Tech Briefs
Measuring up the Neon

The Metronor system for pre-production verification of body assembly tools gave DaimlerChrysler true CMM capability on the Neon shop floor.

The manufacturing start-up phase for DaimlerChrysler's new Neon has been termed a benchmark in the company's automotive launch efficiency. Instrumental in this success was the company's use of a Metronor system that establishes and verifies manufacturing process quality prior to production. The extensive use of the system for pre-production verification of body assembly tools was an important reason for the minimal plant closure time and high initial quality of the new vehicle.

As product and development cycles get shorter and profit margins shrink, it becomes critical to keep lost production to a minimum during model changeover to make new models profitable. In the automotive body-in-white area, one of the main obstacles to a short launch is production line tune-in and problem solving, which often requires the plant to be shut down for months.

In 1994, Chrysler's Small Car Platform started planning for the 2000 Neon. An ambitious production line changeover goal of two weeks was defined. For the Gage and Process Team, it was clear that the goal could not be met using traditional body-assembly-tool certification methods. A plan was designed to enable the team to identify, analyze, and eliminate process problems as early as possible. By the time the line was installed, there would be almost no time for problem solving.

The 2000 Neon Gage and Process plan focused on five areas:

• Close the computer integrated manufacturing (CIM) loop through real-time comparison of all critical features on the assembly tools to the actual CAD model for the new car. This required a measurement system able to download data that could be compared to CAD models.
• Detect all assembly tool build errors by probing critical features directly with a traditional, stationary coordinate measuring machine (CMM).

This required a transportable measurement system with true CMM capability, even for "hidden points."

• Verify that all assembly tools' ability to locate sheet metal consistently through a dedicated tool-repeatability verification procedure. This required a feature like the Metronor's light-emitting diode (LED) target measurements, which enables fast and efficient measurement of many points simultaneously.
• Develop efficient means of determining the root cause for assembly process problems through verification of tool, sheet metal, repeatability, and related influences. This required the measurement system to handle tool, sheet metal, and repeatability measurements with equal ease.
• Find a way to certify 50 major assembly tools in two weeks as would be required during the plant closure. This required a measurement system with high accuracy, reliability, and efficiency in a demanding plant environment.

In earlier Chrysler projects, laser trackers had been used for body-assembly-tool certification. However, with the heightened ambitions for the 2000 Neon project, the Metronor system was identified as the only measurement system that could meet all the requirements simultaneously. A partnership with subcontractors QMC Inspection Solutions of Auburn Hills, MI, Metronom of Monroe, MI, and RYMAC of Columbus, OH, enabled Metronor and the Small Car Platform to develop all the necessary methods and procedures.