In some manufacturing environments, quality technicians must work with tolerances as small as 0.005 millimeters when verifying part dimensions. Mike Rovillo, senior quality engineer at VDO North America (Cheshire, CT) knows how tricky it can be to measure such microscopic dimensions.

VDO, an automotive parts manufacturer for General Motors, Ford, DaimlerChrysler and some European and Japanese automakers, needed to find an inspection system within 60 days that could conduct part measurements for a prototype fuel pump. "We needed to launch the new fuel pump on a very aggressive timeline," Rovillo says.

The demanding development timeframe required a measurement system investment that would create immediate returns in the form of accuracy, speed and consistency in measuring the fuel pump prototypes. To meet that demand, VDO purchased a Contura scanning coordinate measuring machine (CMM) supplied by Carl Zeiss IMT Corp. (Minneapolis).

"I chose the Contura CMM because of its scanning capabilities, ease of use and compatibility with other computer platforms," Rovillo says. "I also needed a system that up to nine different quality technicians could use to easily collect large amounts of data and utilize process signal information in a high-production environment."

Before the Contura, VDO technicians took measurements using a touch probe CMM. Compared to that process, the Contura has reduced fuel pump inspection time from four hours to four minutes. Rovillo says that even though the company has a full suite of standard measuring equipment, the Contura is used for high volume machining support, new products and urgent requests because it can handle these types of tasks with ease.

VDO has programmed the machine to measure hundreds of fuel pump housings and covers using the Windows NT-based Calypso software. "Once the CMM is programmed to run measurement routines on a particular part, it's easy for our operators to conduct inspections," says Rovillo. "We've been able to obtain real-time process control information based on product characteristics, which helps reduce part variation and eliminate defects."

The Contura accurately measures part dimension, form and position in one setup. It also scans thousands of data points per minute and consistently measures tolerances as low as 0.005 millimeter, says Rovillo. The CMM combined with the Calypso Windows-NT platform enables VDO to gather enormous amounts of data that can be downloaded automatically to a statistical process control program.

Because of the range of dimensional characteristics Contura offers, VDO is measuring more part features than before. "If I need to measure a specific point at the bottom of a feature that I can't see, like a V groove or radius, the probe self-centering function indicates when I've reached the bottom of that part feature and accurately measures the characteristic," Rovillo says. "This is an important characteristic that we didn't have previously."

VDO is able to conduct part measurements of a variety of parts accurately and within a certain timeframe. "We needed the flexibility to measure a wide range of parts in an automated environment," Rovillo says. "The accuracy, repeatability and the data density we get with scanning offers all the performance we asked for and more."

Carl Zeiss IMT Corp.
(800) 752-6181