The quicker inspector

New CMM comes with its own computer system

A North Carolina shop checks a variety of milled, turned and round parts. It has greatly improved process control and cut its inspection costs by about $25,000 a year. This improvement comes as a result of upgrading to a manual coordinate measuring machine (CMM)--specifically Mitutoyo America Corp.'s M-507 CMM.

Wirtz Wire EDM Inc., Hendersonville, NC, has customers from the aerospace, automotive, mold and die, turbine and fluid power industries. Before acquiring this new CMM in late 1999, Wirtz checked dimensions using an optical comparator, hand tools, and elaborate set-ups. Previously, operators spent an average of two hours per shift inspecting; now, the same job takes only 15 minutes per shift. The methodology change has reduced inspection labor costs by 75 percent, so Wirtz recovered the $20,000 price of the machine in less than a year.

Patrick Wirtz, president of Wirtz Wire EDM Inc. of Hendersonville, NC inspects a complex part on a Mitutoyo America Corporation M-507 manual coordinate measuring machine.

"Before, we would use a comparator, if the part would fit on it, or do set-ups, with Jo blocks and gage pins, height gages, and indicators," says Patrick Wirtz, Wirtz Wire president. "Sometimes, this was very time-consuming."

Checking certain parts, such as cone shapes, was particularly cumbersome and expensive, beforehand. In addition to a 15-minute inspection set up time, a gage ball would have to be purchased to measure the inside of the cone. "We'd fit the ball down and then depth-mike to the ball's top. And we'd lose a day waiting for the $60 ball to be delivered," says Wirtz. "Then, it would only be used once. A new gage ball, which resembles a large ball bearing, was needed for each time a different size cone required measuring."

Investing in a CMM became a cost-effective alternative to buying a variety of new measuring equipment. The CMM replaced all the bench tools, gaging equipment and fixtures the shop had been using.

Also interfering with efficiency was the manner in which inspection reports were done. "Before the M-507, we had to generate hand-written reports, and do a lot of manual computations which took time away from chip-making and introduced a lot of source, or system errors," says Wirtz. "Eventually, our bottom line was being hit." The built-in reporting software in the CMM took care of all the paperwork.

Seeing is believing

Going the CMM route became an obvious technical and financial necessity for fast-growing Wirtz. Originally a wire EDM shop, it has expanded into conventional EDM, EDM drilling and CNC machining. "We're equipped to do just about anything," Wirtz says. "Because our company specializes in doing high precision work, we need measuring equipment that can handle extremely tight tolerances."

At first, Wirtz leaned toward another CMM maker, and had even gone as far as to issue a purchase order. But he canceled the order after seeing what Mitutoyo America offered. Within 20 minutes of viewing the M-507 at the Mitutoyo Metrology Center in Charlotte, NC, he knew he had found a better solution.

Wirtz chose the M-507 because of its ease of use, superior accuracy, size and software for the money. "It is never out more than 0.000050´´; the machine we almost bought would be out 0.0004´´ measured by a gage block," says Wirtz. "The M-507, at 20´´ x 28´´, gives us 8´´ more travel than the other CMM."

But its software was the biggest issue. The M-507 has its own computer system while the competition just offered a keypad. And the power of the computer specifically impressed him. "It's able to do things you don't think it can do," he says. "It is able to easily check things that you think are going to be very difficult."

He especially likes the software's ability to contour with a hard probe and make a print of it. The software is able to follow a contour automatically to as many points as the inspector wants and finish the job in about one minute. "With the other CMM we were considering, you had to put in your own points. But the M-507 gives you a consistent pattern of points and it spots them together for you," Wirtz says. "It can also handle out-of-round situations, which our shop often faces, enabling them to be enlarged."

Inspection as profit center

Another major plus of having the software is that it automatically writes a program for each part the CMM measures. The next time it checks the part, no calculations need to be done. "All we do is put the part in, go down to the program and hit RUN," Wirtz says. "Once you've done one part, it tells you what to do on the next part. It tells us what to pick up. All you have to do is move the probe around." Doing non-coplanar measuring is easy too.

Compiling inspection reports for customers is now a moneymaker for the shop. Before, doing the reports was a financially draining, time-consuming process. "We now print the report out and it looks professional," says Wirtz. "In fact, other shops are now coming to us to do their reports. They like that we can print reports out automatically, much faster than they can."

When acquiring the M-507, the only worry Wirtz had was how complicated the software might be to learn. He was relieved to discover that it was similar to drawing on a CAD system. Because the CMM basically programs itself, it was easy for his line operator--who had limited computer background--to learn.

Easy operation

In fact, learning to use the CMM was an altogether simple process for Wirtz. Since he was familiar with the fundamentals of operating the M-507, he quickly became familiar with the more advanced operating aspects.

In addition to Wirtz, two operators use the machine. The Mitutoyo M-507 checks parts coming from the EDM units, a turning center and a vertical machining center. On average, the shop operates 11 hours a day, five days a week.

Here, the probe of Wirtz Wire EDM's Mitutoyo M-507 goes through its paces.

Sometimes operators check every part in a lot and sometimes they sample, depending on the customer. If a lot has 100 parts, they might sample 25 of them; if there are 20 parts, they might check all of them. The average lot size from Wirtz's wire EDM machines is around 300 parts, but lots for the turning center range up to 10,000 parts. The smallest lot, for prototypes, is one part. The vast majority of parts are under 12´´ square or rectangular but some parts range up to 28´´. Typically, they check five to 20 features per part.

Wirtz is also delighted with the level of service he receives when he calls Mitutoyo America for technical assistance. "They're very knowledgeable and I always get an answer right away when I call. I don't have to wait for a reply. They're especially good at providing alternative solutions to problems."

In the future, he plans on using more of the Mitutoyo M-507's surface characterization features and doing more comparative measurements. "It can do so much," Wirtz says. "And we look forward to its continuous use as our company grows."

Mitutoyo America Corp., Aurora, IL, http://www.OneRS.net/107tp-334 or circle 334

Wirtz Wire EDM Inc., Hendersonville, NC, http://www.OneRS.net/107tp-332 or circle 332