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X-ray Computed Tomography (CT) has become an important technology for quality control of industrial components. As with other technologies, e.g., tactile coordinate measurements or optical measurements, CT is influenced by numerous quantities which may have negative impact on the accuracy and repeatability of dimensional and geometrical measurements. The aim of this paper is to discuss different methods for the correction of scaling errors and to quantify their influence on dimensional measurements. Scaling errors occur first and foremost in CT systems with no built-in compensation of positioning errors of the manipulator system (magnification axis). This article also introduces a new compensation method for scaling errors using a database of reference scaling factors and discusses its advantages and disadvantages. In total, three methods for the correction of scaling errors – using the CT ball plate, using calibrated features measured by CMM and using a database of reference values – are presented and applied within a case study. The investigation was performed on a dose engine component of an insulin pen, for which several dimensional measurands were defined. The component has a complex geometry and is made of brass, which makes its measurements with CT challenging. It is shown that each scaling error correction method results in different deviations between CT measurements and reference measurements from a CMM. Measurement uncertainties were estimated for each method, taking into consideration the contributions related to the applied correction method. The newly suggested approach using the database appeared to work well, indicating, that if the properties of a CT system under investigation are monitored using a reference object (ball bar in our case), a correction factor based on individual selected magnification factors can be applied for scaling error correction of any object, and thus no additional scanning of a reference object is needed.

DOI: 10.1016/j.cirpj.2014.04.002

Zeitschriftenartikel

P. Müller, Jochen Hiller, Y. Dai, J. Andreasen, H. Hansen, L. Chiffre

Estimation of measurement uncertainties in X-ray computed tomography metrology using the substitution method

CIRP Journal of Manufacturing Science and Technology, vol. 7, no. 3, pp. 222-232

2014

This paper presents the application of the substitution method for the estimation of measurement uncertainties using calibrated workpieces in X-ray computed tomography (CT) metrology. We have shown that this, well accepted method for uncertainty estimation using tactile coordinate measuring machines, can be applied to dimensional CT measurements. The method is based on repeated measurements carried out on a calibrated master piece. The master piece is a component of a dose engine from an insulin pen. Measurement uncertainties estimated from the repeated measurements of the master piece were transferred on to additionally scanned uncalibrated workpieces which provided the necessary link for achieving traceable measurements.

DOI: 10.1016/j.procir.2013.08.022

Zeitschriftenartikel

P. Müller, A. Cantatore, J. Andreasen, Jochen Hiller, L. Chiffre

Computed Tomography as a Tool for Tolerance Verification of Industrial Parts

Procedia CIRP, vol. 10, pp. 125-132

2013

Computed tomography (CT) is becoming an important technology for industrial applications, enabling fast and accurate control of manufactured parts. In only a few minutes, a complete 3D model of a part may be obtained, allowing measurements of external and internal features. This paper presents results of tolerance verification of a plastic housing for an insulin pen manufactured by Novo Nordisk A/S. Calculation of measurement uncertainties was taken into account in decision making regarding the specified tolerance limits. Variables in terms of CT systems, data sets, and evaluation software are considered in this study.

Beitrag (Sammelband oder Tagungsband)

P. Müller, Jochen Hiller, A. Cantatore, M. Bartscher, L. Chiffre

New reference object for Metrological performance testing of industrial CT systems

Proceedings of the 12th euspen International Conference (Juni 2012, Stockholm, Schweden)

2012

Vortrag

P. Müller, Jochen Hiller, A. Cantatore, M. Bartscher, L. Chiffre

Investigation on the influence of image quality in X-ray CT metrology

Conference on Industrial Computed Tomography (ICT), Wels, Österreich

2012

DOI: 10.1051/ijmqe/2012011

Zeitschriftenartikel

P. Müller, Jochen Hiller, A. Cantatore, L. Chiffre

A study on evaluation strategies in Dimensional X-ray computed tomography by estimation of measurement uncertainties

