When Porsche builds car bodies, laser-beam precision is literally the way it is done. A fine, red laser beam is directed from an inconspicuous box labeled "Eagle Eye" to a car body, controlled by an employee by means of a portable console.
The “Eagle Eyes” at Porsche are hard at work in the Quality and Analysis Center at Zuffenhausen. Tobias Scheible is Head of the Car Body Measurement Technology Department. "Eagle Eye" is a visible part of what Scheible calls a “cross-departmental and cross-supplier measurement strategy". The result is that all parties involved in car construction, from development to production through to suppliers, are now speaking the same language in terms of measurement.
This is not always a matter of course in a world where dealing with fractions of a millimeter. Everyone involved has their own specific requirements when it comes to a measurement program. "At the Weissach Development Center, they need to ensure testing capability," explains Scheible. "Unlike us, they construct individual pieces.” In production, on the other hand, Porsche deals with many measurement points in a short period of time. Up to 248 vehicles roll off the production line on a daily basis in Zuffenhausen alone. A car body has more than 1,000 measurement points. There are approximately 200 at the front section, just as many at the rear of the car and a good 100 on a door, lists Scheible.
As a result, each department has established its own highly- specialized measurement system over the years, all as perfect as possible. But they are transferable only to a limited extent. It took an immense effort to standardize the different data structures and algorithms. "But it was worth it," says Scheible. Now, the first measurement program is created in parallel with the development of a new vehicle. This takes around nine months. When the Production Department comes into play around a year before production starts, the process is much quicker:
"Building on the available values, we can create our measurement program in a few weeks by means of an optimization loop instead of taking half a year, which was the case previously,” explains Scheible.
This measurement program is the brain of "Eagle Eye." The optical sensor measures up to five times faster than its predecessor, using the red laser beam to scan surfaces, accurately measure the curvature, height, depth and width of a component, check edges and transitions, holes and pins, and then send the data to the software. The software compares the measured data with the values from the CAD (Computer-Aided Design) software. The "data control model" is the original vehicle for each series, which corresponds exactly to the CAD data. It represents the ideal conception of a car body, which cannot exist in reality because deviation is the normal condition in a world that can be calculated only to a limited extent. For example, the cathodic dip coating process heats the sheets, which can change their shape.
The calculation limit at Porsche is in the range of fractions of a millimeter; which demonstrates just how close the company comes to perfection. This requirement also applies to suppliers who, under the new measurement strategy, are integrated directly into the system. This means that deviations can be identified and corrected at an early stage, removing the need for duplicate measurements. That’s Porsche precision in action.
Date Posted: June 11, 2018