vehicle body, verification of over 130 points distributed across the entire body is typical. Besides NASCAR-mandated points, RCR routinely measure a number of critical RCR-determined points that support engineering and optimizing aerodynamic performance.
Traditionally, body measurements relied on surface plate setups and rudimentary tools, such as levels, plumb bobs, and tape measurements. It took a half day and seasoned measuring specialists to successfully complete dimensional verification of a single race car body. Today, one engineer performs sequential verification of all 100-150 measurement points in just an hour.
Acquiring more accurate information helps tune local body geometry for improved down-force drag and better overall aerodynamics. |
As opposed to unidirectional manual measurement that is very time-consuming, the metrology system promptly spots x, y, and z positional coordinates and saves the data. To avoid template errors, it systematically identifies absolute point coordinates that are referenced to a single coordinate system. This kind of data consistency makes the system quite a unique metrology solution. It is used for intermediate measurements when building the body as well as for final body tuning and verification. The system transformed body fabrication metrology into a highly reliable and entirely digital process that supports faster and more detailed aerodynamics engineering. Acquiring more accurate information helps RCR tune local body geometry for improved down-force drag and better overall aerodynamics.
RCR has taken a more proactive approach with better accuracy and efficiency in addition to a significantly larger work volume. The acquired geometric data automatically populates numerical reports that support technical decision-making, and drives graphical reports showing body shape overlay between race vehicles. The ability to quickly capture the geometric body signature of race vehicles provides the necessary engineering depth to flexibly enhance body design from race to race. Radical improvement of measurement quality, speed, and consistency help in the development of the superior aerodynamics of true race winners.
Future developments
To further develop our metrology capability that supports faster and more in-depth race car development and fabrication practices, RCR is currently looking into two new emerging metrology technologies: iSpace and X-ray/CT scanning.
iSpace technology
The so-called iSpace metrology technology combines multiple existing technologies, creating a versatile metrology-enabled workspace between 400 and 1,200 square meters. Within this metrology area, RCR will be able to take measurements using hand-held touch probe units, articulated measuring arms, and, eventually, even laser radars. The innovative network concept of this large-scale metrology solution will provide a uniform accuracy throughout the entire workspace. It will serve multiple concurrent users, who will be able to measure and track multiple objects simultaneously.
The measurement devices can be repositioned at any time without having to manually redefine their new locations each time they are moved. By eliminating these interruptions altogether, RCR will be able to run measurements nonstop anywhere needed within the entire metrology workspace, resulting in faster turnaround times. iSpace technology allows the tracking of parts, tools, part joining, and assembly.
Within the metrology-enabled workspace area, we will be able to take measurements using hand-held touch probe units, articulated measuring arms and eventually even laser radars. |
X-ray/CT scanning
X-ray technology will open up a broad spectrum of inspection applications. Where touch sensor and laser scanning digitize the outer geometry of test specimens, X-ray provides an accurate view on the internal structure of components, in an entirely nondestructive fashion. Based on a large number of X-ray images, computed tomography (CT) reconstructs an interactive 3-D scene, which is able to be navigated to verify internal details.
X-ray technology is well-accepted for nondestructive testing and visual inspection of safety-critical components. More recently, computed tomography quickly gained interest for detailed visual inspection and metrology applications. The advantage of having a digital representation of the test article—full 3-D or surfaces only—is that it can execute inspection off-line and fully automatically. Automated inspection will not only save time, but also yield operator-independent results. In addition, it can be adapted to an inspection strategy at any time, without having to re-measure the part. By separating digitizing from inspection, RCR can have data collection performed by nonmetrology experts.
X-ray image of the internal structure of a carbon fiber part. |
Major breakthroughs in manufacturing capabilities are generally preceded by major breakthroughs in metrology. RCR’s metrology solutions brought dimensional accuracy and manufacturing consistency that clearly exceeds NASCAR Car of Tomorrow certification requirements. More importantly, they help lay bare the root causes of race car limitations, which creates that extra competitive advantage that separates winners from the pack.
The authors would like to gratefully acknowledge Nick Hayes, RCR engine R&D responsible; Chris Hussey, RCR director of engineering; Ronnie Hoover, RCR fabrication facility responsible; Bobby Hutchens, RCR vice president of competition; and Jim Clark of Metris USA.
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