Shops Upgrade Drag-Racer Production
Many racing teams and some suppliers of parts are making the move to advanced CNC fabricating equipment
By Bruce Morey
A dragster is a collection of metal, rubber, and composite parts assembled into a vehicle designed to go a single quarter mile or less. Exciting to watch, that short trip tests these machines to their design limits. Whether the vehicles are 8000-hp (5976-kW) Top Fuel rail cars or street-legal hobby machines, teams constantly search for a technical edge while finding ways to make the vehicles safer. This effort translates into low-volume production runs and an approach to building parts and vehicles that resembles the work of an artisan. Transitioning to advanced CNC equipment from machinery operated by a machinist is seen as a clear advantage for some.
Finding the edge usually starts with prototype parts. "We convert an idea into a part," explains Dan Drinan, president of Drinan Racing Products (Indianapolis, IN). "For dragsters, we typically build parts that direct airflow under the body to create down force in the back of the vehicle, loading the rear tires. Our parts are often used in wind-tunnel testing." Many of his prototype parts end up as composite components after full testing in metal. His shop boasts a variety of hand-controlled power equipment for milling and cutting, and processes metals such as titanium, Inconel, and 4340 chromiummolybdenum stainless. Drinan and his associates final-machine parts from near-net-shape workpieces such as prebent tubing or castings.
Like a lot of racing shops, Drinan Racing Products values expertise over equipment. Dan Drinan notes that higher-end CNC machinery is not an advantage for him, at least at present. "In a few instances, we have taken an idea to production, but in most cases the parts are oneoffs." Because they are unique components, he believes that the effort required to program a part for a CNC machine is not economical, at least at present, though his shop uses CAD extensively for designing parts. This attitude, though prevalent—even representative of the field—may be changing.
One manufacturer that values expertise highly, yet believes in advancing its equipment inventory, is Steve Schmidt Racing Engines (Indianapolis, IN), a builder of custom drag-racing engines. Steve's shop produces over 600 such engines per year. Their engines are primarily aimed at the sportsman classes (see Drag Racing in a Nutshell).
To make these engines, they gather purchased parts that are near-net-shape, and then do finish machining. In some cases, they coat the workpieces with a PVD-like coating to achieve the high performance race engines require. Their sportsman-class engines push the envelope, some spinning over 10,000 rpm and generating up to 1540 hp (1150 kW). The tolerances they must meet are exacting. "Cylinder bores need to be within 0.0001" [0.003 mm], valve face heights to ±0.001" [0.03 mm] on assembly," explains Schmidt. To meet these requirements, he uses a mix of commercially purchased equipment with custom jigs and fixtures, special-purpose honing equipment.and experienced shop personnel. "It all comes down to the fellow doing it," says Schmidt. "For instance, the guy who hones our blocks [with a Sunnen CV-616] has been honing for 30 years."
Nevertheless, Steve Schmidt Racing Engines is beginning to augment its operations with a new five-axis CNC machining center. "While I still need the expertise from my professionals to build quality racing engines, the CNC machine makes cylinder heads in two days, and it used to take two weeks," explains Schmidt. "I need that productivity." He also notes that not all parts, since they are low-volume, would warrant the programming time to make the CNC worthwhile.
What better proving ground for testing your parts than sponsoring your own Top Fuel professional racer. That's what Bill Miller Engineering (BME; Carson City, NV) does to ensure that its line of superchargers, pistons, wrist pins, and connecting rods meet the needs of the entire racing community. "Our race team is our test bed for our parts," says Bill Miller, company president. By concentrating on a limited set of components, BME in some ways enjoys the economies of a production house, while providing a custom-engineered product to its customers.
Perhaps because of this mix, BME has embraced the use of state-of-the art CNC machines. "Our drag-racing pistons, made from 2618-T651 aluminum, are less complex to build than NASCAR pistons, but still require 25.30 separate machining operations from a near-netshape forging," explains Miller. They produce about 850 pistons per week, and each month around 1000 aluminum connecting rods and 1000 wrist pins. Surface finish roughness of ring grooves are typically less than 1.5µin. (38 µm) roughness average (Ra). Flatness in 360° is about 0.0001" rise-and-fall around the perimeter. "In truth, tolerances and accuracy are what I want them to be," says Miller. "Our operations may be more laborintensive than others, but we can afford it because our customers absolutely need that edge. Power is everything in this game. Spending more to deliver an extra 1/2 hp (0.37 kW) per cylinder could translate to 0.01 sec difference in a professional-class dragster. That is decisive."
