Quality Digest      
  HomeSearchSubscribeGuestbookAdvertise August 1, 2021
This Month
Need Help?
ISO 9000 Database
Web Links
Back Issues
Contact Us
Departments: Quality Applications

Flowcharting Keeps NASA Processes Grounded in Efficiency


Flatness Testing Shifts Into 21st Century at Chrysler


Flatness Testing Shifts Into 21st Century at Chrysler
Coherix Holomapper

Early maritime explorers plotted their courses with relentless devotion to the stars for two reasons: It was the only empirically proven way to ensure the sailors would reach their destination, and it prevented the horrifying prospect of being blown off the edge of the world. The “flat planet” theory was more a product of unsophisticated vision than anything else. Had the early renaissance produced satellite photography, Christopher Columbus may well have seen his role in history reduced to that of a Genovese dockworker. Nevertheless, the 15th century fell well short of space age technology, leaving Columbus to brave scurvy and Atlantic tempests to prove his point. The world, it seemed, was not flat.

Columbus, the patriarch of flatness testing, is history. Today we have the Coherix Holomapper.

Flatness measurement is a critical component to Chrysler Group’s transmission assembly. At the company’s transmission plant in Kokomo, Indiana, each part is machined within a strict tolerance range set by product design engineers. Traditional CMMs identified and maintained acceptable flatness standards, but Chrysler had set its sights on even greater precision and quality. Part of the process involved recognizing the inherent fallibility of certain systems. Although Chrysler’s CMMs were accurate, they were bound by their limitations. With a restricted number of contact points, there was an entire element below the surface that the CMMs were missing. Chrysler rectified the problem with the implementation of Coherix’s Holomapper.

Holomapper measures the surface flatness of precision-machined metal parts with a multiwavelength laser system that generates high-resolution 3-D images. Its tunable-wavelength laser gathers data about the part in its field of view by flooding the part surface with laser light, which is then bounced back to a scientific-grade digital camera. Holomapper processing software then converts the captured data into a 3-D height map of the part surface.

“Flatness specifications can be misinterpreted easily,” says Ted Wiles, quality engineering supervisor at the Kokomo plant. “Before the Holomapper, we were unable to get the qualitative and quantitative information we needed to improve our machining patterns. Now we’re able to adjust our part cutting machines with precision we’ve never had before.” Holo-mapper provides users with measurement of more than 1 million data points over a surface area of up to 12 ¥ 12 in. This type of advanced analysis typically has a tradeoff with respect to run time, but the Holomapper can complete its measurement in less than two minutes. “We now have a tool we can trust as a part of our quality control process,” notes Wiles.

The 3-D images of parts measured by the Holomapper are integral to the quality control process, giving engineers a complete view of the cutting pattern. “In minutes I can get a comprehensive view of the part,” says Doug Arnold, quality control engineer. “Based on our ever-increasing set of tolerances, I can use the Holomapper’s software to pass or fail a part by color designation. To be able to do this in such a short timeframe allows us to make real-time adjustments to the machines on the line.”

By reducing downtime and augmenting precision simultaneously, Holomapper has afforded quality engineers at Chrysler another line of defense against production flaws. Along the way, Holomapper proved that advanced vision is as important to flatness testing today as it was in 1492.

Coherix Holomapper


  • Easy to use with minimal training
  • Measures more than 1 million data points in five minutes or less
  • Generates results as customizable, color-coded 3-D images