Shop Solutions: Precision Measurement Boosts Tool Quality
Founded in 1966 to manufacture and regrind solid carbide tools, Carbur Tool (Coldwater, MI), a seven-person carbide-tool-making shop, develops special metalcutting tools, and regrinds and modifies tools in HSS and carbide. Quantities in a run may be only one tool or dozens. "Each tool we make is unique," says Keith McGuire, company president.
For each tool it grinds today, Carbur can now provide verification to its customers that the tool is produced to spec. That's something it could not do less than a year ago, and the inability to do so threatened the future of the family-owned company.
Carbur found that a comparator or a micrometer were no longer enough to control tool quality. "Looking at tools through an optical comparator and writing down the apparent tolerances just was not going to be acceptable to our customers, because it's so operator-dependent, and therefore unreliable," Keith McGuire says. "That was the way my father worked, but it's no longer acceptable. There's no 'close enough' anymore."
"We needed to verify step tools, taper tools, core depth, hook, gash and rake angles, primary and secondary angles, margin widths, chisel angles, k-lands, chamfers, drop on a two-flute drill, profile in a form tool, and more," says Jon McGuire, Carbur's vice president.
When the company reached the point where it truly had to improve the consistency of its tool making, it called Zoller Inc. (Ann Arbor, MI). "We asked Zoller to inspect a range of more than 30 sample tools to show us the capabilities of their technology. We spent more than a day in their demo facility. When I work with a vendor, I really want to learn the equipment so we can take full advantage of its capabilities," says Jon McGuire.
"We can now verify true dimensions on radii and tapers, flute depths, or hooks that before we could only view on the comparator," says Jon McGuire.
The Zoller Genius 3 is a five-axis CNC universal measuring machine capable of complete measurements in 2-D or 3-D using digital image processing. Its positioning accuracy is 0.001-mm (0.000039") linear and 0.01º in the B axis. The measuring range is 600 mm in length, 230 mm in diam, land width, rake-angle circumference, and axial measurement to 470 mm. In the Z axis it has a range of 600 mm, X axis 175 mm and Y axis 100 mm.
For 2-D measuring, a camera with telecentric objective and 50 X magnification, plus image processing software with fully automatic cutting-edge shape detection, lets Carbur measure its tools and their cutting edges. For automatic 3-D measurement, an incident-light measuring technique checks effective cutting edge angle and tool orthogonal clearance angle at the cutting edge, as well as other parameters. A CNC-positioned camera with a 200 X magnification and segmented controlled incident light is used for this purpose.
Saturn 3 measuring software from Zoller permits presetting and measurement of tools, and automatic inspection of cutting tools and grinding wheels. "For the first time we can ensure that the grinding wheel profiles will accurately generate the desired tool geometry to micron tolerances. The machine's Windows NT operating system is very helpful to integrating tool inspection and manufacturing.
"This is the capability that we ultimately used to rescue our quality," says Jon McGuire. "We used the Genius to measure tools and the corresponding grinding wheels to reduce variation among tools, and ensure that the wheel is correctly qualified to generate the tools.
"We discovered that even 0.005" [0.127-mm] wheel wear on the tool grinder was enough to cause the tool to be out of tolerance," he continues. "The Zoller is repeatable within 2-µm concentricity. With its results we can control our grinding much more closely."
Operators check tool features such as core diameters and hooks on the unit. "If the machine says we have a 50º hook, but we have 10º punched into the CNC, I trust the data, and we adjust the machine accordingly," says Jon McGuire.
"For our main customer, Asama [Coldwater, MI], we manufacture 33 different styles of tooling. As a supplier of engine components and front knuckles to Honda, they were pushing us to verify tooling, but I took it one step further," says Jon McGuire. "I set up all their tool inspection programs identical to what we use here to eliminate variation among measurements and ensure apples-to-apples comparisons."
"We also developed an on-line reporting system for our customer that allows them to view tolerances and measurement results for each tool we make for them. We upload the inspection data from our Zoller to our Web server and, with an interface at their end, our customer can view and verify the results of each tool inspection nearly as soon as the tools are produced," he explains. "This is especially important for ISO-certified manufacturing.
"When tools are returned for regrinding, we can measure the tools and compare that data to the original manufacturing data and the number of pieces produced to get an idea of tool wear rates. This allows us to see where we could improve the tool design," Jon McGuire observes.