They machine their pistons on two Okuma LU 300-V8 CAM turning lathes and their magnesium supercharger on an Okuma MU-400VA five-axis VMC. "These newer CNC machines have allowed us to improve production by 30% over the last two years," says Miller. CAM programs used to produce G-code machine instructions include VirtualGibbs, SmartCAM, and MasterCAM. "CNC programming has improved by leaps and bounds from when we first started using machines like these," says Miller. While delighted with his current generation of CNC machines and impressed by current improvements in programming, even simpler and more powerful programming tops his list of sought-after improvements.
Xceldyne Technologies (Thomasville, NC), has fully embraced CNC manufacturing for their valve train and other engine components. "Our focus is aimed at the top end of the market, for all forms of professional racing," says Scott Highland, general manager. "Drag-racing requirements are quite comparable with other forms of racing from our perspective. As an example of how we are pushing the limits, not only do we make our valve stems from titanium, we gun-drill the stems to remove even more mass." Not content with that, Xceldyne developed a proprietary methodology to bond two unique sections together to form a hollow cavity in the valve's head region, for even greater mass reduction. Coatings used to reduce wear and improve sealing include thermal spray and HVOF technology, and thin film coatings such as TiAlN, DLC, TiN, and CrN.
Operating more than 55 CNC machine tools, some capable of holding micron-level tolerances, Xceldyne also uses numerous optical and laser-scanning systems, CMMs, roundness gaging, profilometer, surface-finish, microhardness, hardness, and other QC instruments for optimal tolerance testing. An Objet Eden 333 rapid prototyper produces plastic parts used to evaluate designs before machining metal prototypes or moving them into production. Low-production runs do not seem to hinder their use of advanced equipment. "Production runs are typically from 25 pieces to the hundreds," says Highland.
Noting that sportsman and amateur-class racers are just as concerned with value as performance, Xceldyne is running a support vehicle at NHRA-sponsored races to better understand such racers, who must balance innovation, reliability, and quality with value.
Like engines and components, the chassis of each professional-class (and many a sportsman-class) drag racer is also a hybrid—a standard product that is customized for each product. "This market is constantly changing. What we use six months from now may not be what we are using today," says Murf McKinney, president of McKinney Corp. (Lafayette, IN), provider of a substantial portion of the chassis used by Top Fuel and Funny Car racers. "We are constantly finding ways to improve both safety and performance." One solution to this unique blend of job-shop and production requirements is to produce small batches of parts and components in a just-in-time operation. If this sounds like Lean Manufacturing based on the Toyota Production System, it should. "We tried to adopt the best of TPS and lean. We proved that lean works for us. Smaller batches reduced cycle times and inventory, AND solved a back-order problem we had prior to adopting lean."
Still, the low-volume business has its disadvantages. "Our line does not move, and that makes controlling productive labor hours a real challenge. Each product is still hand-crafted to a degree. Although we sell standard products, in some ways we are a job shop on-demand."
The space-frame construction of each chassis is made from standard 4120 chromium-molybdenum steel tubing. The tubing is bent, laser-cut, assembled with fishmouth matings, and welded. Tolerances range from 0.0625" (0.47 mm) in the chassis frame to 0.020" (5.1 mm) in the rear end. A specially designed modular fixture "controls the core," while being flexible enough to adapt to changes from the last design iteration. A Faro portable CMM equipped with a touch probe provides the quality control check for all parts and chassis. McKinney Corp. also has its own tensile tester. Two pieces from each length of tubing they purchase undergo destructive testing to ensure that modulus of elasticity, yield strength, and tensile strength are as expected.
While expressing general satisfaction with his equipment, he does offer some thoughts for makers seeking to meet the demands of race shops like his. "We have limited runs of 10–25 parts before we re-engineer them," says McKinney, which means they never get to build parts as efficiently as production houses that produce long runs. Therefore, the three things he looks for in evaluating new CNC machining equipment are: 1) minimal setup time, 2) making parts first-time-good-part, and 3) minimizing changeover to the next part. "In a shop like ours, I honestly don't care about cycle time," says McKinney.
