Flatness Testing Shifts Into 21st Century at Chrysler
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
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.
- Easy to use with minimal training
- Measures more than 1 million data points in five minutes
- Generates results as customizable, color-coded 3-D