Shop Solutions: Riding an Abrasive Waterjet to Victory
After thousands of hours of preparation in shops and training on tracks, motorsports teams achieve victory and racing success in a series of moments measured in a hundredth of a second here, a thousandth of a second there.
Put them end to end and they add up to a few brief seconds that are often enough to snatch a place in Nascar history as a winner in the season-long Chase for the Sprint Cup.
Few teams in Nascar stock car racing have experienced that success more often than Richard Childress Racing (RCR; Welcome, NC). Founded by the namesake, a former Nascar driver, in 1969, RCR was built on the foundation of Dale Earnhardt's legendary career. The storied franchise has amassed more than 180 victories and 12 Nascar championships. RCR was the first Nascar organization to win championships in all three of Nascar's major touring series: the Sprint Cup Series, Nationwide Series, and Camping World Truck Series.
After Earnhardt's untimely death in 2001, RCR endured a five-year roller coaster ride that saw it drop from the ranks of Nascar's elite. In 2006, a new era of success was ushered in when Jeff Burton won the pole position for the Daytona 500 and proceeded to break a four-year winless streak. RCR's Kevin Harvick emerged as a consistent top-ten threat in Nascar's top series.
Also in 2006, Rick Grimes, manufacturing manager at the RCR/Okuma Technology Center (RCR/OTC), began investigating the potential of abrasive waterjet machining, as a versatile cutting solution to meet the shop's requirements for short-run machined parts.
"We saw abrasive waterjet as an ideal solution for rapid prototyping, part production, and just-in-time manufacturing," says Grimes. "We needed a robust performer that could help increase flexibility and, most importantly, improve turnaround time. After meeting representatives from Omax [Kent, WA] at IMTS 2006, I knew their product would provide a significant boost to our engineering and machining processes."
In November 2007, Omax delivered a 55100 JetMachining Center to RCR. The 55100 is one of the largerfootprint JetMachining Centers, designed for machining large complex parts from sheets of material ranging from aluminum and rubber to wood and Plexiglas, instead of bar stock.
The abrasive waterjet is equipped with Omax's Tilt-A-Jet system for achieving zero taper. When the system is in use, software automatically calculates and offsets the natural taper that results from the abrasive jet stream. The taper is moved from the part to the scrap, leaving parts with perfectly square edges.
"The outstanding accuracy and taper-elimination capabilities really sold us on the machine," notes Grimes. "Additionally, the waterjet could provide clean edges without creating a heat-affected zone, which improved our ability to weld machined pieces."
The JetMachining Center was the second piece of equipment moved into the new RCR/Okuma Technology Center (RCR/OTC), a 17,000-ft2 (1579-m2) facility where all precision-engineered components are manufactured for the nineteen departments within RCR. Omax provided installation support and operator training, and within a week of delivery the machine was up and running.
"The waterjet is a user-friendly system that is not complicated to program or operate," says Grimes. "Omax trained Eric Drinkuth, an RCR CNC machinist, on the system. He, in turn, trained fellow machinist, Bobby Myers, which improved staff flexibility. Our machinists also learned how to perform pump rebuilds and other maintenance requirements without outside assistance."
Once word of the shop's waterjet capabilities spread through RCR's 500,000-ft2 (46,451 m2) campus, the floodgates opened, and the 55100 began machining parts ranging from one-off, simple 2-D prototypes to multiple-piece complex shapes that are sometimes completed on RCR/OTC's Okuma and Sodick machines. Improvements in flexibility, productivity, and rapid prototyping soon required RCR/OTC machinists to fabricate parts not only for Sprint Cup and Nationwide race cars, but also for internal support organizations like the chassis and fabrication shops and engineering and suspension rooms.
"The body-fabrication shop asked us to machine two pieces of butcher-block tabletop that would be used to form the inner rail for the wheel wells on the car," Grimes recalls. "We put a chunk of wood on the 55100 and cut the profile along with a few lightening holes. This level of versatility would not have been possible without the waterjet."
For materials exceeding 1/8" (3.2-mm) thickness, the JetMachining Center not only saves $2–$4 per part for RCR, but also reduces the total machining time of certain processes when used in concert with the shop's Okuma and Sodick machines. One of the most successful productivity improvements has been in the manufacture of the throttle return-spring bracket, an aluminum part that bolts directly to the intake manifold.
