Gantry CMM Speeds Cycle Time While Increasing Output

A new 4-meter CMM let this shop inspect machine bases faster and more accurately.

Case Study From: 4/3/2007 Modern Machine Shop

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The gantry CMM

The gantry CMM features a measuring range large enough to accommodate the company’s workpieces in varying sizes.

Luke Norstrom

Luke Norstrom verifies the location of threaded inserts in granite.

The ability to offer customers quality products and fast turnaround times is a key competency that is required of manufacturers today. It is particularly important when it comes to retaining current business and attracting new accounts.

This is what Dennis Ethen, key accounts manager at Tru-Stone Technologies, Inc. realized when one of his main customers approached him with more challenging accuracy requirements. Cognizant of the fact that the existing measuring equipment was not capable of meeting these specifications, Mr. Ethen decided to upgrade.

“Our customers, particularly those in the semiconductor industry, are demanding higher accuracies,” Mr. Ethen reports. “Today, 0.0002-inch positional accuracy is not uncommon.”

Based in Waite Park, Minnesota, Tru-Stone Technologies Inc. provides high-precision, custom-engineered granite machine bases and accessories to prominent manufacturers of inspection and measurement equipment. Its customer base includes the semiconductor, aerospace, automotive and medical industries. According to Mr. Ethen, the rapidly changing technologies in these markets require suppliers to react quickly by being responsive to clients’ needs. This strategy has been a crucial factor in Tru-Stone’s success throughout the years, he adds.

Prior to purchasing the MMZ-B gantry CMM from the Carl Zeiss IMT Corporation, Tru-Stone used a cantilever CMM with accuracies between 0.0005 inch and 0.0004 inch to measure its granite pieces. In July of 2006, the company installed an MMZ-B with VAST scanning technology and Calypso CAD-based software. In addition to tighter accuracies, the new machine features a measuring volume of 2 by 4 by 1.5 meters, which is large enough to accommodate oversized granite blocks. The capability to withstand environmental factors such as variations in temperature and humidity levels allows the company to achieve reproducibility even in its challenging environment.

According to Tru-Stone, the machine has two major benefits: The sensor affords faster scanning speeds, while the user-friendly software enables it to create measuring plans in a relatively short amount of time.

“That’s exactly what we need to handle our current workload,” Mr. Ethen says. “With the gantry CMM, we can complete the measuring process in 45 minutes, compared to 6 hours we spent before. This represents an 80-percent reduction in measuring time. In addition, the accuracy has improved by 90 percent.”

Granite, porous and dense ceramics, carbon fiber and metals are materials that the company typically uses for its plates. Before the plates are ready for the final inspection process, the granite blocks must undergo several processes. Each incoming block must be sawed, trimmed, ground, polished and finished. Flatness and repeat readings are critical factors. When inaccuracies are detected during the final inspection, the part is then sent back to the respective step where the inaccuracy occurred. The company explains that it uses micrometers and other small measurement devices for all in-process measurements. The MMZ-B rounds out the company’s inspection resources, as it is used for final inspection.

Tru-Stone now produces about 640 jobs per month. Within a week after the gantry CMM was installed, two of the company's operators were able to familiarize themselves with the software and take advantage of virtually all of its features.

“The reporting capabilities in Calypso have reduced cycle times,” Mr. Ethen explains. “This means more product for the customer.”

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