International Journal of Metrology and Quality Engineering, vol. 3, no. 2, pp. 107-115

2012

Nachhaltig Angewandte Naturwissenschaften und Wirtschaftsingenieurwesen

Computed tomography has entered the industrial world in 1980’s as a technique for non-destructive testing and has nowadays become a revolutionary tool for dimensional metrology, suitable for actual/nominal comparison and verification of geometrical and dimensional tolerances. This paper evaluates measurement results using different measuring strategies applied in different inspection software packages for volume and surface data analysis. The strategy influence is determined by calculating the measurement uncertainty. This investigation includes measurements of two industrial items, an aluminium pipe connector and a plastic toggle, a hearing aid component. These are measured using a commercial CT scanner. Traceability is transferred using tactile and optical coordinate measuring machines, which are used to produce reference measurements. Results show that measurements of diameter for both parts resulted in smaller systematic errors compared to distance and height measurements. It was found that uncertainties of all measurands evaluated on surface data were generally greater compared to measurements performed on volume data.

Beitrag (Sammelband oder Tagungsband)

Himani Jain, N. Hartmann, V. Buch, P. Serbun, A. Navitski, G. Müller

Electron emission of laser-structured carbon nanowalls on Si and stainless steel substrates

Proceedings of the 2011 24th International Vacuum Nanoelectronics Conference (18-22 July 2011; Wuppertal)

2011

Angewandte Naturwissenschaften und Wirtschaftsingenieurwesen

Beitrag (Sammelband oder Tagungsband)

P. Müller, Jochen Hiller, A. Cantatore, L. Chiffre

Investigation of measuring strategies in computed tomography

Proceedings of the International Conference on Advanced Manufacturing Engineering (Newstech, Brno, Tschechische Republik)

2011

Beitrag (Sammelband oder Tagungsband)

S. Weide, P. Gege, C. Schwarz, M. Bachmann, S. Holzwarth, M. Habermeyer, P. Müller, P. Haschberger, Paul Schötz, K. Lenhard, E. Bogner, T. Schwarzmaier

Flugzeuggetragene hyperspektrale Fernerkundung am Deutschen Zentrum für Luft- und Raumfahrt (DLR)

Vorträge Dreiländertagung - Wissenschaftlich-Technische Jahrestagung der DGPF, 01.-03.07.2010, Wien, Österreich, vol. 19

2010

Beitrag (Sammelband oder Tagungsband)

Peter Hofmann, P. Lohmann, S. Müller

Change Detection by Object-Based Change Indications

Proceedings of the 4th EARSeL Workshop on Remote Sensing for Developing Countries in Conjunction with GISDECO (June 4-7, 2008; Istanbul, Turkey]

2008

Beitrag (Sammelband oder Tagungsband)

C. Heipke, Peter Hofmann, P. Lohmann, S. Müller

Concepts of an Object-Based Change Detection Process Chain for GIS Update

Proceedings of the XXIst ISPRS Congress (July 3-11, 2008; Beijing, China)

2008

Beitrag (Sammelband oder Tagungsband)

P. Lohmann, Peter Hofmann, S. Müller

Updating GIS by object-based change detection

Geoinformatics Paves the Highway to Digital Earth, vol. 8

2008

Nachhaltig Angewandte Naturwissenschaften und Wirtschaftsingenieurwesen TC Teisnach Sensorik

Zeitschriftenartikel

Peter Hofmann, P. Lohmann, S. Müller

Concepts of an object-based change detection process chain for GIS update

International Archives of Photogrammetry and Remote Sensing, vol. 37, pp. 305-312

2008

Zeitschriftenartikel

H. Treichel, Günther Ruhl, P. Ansmann, R. Würl, C. Müller, M. Dietlmeier

Low dielectric constant materials for interlayer dielectric

(Invited Paper)

Microelectronic Engineering, vol. 40, no. 1, pp. 1-19

1998

DOI: 10.1016/S0167-9317(97)00185-8