To produce tools from solid carbide, Carbur operates centerless grinders as well as CNC tool-and-cutter grinders made by ANCA (Wixom, MI) that are equipped with ANCA's Cimulator 3D tool design and software. The company has also recently invested in a robotically loaded CNC tool-and-cutter grinder to permit the lights-out production of tools of multiple sizes and styles on second and third shifts.
"The entire shop is included in a wireless network," Jon McGuire observes, "so I can actually view from home everything that is going on at any time. I can communicate with each machine, and troubleshoot from home through the system if necessary.
"All customer drawings are in our database; if we need to make a tool, we retrieve the data, load it into the grinders and the inspection machine, and make the manufacturing data available to the customer to view on line, including any changes needed, and who requested the change and when."
New Grinders Drive New Business
Until 1998, Asteroid Grinding (Chicago) had 33 centerless grinders, and provided precision grinding and polishing services on jobs that other shops outsourced. When presented with the chance to make a large-volume hydraulic part run for an automotive company, Jim Vigue and his partners, Mike Vigue and Wayne Pope, jumped at the opportunity.
"We accepted the job knowing we had to invest in new equipment to support it," Vigue says. "But this investment in new grinding technology was also an investment in the company's future." The company purchased a fully automated GL3A-25II cylindrical grinder from Toyoda (Arlington Heights, IL), and had it installed and running around the clock within three weeks. As a backup machine to the GL3, Asteroid purchased a Toyoda model GL4A-50EII.
Asteroid's initial fulfillment of the hydraulic part order led to a long-term relationship with the OEM. Five million cycles and six years later, Asteroid is working on the part's redesign for future production.
"That initial purchase laid the foundation for our transition into more sophisticated grinding," Vigue explains. "In the past eight years, we've bought eight Toyoda grinders. They've enabled us to take on more complex and higher-paying work than we could previously support."
Asteroid Grinding now produces components for various OEMs, including parts for the medical, aerospace, automotive, and communication industries. The Chicago-based, 16,000 ft2 (1486 m2) facility operates 24 hours per day, five days per week.
The company has developed in-house capabilities to enhance its operation. Asteroid's in-house inspection and measurement department guarantees finished parts meet the required tolerances. Once a job is running, quality checks are performed every 30 min during production.
Tool Costs Up, Process Cost Down
For 25 years, JR Higgins Associates (Acton, MA) has been manufacturing specialty vehicle signs and providing contract machining services to its customers. "Our goal was to reduce cycle time and tooling costs on a mount pivot abduct we were manufacturing for one of our customers, when we realized that we had an opportunity to significantly improve our overall bottom line," says John Higgins.
JR Higgins had been manufacturing the 6061 aluminum mount pivot abduct on a VMC using a two-tool milling process. The part required a profile milling operation to a finished axial depth of 1.650" (42 mm) and a radial width of cut of 1.00" (25.4 mm) using a 3/4" (19-mm) diam tool. In total, the company had to cut and remove a 14" (356-mm) length of material from each part.
The cut was originally accomplished in a total of six passes with two standard tools. A traditional roughing-type HSS end mill was used to remove most of the material in four roughing passes to an axial depth of 1.650" with a 0.250" (6.4-mm) radial width of cut. Then, a conventional two-flute end mill made the final two finishing passes to the finished depth of 1.650," and a finished radial pass of 0.01" (0.25 mm) per side.
"These two tools got the job done, but we realized that there was room for improvement--especially when we considered the fact that the two end mills we were using did not have the same tool life," says Higgins. "The roughing end mill substantially outlasted the finishing end mill in the application by a ratio of 2:1; so we had a situation where one cutter would sit while the other was being replaced. This delay could add up to hours of lost production every year, so we had to find a way to recapture that time."
Realizing that they could engineer a more efficient way to manufacture this component, JR Higgins teamed with local distributor Robert E. Morris Co. (Farmington, CT). "I expected them to bring us less expensive tools to help cut costs," said John Springer, Programmer for JR Higgins. "Instead, they brought us an engineered high-performance product solution."
High-performance tools are often more expensive due to the engineering and advanced manufacturing techniques required to produce their intricate geometry. To measure the impact a high-performance tool would have on its operation and determine its potential value, JR Higgins Associates tested a 3/4" Ski-Carb from SGS Tool Co. (Munroe Falls, OH) in their mount pivot abduct application.
