Correlation Free InLine Inspection Improves Automotive Industry Measuring Efficiency

With correlation-free measurements, ZEISS is launching a new game changing innovation that will enable the automotive industry to measure and manufacture parts with even greater efficiency. This technology marks a massive step forward on the path to the Smart Factory of tomorrow. At ZEISS, correlation-free measurements are considered a game changer because they will permanently alter inline measuring technology and ultimately the world of manufacturing. This innovation is being presented at the Control Exhibition.

ZEISS developed correlation-free measuring to ensure that component dimensions are measured reliably in the production line, beginning with the very first part. With this system, companies must no longer subsequently measure their car body components on a highly precise coordinate measuring machine (CMM) at regular intervals, and then transfer the identified deviations between the in-line and CMM measurements to the in-line measuring systems as correction values. “Correlation-free measurements will provide an entirely new foundation for in-line measuring technology and boost manufacturing efficiency,” says Dr. Kai-Udo Modrich, Head of Carl Zeiss Automated Inspection. An overview of the current in-line technology practises below will provides an understanding how automotive manufactures will benefit from this new technology.

Dimensional accuracy – the be all and end all in manufacturing

Automotive manufacturers throughout the world monitor production using in-line measuring systems to meet their own high quality standards. These systems detect geometric deviations from defined characteristics and provide 100% inspection in the production cycle. The speed and precision at which the geometric characteristics are inspected depend primarily on the optical sensors used. For example, the ZEISS AIMax 3D sensor uses fringe projection to generate a point cloud in just a fraction of a second. By obtaining dense point clouds, multiple characteristics can be measured immediately with just a single capture. Even very small characteristics can be measured precisely and on different surfaces. As is typical with all in-line systems, a flexible robot arm moves the measuring sensor to the corresponding characteristics on the individual car body components. This method ensures that the entire measuring system provides accurate results, making subsequent measurements unnecessary. With traditional in-line measuring systems, reference measurements are performed on artifacts for reliable repeatable accuracy. Active compensation is necessary for the robot arm due of self-heating and changing ambient temperatures. As robot measurements typically have minimum absolute precision, the determined measurement values are usually offset by performing a comparison measurement on a CMM. The correlation is then checked using multiple measurements. The additional workload for the CMM in the measuring lab as well as the turnaround time required pose a challenge in the automotive production plant; correlation-free measurements now make the CMM correlation redundant.

Reliability starting with the very first part

ZEISS developed correlation-free measuring to ensure that component dimensions are measured reliably, beginning with the very first part. This system uses standard cameras to detect the robots’ deviation from their specified position resulting from temperature influences.

These cameras are installed above the in-line cell and track every movement of the robot mounted ZEISS AIMax cloud sensor. Markers on the robot arms and on the base of the in-line cell allow determination of the absolute spatial position of the sensors. With the gathered information intelligent algorithms in the software detects position deviations from the original specified position and automatically performed the necessary corrections

With this new tracked robot system, companies must no longer subsequently measure their car body components on a CMM at regular intervals, and then transfer the identified discrepancies between the in-line and CMM measurements to the in-line measuring systems as correction values. For Modrich, it is clear how users will benefit: “Now manufacturers can be sure that the measured values are correct, beginning with the very first part. Having spoken with end users of in-line measuring systems, I know that automotive manufacturers have been eagerly awaiting this technology.”

“Companies can significantly expedite the ramp-up times for manufacturing new models,” says Modrich. “Since the system already delivers reliable data beginning with the first part, it lays the foundation for implementing a closed production loop between the in-line measuring station and the welding robots.”

For more information: www.zeiss.com