Carl Zeiss Optotechnik GmbH - Optische Messtechnik
%AM, %11 %423 %2015 %11:%Aug

3D sensor makes automatic evaluation possible

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MAHLE Behr uses fringe projection sensor for random dimension inspection in series testing.


Development partner in the automotive and engine industry
Business unit: Thermal Management

MAHLE Behr GmbH & Co. KG

Since it was established under the name Kühlerfabrik Behr & Zoller by Julius Behr and Gustav Zoller in 1905, the company has steadily evolved from its beginnings as a small family business. Its head office has been located in Stuttgart-Feuerbach since 1911. Countless developments have shaped the company's history, including the world's first wind tunnels, fresh-air heating systems, and integral A/C units in passenger cars. Part of the MAHLE Group since 2013, Behr now forms the Thermal Management business unit. In the summer of 2015, MAHLE acquired the Thermal Management division of the US automotive supplier Delphi Automotive PLC, which additionally rounds out the activities of the Thermal Management business unit. The position of company founder Ernst Mahle still serves as a model for the MAHLE Behr company today, 110 years later: "Good quality is of crucial importance. There is always room for improvement!"

It is for this reason that MAHLE Behr continually defines more effective standards for quality planning during product development and production start-up and systematically monitors internal production processes.

At the Mühlacker location, stamped stainless-steel rectangular tubes are used to manufacture EGR coolers for passenger cars and trucks. Until recently MAHLE Behr purchased these tubes from external suppliers. In 2013 the decision was made to produce the tubes in-house in the future on a production line planned specifically for this purpose. This required random dimension inspection to be carried out in series testing, combined with a new measuring system.

MAHLE Behr defined the following requirements for the new measuring system:
• The possibility of two-dimensional evaluation of the wall thickness across the stamped area of the tube.
• Two-dimensional evaluation of form and positional tolerances at the tube ends.
• Installation of an automated measuring process, since measurements on the production line are performed by system operators.

In addition, the measuring system had to be easy to duplicate so that it could be used for future production lines worldwide. Because the measurements take place in a small measuring cell directly on the production line, the system also had to be compact, occupying limited space.

These requirements were met by the COMET LƎD 3D sensor from Carl Zeiss Optotechnik GmbH, headquartered in Neubeuern, Germany. The COMET system's main criteria – its ease of operation and value for money – were not the only factors in the acquisition of the ZEISS Optotechnik 3D sensor; ZEISS Optotechnik's outstanding support and presence in the role of general project manager were also of key importance. For MAHLE Behr, there was no need for coordination between the sensor manufacturer, device design, and programmers. And because they are able to provide a global service network, ZEISS Optotechnik fulfills yet another basic requirement.

Following a year-long development period, the COMET LƎD sensor was positioned in a rigid measuring cell at MAHLE Behr. Because the fringe projection sensor is situated right next to the production line, the purpose-designed measuring cell protects the sensor from dirt and dust. Moreover, with its integrated cross-ventilation, the measuring cell provides ideal environmental conditions for optimal, reproducible measurement results. Thanks to its superb data quality and highly precise measurement results, the COMET LƎD fringe projection sensor is ideal for use in complex quality control applications.

And the measuring cell also makes it possible to carry out the required automated measuring process. The measuring process is first launched on the computer. In the next step, the user clamps the specified measurement samples one after another in the sample holder designed by ZEISS Optotechnik specifically for this purpose. This is followed by the wall-thickness measurement and geometry test.

Measuring cell   COMET L3D sensor in the measuring cell   Sample holder developed by ZEISS Optotechnik
Measuring cell COMET LƎD sensor in the
measuring cell
Sample holder developed by
ZEISS Optotechnik

The ZEISS Optotechnik system is ideally suited for measuring wall thicknesses across the embossed surface of a rectangular tube that is disjoined at the sides. This is because the entire surface can be analyzed and evaluated using false-color representation. With this view, the machine operator is able to make any necessary fine adjustments of the slider on the stamping press while still maintaining the required minimum wall thickness. Moreover, geometric dimensions are tested to enable error-free automated assembly.

Because the COMET LƎD was acquired for a new production process, no changes were made with regard to workflow.

A great advantage for employees is the measuring system's ease of operation. For MAHLE Behr, this means savings in personnel costs, since all trained employees ‒ not just professional measurement engineers ‒ can work with the ZEISS Optotechnik system.

In case of maintenance or repair of the COMET LƎD sensor and/or positioning device, MAHLE Behr needs support that is readily available around the world. The worldwide branches of Carl Zeiss Optotechnik GmbH are therefore a major plus for the company. The ZEISS Optotechnik system has been operating in the pre-production stage for some time now, with no significant malfunctions or faults.

The reliable ZEISS Optotechnik system and its powerful technology, simple operation, and helpful support were so convincing for the "Methods and Process Development Tubes" department that they purchased another COMET LƎD sensor for the measuring lab in Development, where applications for other MAHLE products are currently being developed for integration into the production measurement process in the near future.


• Automated measuring process
• Compact, powerful measuring system
• Simple measurement and analysis of wall thicknesses
• Intuitive operation of the 3D fringe projection sensor
• Worldwide support

"In regard to other measuring systems, such as CT scanners or individual laser measuring systems, considered for the measuring task at the time, the COMET LƎD is an all-round satisfying package in terms of value for money, support and reliability."
Ulf Gebhardt, Quality Planning, MAHLE Behr GmbH & Co. KG


Carl Zeiss Optotechnik GmbH
Georg-Wiesböck-Ring 12
83115 Neubeuern, Germany
+49 8035 8704 0

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