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PTB presents a novel cam standard and mobile measuring system for the traceability of large components

CONTROL, May 4 to 7, Hall 1, Stand 1313: PTB offers concepts and standards to ensure the measurement quality for both cam shafts and large components

26.04.2010

The dimensions of a cam shaft can have a decisive effect on the fuel consumption, the exhaust emission and, finally, the power of a combustion motor. A deviation of a few hundredths of a millimetre already puts the quality into question and forces may develop which further wear and an increased fuel consumption. But: how exactly can the dimensional accuracy of a cam shaft be actually determined? Although corresponding measuring instruments, including the respective software, are available, the determination of the accuracy of measurement has so far been guaranteed only to a limited extent. In cooperation with a partner from industry, scientists of the Physikalisch-Technische Bundesanstalt (PTB) have developed a cam standard on the basis of which corresponding measurements can be traced back with due regard to practice. This allows the quality control for cam shafts to be clearly improved. Between May 4 and 7, PTB will present the new procedure at Stand 1313 in Hall 1 at the CONTROL in Stuttgart.

Design drawing and view of the cam standard developed by PTB, which allows measurements in industry to be traced back with due regard to practice.

The standard, which is manufactured of tool steel, has the form of a heavy cam shaft and a weight of 1.4 kilogram. Its dimensions have been determined at PTB with a tactile form measuring device and a tactile coordinate measuring machine. Soon, the cam standard will be available to potential calibration service providers or to interested parties from the automobile industry, to verify the quality of corresponding tactile measuring instruments.

As the largest errors in the measurement often do not occur during tracing but in the evaluation of the complex measurement data, PTB also provides test data sets which allow the quality of the software used in industry to be checked. When the test results agree with the reference result of PTB (deviation 0.1 micrometer at the most), the software test is regarded as successfully passed.
Generally, PTB is dealing with the question of how novel measuring systems - e.g. laser scanners, indoor GPS or high-precision 3 D interferometry - can be traced back to determine and improve the quality of the measurement data. Within the scope of the European research project "Metrology for New Industrial Measurement Technologies" (NimTech), in which four other metrology institutes are involved, priority is given in particular to transportable systems which can be used directly in the production environment and cover structures with dimensions of up to ten meters. Fields of application are, for example, the wind power industry and the aircraft industry. In this field, PTB and its partners have developed both reference objects and numerical standards which are available to manufacturers of measuring instruments for the evaluation of their measurement software.

Contact at PTB:
Dr. Frank Härtig, Working Group 5.3, Coordinate Measuring Technology,
phone: +49 531 592-5300
E-mail: frank.haertig@ptb.de