"Prior to the 55100, it took a little more than 5 min to cut the brackets on the machining centers," says Grimes. "By using the waterjet to blank the part profile, we were able to cut that time to 2 min, 42 sec for a 52% reduction in total machining time."
The RCR/Okuma Technology Center is also inundated with prototyping requests, as well as orders to manufacture parts previously outsourced to third-party vendors. Having eliminated the need to outsource laser projects, the waterjet has helped RCR/OTC produce more than 300 different part numbers—a figure that grows by the day.
"In the 2007 season, we manufactured 28,000 parts for our customers," notes Grimes. "We improved our output to 52,000 pieces in the 2008 season. Nearly 12,000 of those parts were the direct result of having the Omax JetMachining Center in the shop."
A new part in production is an aluminum piece that mounts small bottles for fire-extinguisher systems. In the past, the part would have required three operations on a machining center, but with the 55100, the part can be fabricated in two operations. The fire-bottle mount also represents a philosophy change for manufacturing processes at RCR. Lacking the shiny finish that defines CNC machining, the part could be perceived as low quality, but it is far from that.
Currently, RCR/OTC uses a oneshift operation. Though the waterjet runs no less than 8 hr a day, five days per week, and produces lot sizes averaging 1–100 pieces, the machine still faces a two-to-three-week backlog on parts in the busiest times of the season. However, Grimes is quick to note that the heavy volumes do not prevent his team from interrupting operations for prototyping. The JetMachining Center's ability to cut a few prototypes and return to the interrupted spot on the cutting path during long runs makes it the preferred tool for RCR when time is of the essence.
Once informed that a newly designed part needed to be fabricated in time for a race on the upcoming weekend, RCR/OTC machinists were able to take the piece from design to conception in less than 1 1/2 business days. The following Saturday night, Kevin Harvick earned a narrow victory over Kyle Busch at the Chevy Rock & Roll 400 at Richmond International Speedway. The win was Harvick's third of the season, and clinched his first berth in the Chase for the Nascar Sprint Cup.
"The biggest advantage to having the JetMachining Center is the turnaround time," remarks Grimes. "We are week-to-week. The haulers return on Sunday and leave on Wednesday or Thursday to hit another racetrack. Having the ability to take CAD drawings or .DXF files and have a part in hand in a matter of minutes is crucial to our success in this sport."
Since implementing the waterjet in late 2007, RCR's Sprint Cup teams have won three races and amassed 25 top-five and 58 top-ten finishes. The 2009 season looks even more promising for the franchise, which began with a victory in Daytona at the Budweiser Shootout All Star Race for Kevin Harvick and the No. 29 Shell- Pennzoil Chevrolet Impala SS.
"If you can control your quality and your lead time, you can control your destiny," says Grimes. "That is what this is all about. The flexibility, speed, and versatility that Richard Childress Racing has gained from incorporating an Omax JetMachining Center into our manufacturing process has helped put us in a position to not only compete every weekend but also return to our rightful place as one of NASCAR's elite organizations."
Robot Clears a Mountain Bottleneck
The town of Erwin is just a two-mile (3.2-km) hike off the Appalachian Trail where East Tennessee borders North Carolina. Native Americans once used this area, like so many communities in these mountains, as a hunting ground. Even today, Erwin residents regularly uncover arrowheads or other treasures in their gardens.
"We've been making motors in the heart of this 640,000-acre [258,999-hectare] Cherokee National Forest since the mid 1960s," says Shannon Vaughn, plant manager for Morrill Motors. "We understand that a good work environment and quality of life are very important to the people here."
Morrill Motors is a leading employer in the area and the manufacturer of long life, 1–25-W unit-bearing motors used in a wide variety of industrial, commercial, and residential product applications. They can be found in everything from supermarket display cases and beer coolers to commercial ice machines and beverage dispensers.
The company traces its roots back to founder Wayne J. Morrill, who had attracted a great deal of attention in the 1920s as an undergraduate electrical engineering student at Purdue University when he contributed to the design of the first computer capable of complex computations. He later published a paper defining the design and performance of single-phase electric motors. His theory was so advanced it is referred to as a "classic." It is still being taught in universities, and has been adapted to modern computer processes.