Although the move to more-advanced, computer-controlled machining equipment might be daunting for first-time users, there are companies like RMC Engine Rebuilding Equipment Inc. (Saginaw, MI) who specialize in making that transition easier. They concentrate on integrating complete machining cells. "Our typical customer wants to do a small-block Chevrolet or a cast Ford 460 block with a low deck," says Matt Meyer, RMC's general manager. "We provide the CNC machine, the workholding, jigs, fixtures, specialty toolholders, CAM programming, and training. Starting from a blueprint or CAD file of what they want, we build a complete system. Three days after delivery they should be cutting their product." Acting as consultants, RMC also helps customers develop original CAM programming as new situations arise.
Noting that tolerances and quality are far more important than throughput, RMC provides the extras the user needs. While specializing in fixtures built to exacting tolerances, they also provide in-machine measurement equipment to ensure accuracy. "Each of our CNC machines is almost a CMM as well," says Meyer. "The probe.in some instances.automatically provides G-code offsets to control tolerances." Meyer notes that the prices of CNC machines have dropped over the last eight years, making such equipment more attractive for short-run production of drag-racing parts.
A company that recently acquired one of RMC's machining centers is Gressman Powersports (Fremont, OH). "I shopped around for two years before I selected RMC. The fully integrated package was priceless once we understood what we could do with it," says the company's President, Scott Gressman, after purchasing an integrated system built around an RMC V40 four-axis machine.
He notes that many people in the racing-components industry are reluctant to use such advanced machining, citing fears about cost and the investment in time required to learn how to program the machine correctly. "Only a select few racing-components manufacturers use CNC," he says. The advantages for him far outweigh concerns. "In one instance, what used to take 20 hr on four separate 'hand-operated' machines now is done in 3 hr on the CNC. And quality is better, eliminating tolerance stack-up with a single setup," says Gressman. He's extending the use of his equipment beyond the original application that RMC provided, profiling crankshafts. Gressman observes that easier programming would make it even more valuable. "For us, the difficulty is the parts programming. It prevents us from using CNC even more."
Despite what might be low penetration in the racing market, at least one CNC supplier is looking at an upward trend. "We are seeing more CNC machinery go into racing shops as these guys look to control more of their own destiny," says Bob Kral, vice president of operations at Okuma America Corp. (Charlotte, NC). "I've seen a prominent NASCAR team run a CNC machining center attached to bar feeders and parts accumulators basically untended. Besides productivity, CNC offers—even for low-volume parts—the ability to capture what they have done and not rely so much on a specialized, highly skilled machinist." He believes a generation that grew up with computers is easing the acceptance of computerized CNC machining operations. "Computers don't scare people anymore. The computer is becoming a familiar tool." He points to Okuma's open-architecture Thinc-OSP controller, which is PC-based and runs on a Microsoft Windows operating platform. Besides running the machine tool, it runs any desktop program such as word processing or SPC packages, and can be networked to provide Internet access or even to allow communication between the machine tool and business systems.
Kral believes Okuma offers what racing shops are looking for.off-the-shelf accuracy, an open architecture controller, and a total integrated package of equipment and software. "We can offer one-stop shopping for those who want it." Backing up this claim, he points to over 30 partners in their Partners-in-Thinc facility who can bring expertise to a project. "All the things that the big manufacturers are doing we are attempting to help the smaller race suppliers do."
Drag Racing in a Nutshell
In US racing, the National Hot Rod Association (NHRA) is second only to NASCAR for size. With over 80,000 members and 35,000 licensed competitors, its diversity is demonstrated by its more than 200 classes of drag racers. There are four top professional classes—Top Fuel, Funny Car, Pro Stock, and Pro Stock Motorcycle. Professional-class racers command substantial prize money and big-name sponsors. Top Fuel dragsters typically eat up the quarter-mile in 4.5 sec at more than 325 mph (523 km/hr). The other 196 racing classes, known as sportsman classes, include vehicles built and driven by enthusiasts who buy a respectable amount of racing equipment. Many race tracks used for sportsman-class racing are 1/8 mile (0.2-km) long rather than the professional quarter-mile (0.4 km). While claiming some prize money and endorsements, most of these racers are in it for fun as much as profit. The big news may be that drag racing isn't only an American sport anymore. Some suppliers are seeing double-digit growth coming from other countries, such as Sweden, Finland, Norway, Venezuela, Australia, and New Zealand.
This article was first published in the September 2008 edition of Manufacturing Engineering magazine.
Published Date : 9/1/2008