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CMM solves control and throughput problems for EDM jobshop

April 1, 2002
Quality control and throughput were proving a problem for Wire-Tech Inc., a 10-person EDM job-shop in Tempe, Ariz. The firm, which has 12 CNC machines, including eight wire EDMs, primarily serves the aerospace and plastic-injection-molding industries. As

A Starrett Premis CMM and its Apogee software not only improves quality control for Wire-Tech, a Tempe, Ariz.based company, but also wins the firm new customers. These photos (clockwise from top left) show the entire system, an operator using the CMM, and a closeup of a part being checked.

Quality control and throughput were proving a problem for Wire-Tech Inc., a 10-person EDM job-shop in Tempe, Ariz. The firm, which has 12 CNC machines, including eight wire EDMs, primarily serves the aerospace and plastic-injection-molding industries. As such, accuracy is vital to Wire-Tech's success, and conventional quality-control methods weren't measuring up to its needs.

For example, it was nearly impossible to check airfoil vanes to within 0.0005 in. using profile gages or a comparator with a mylar overlay. Large vane shapes couldn't be magnified to a high enough power to see profile tolerances, and it often took 6 to 8 hours to take and record measurements. The company knew it had to make changes to remain competitive.

The shop's two options were custom fixtures or a coordinate measuring machine. It chose a CMM because of measuring speed, versatility, and accuracy.

After some study, the company purchased a Starrett Premis CMM with a 24 2418-in. (X, Y, Z) measuring range. "Unlike other machines that have aluminum members," says Wire-Tech President Rick Erickson, "the Premis machine had a ceramic Z axis and hollow granite components such as the bridge and supports that make it sturdy and more thermally stable."

To check accuracy and repeatability, Wire-Tech measured sample parts from a major customer on the Premis. It then had those parts checked on the customer's CMM, which is purportedly the industry's most highly accurate type. The Premis was repeatable to within 0.000004 in. In addition, the CMM accommodates splines and irregular shapes that could not be checked on a surface plate.

The Starrett Premis CMM not only improved accuracy but also slashed inspection times. "Even though some EDM jobs require hundreds of electrodes, the Premis lets us check them all in at least half the amount of time, and more accurately, than before," says Erickson.

A CMM software package, called Apogee, came with the Premis. With Apogee, Wire-Tech checks electrodes by viewing a solid CAD file. "Customers can also view the same CAD file and receive a print, which really increases their comfort level," says Erickson.

The Premis with Apogee has been instrumental in bringing in new customers and enhancing Quality's relationship with existing ones because the shop met and certified challenging accuracies in a short time. This makes them a credible source and allows them to compete more effectively with larger shops.

L.S. Starrett Co.
Athol, Mass.
www.starrett.com