As an innovator at General Electric in the 1940s, Morrill led the design of the first unit-bearing motor to meet the need of long-life fan motors. After opening Morrill Motors in Indiana in 1946, he developed a new type of portable generator for use in the field by the armed forces.
Morrill's core competencies were expanded and its technological leadership continued under Paul Farnor and Jim Mitchell, who purchased the firm in 1998. They soon merged Morrill Motors with both R. M. Engineering, a machine shop with full tool and die capabilities, and A. B. Plastics, a custom plastics-injection-molding facility. Growing again in 2003, Morrill Motors formed a joint venture in China: Morrill Global Motors. In 2007, Morrill became a part of parent company Regal Beloit Corp. By then, Morrill was serving customers around the world, shipping to Germany, Sweden, United Kingdom, Mexico, New Zealand, Australia, China, and South America.
For all its expertise in product performance, Morrill Motor's Erwin plant was encountering problems in keeping its production line performing at peak efficiency. A human operator would first load a motor housing onto the mandrel on an Acme multispindle machine, then remove the part after the front side was machined. Another operator would load it on a Borematic single-spindle machine to finish the back side. This created productivity challenges that were tailor-made for a robotics solution.
Vaughn remembers that the company was challenged by all kinds of problems. "Inconsistent loading styles from shift to shift slowed production," he says. "Sometimes the hand-loaded part was not oriented correctly. Much of the time, 4000. 5000 parts were tied up in the bottlenecked line. Productivity was flat."
The company was forced to absorb the overhead costs of running three shifts, six days a week. In addition to productivity issues, Morrill also had concerns about worker safety and high turnover. Operators would have to reach into the machine to load and unload. Sprays of coolant would often contact their skin, sometimes causing irritation and undermining the company's focus on safety.
The tedious, laborious work caused an average of three operators a month to quit. Time and resources spent training new hires were an ongoing issue.
Vaughn, Kevin Penland, process engineer, and other company decision-makers knew they needed a productivity-enhancing solution to these challenges. A Model RX130 robot from Stäubli Robotics (Duncan, SC) proved to have the right combination of speed, precision, and reliability to create true single-piece flow.
"Thanks to Stäubli Robotics," Vaughn says, "gour throughput jumped 25%, raising part production from a low of 2500 to a steady 3700 parts a day. Instead of 4000 parts in the line, there are typically just ten."
The plant's production consistency and quality rose significantly. Overtime cost disappeared. "Before we automated, we had been running three shifts everyday, six days a week," Vaughn says. "Now we've been able to shut our doors on Saturday. That saved a lot of overhead. And the five-day work week meant a happier workforce."
Penland was impressed with the ease of programming and integration he found with Stäubli Robotics. "After taking their robotics integration training, we were able to do all integration internally. That saved the $80,000 it would have cost to use a third-party systems integrator. It is very user-friendly," Penland says. "We had it up and running ourselves. Stäubli technicians just came out to do a final check with us."
Robotics has helped the company make cost reductions in a host of areas, and greatly improved its safety record, with zero injuries since the line was automated over a year ago. Parts loaders who wanted to stay on with the company moved into more satisfying jobs.
Vaughn says there were cost savings in everything from training to stocking. "We were able to set up a leaner, Kanban inventory system and make better use of space. Plus, the Stäubli robot took away some of the tedious aspects of working here, opening opportunities more suited to the skills and capabilities of our people."
Going forward, the plant has purchased another robot for a phase-two implementation, and is preparing to integrate more automation in the future for even higher efficiencies. "Morrill Motors has come a long way since the days it operated out of a basement in Ft. Wayne," Vaughn observes, "We're doing everything we can to maintain Wayne Morrill's tradition of innovation, while fulfilling the dreams of those here in the mountains who build his motors today."
Tool-Steel Processing Doubled
Böhler-Uddeholm Bearbeitungs GmbH (Düsseldorf, Germany) is primarily a service company for the tool and moldmaking industry, solving problems in the fields of semifinished tool steel, precision flat steel, system products, and individual preparation.