The patented Ski-Carb high-performance end mill was developed for increased productivity when machining aluminum, plastic, and other nonferrous materials. Springer programmed the Ski-Carb to perform the roughing operation in three steps instead of four. He also programmed the Ski-Carb to split the 1.650" depth of cut in half to a 0.825" (21-mm) axial depth of cut, and increased the radial width of cut to 0.375" (9.5 mm). They ran the Ski-Carb at 15,000 rpm and 150 ipm (3.8 m/min).
Test results proved that the SGS Ski-Carb was able to cut the finishing process in half. As a result of the improvements made during the roughing portion of the operation, the finish process was reduced to just one pass to achieve the finished dimensions of the profile cut. "Best of all," says Springer, "finishing was accomplished by the same tool we used for the roughing, and it ran at 15,000 rpm and 150 ipm while removing 0.01" per side." The Ski-Carb was able to finish the part to the full depth of 1.650" in one pass, as opposed to the old process, which required two passes at 7000 rpm and 75 ipm. The high-performance Ski-Carb end mill offered JR Higgins Associates a time savings of more than 70% by reducing cycle time from 1 min 15 sec to 22 sec.
After switching to the SGS Ski-Carb, the company experienced a cost savings by eliminating the number of tools held in inventory, eliminating the downtime resulting from tool changeout, decreasing cost per part by 85%, increasing material removal rates by 82 in.3/min, and reducing costs involved with maintaining the original two-tool inventory.
"The initial success we had with the SGS Ski-Carb told us that we could implement the high-performance tooling approach when machining these kinds of parts," says Springer. Since then, JR Higgins has progressed to a horizontal machining operation using a tombstone fixture that allows them to produce 36 parts per cycle as opposed to two using their original approach.
RP Boosts Student Racing Efforts
Each year, the Society of Automotive Engineers (SAE; Warrendale, PA) holds a competition during which SAE student members conceive, design, fabricate, and compete with small formula-style racing cars.
This year, the Formula SAE (FSAE) team from Saginaw Valley State University (SVSU; University Center, MI) redesigned their car from the ground up to reduce weight and improve efficiency. In addition to replacing the sheetmetal on the car with carbon-fiber panels, team members reviewed and redesigned other components with an eye toward reducing weight while maintaining design integrity.
Spherical ball ends for the car's suspension system were among the components that came in for redesign. In 2004, the team burned more than 56 man-hours to build wax patterns needed to produce the investment-cast steel parts. With the competition a few months away and a local company willing to produce the parts, the students needed a way to reduce pattern-building time.
They turned to the SVSU Rapid Prototyping Center and its Solidica Formation Ultrasonic Consolidation RP system (from Solidica Inc., Ann Arbor, MI). The system uses ultrasound to make solid-state welds in thin aluminum tape to create solid metal parts that are then machined with very small end mills with short flute lengths. According to the company, this process allows production of parts with features such as sharp corners, without secondary EDM processing.
The machine uses cutters as small as 1/32" (0.8-mm) diam with a 0.25" (6-mm) flute length to create 1/64" (0.4-mm) corner radii in pockets as deep as 8" (200-mm) and as narrow as 3/64" (1.2-mm).
Professor Robert Tuttle, who runs SVSU's RP facility, spoke with Solidica engineers about the possibility of producing molds for the wax patterns using the company's equipment. "One of the benefits of the Solidica process for mold construction is that it provided the team with greater flexibility in developing the alternative design," Tuttle says.
SVSU senior Jenny Patengill, who co-captained the 2005 FSAE team with senior Philip Degner, agreed. "That's the big benefit; it just takes too long using conventional techniques," she said.
Solidica worked with the students to produce pattern molds in less than half the total time it had taken the previous year--a total of 23 man/machine hours (five man-hours and 18 untended machine hours). The process produced multiple mold halves on the same unfixtured platform. Bay Valley Investment Casting (Saginaw, MI) used the molds to produce wax patterns for the 4140 steel spherical ball ends, which were then finish-machined by students.
The result of all the team's efforts was an eighth-place showing out of 140 teams in the competition, a big jump from 2004's 59th place.
This article was first published in the October 2005 edition of Manufacturing Engineering magazine.