At present, the company has about 90 employees, processing more than 2500 t of steel per year for customers throughout Europe. These companies not only receive high-quality tool steel from Böhler, but they also benefit from the advice, know-how, and a wide range of services that Böhler offers. These services include machining tool-steel workpieces that weigh up to 20 t, surface treatment, and heat treatment, among others, to guarantee the right grade and processing for their specific needs.
Face milling both sides of the flat steel is a typical operation for the company. The operation typically consists of several plates of precision flat steel, stacked up to a maximum height of 260 mm and clamped one on top of the other, and cut simultaneously on both sides. The company was interested in finding ways to improve the process.
To help with this operation, Böhler invested in two CNC milling head systems from Th. Kekeisen GmbH and Co. (Laupheim, Germany). These specialversion machines were each fitted with two milling heads to provide a driving power of 45 kW. These units run six days a week, around the clock, and are used for simultaneous roughing/finishing flat steel cutting on both sides in batches previously cut to length. The average changeover is every 20 min.
In previous machining with round inserts (average chip volume: 195 cm3/min), the milling cutters failed to reach maximum production capacity. "These modern machines should have yielded much more production," says Stephan Kühn of Seco Tools (Worms, Germany). So, new objectives were set to increase productivity, reduce processing time, lower machining and tool costs, and increase production reliability.
To meet these challenges, Böhler decided to use a special face-milling cutter developed for the task by Seco Tools, which has been its main supplier of milling tools for over five years. The Seco team has been focused on helping Böhler to improve surface finishes, increase productivity, and make the production process more reliable, as well as trying to reduce the number of different cutting grades used.
Seco then suggested outfitting the special cutters with 16-edge standard inserts. According to Kuhn, the question became: "With the same tool life per insert and roughing inserts that were 2.4x more expensive, was it possible to achieve a substantial cost saving in the long term?"
"In an overall cost evaluation, there was absolutely no doubt," says Rainer Schuwerack, operations manager at Böhler. He explains: "The operating time required for machining precision flat steels has been halved with the new system and adapted cutting data. This has reduced our machining costs by 50%."
Roberto Reil is responsible for the use of all milling machines at Böhler. "Because of the reduction in wear of the insert surfaces of around 20%, we also achieved a corresponding cost reduction on the inserts," Reil remarks.
"It was soon realized that Seco's new Double OctoMill inserts were the right choice," says Seco's Martin Kalveram. "These inserts offer eight cutting edges on two sides—a total of 16 cutting edges. Their price/performance ratio is very good."
In addition, the Double Octomill octagonal shape offers a 135° corner angle that provides security and strength to allow more aggressive feed rates at full depths of cut. The inserts are available in five geometries and eight cutting grades, and are designed to machine almost any workpiece material.
"We still mill flat steel at 980-100 N/mm2, and the insert types cannot be changed according to the material—one grade must be good for all of them," says Rainer Schuwerack.
Grade T200M features a substrate with a fine WC grain size and a modern MTCVD coating with TiCN – Al2O3TiN and is developed to handle high-cutting-speed applications in high-alloyed tool steels.
Using the cassette version holder has distinct advantages. "If a crash occurs, we can replace relatively cheap cassettes, and the expensive carrier tool remains intact," Schuwerack explains.
According to Reil: "There is also the possibility here of axial insert adjustment for the highest possible surface quality." A special solution was essential, as a right and a left-hand cutter was needed for each double-head milling system.
After all of the demands had been defined, Seco Tools designed an optimized tool for this specific application. The insert seat is arranged in the cassettes so that the inserts act double negatively, but nevertheless operate with a soft cutting action through a positive chip angle. Eighteen roughing and two co-rotating finishing inserts in each milling cutter act as good surface-finish providers.
"The finishing inserts have a dual function—a roughing and finishing action. All the cutting edges of the Double OctoMill inserts are identified by numbers, which is an easy guide for the machine operator," adds Seco's Stefan Schütt.
The roughing inserts have eight (i.e. a total of 16) cutting edges on both sides. "Thanks to twice the chip volume per unit of time, the operating time has been halved—in other words, there has been a productivity increase of 100% and a gain of almost 170 machine hours," calculates Schuwerack.
This article was first published in the June 2009 edition of Manufacturing Engineering magazine.
Published Date : 6/1/2009