DigitalF: Maschinenbau und MechatronikI: Fraunhofer AWZ CTMTZeitschriftenartikel
A. Gameros, L. Chiffre, H. Siller, Jochen Hiller, G. Genta
A reverse engineering methodology for nickel alloy turbine blades with internal features
CIRP Journal of Manufacturing Science and Technology, vol. 9, no. May, pp. 116-124
2015
DOI: 10.1016/j.cirpj.2014.12.001
Abstract anzeigen
The scope of this work is to present a reverse engineering (RE) methodology for freeform surfaces, based on a case study of a turbine blade made of Inconel, including the reconstruction of its internal cooling system. The methodology uses an optical scanner and X-ray computed tomography (CT) equipment. Traceability of the measurements was obtained through the use of a Modular Freeform Gage (MFG). An uncertainty budget is presented for both measuring technologies and results show that the RE methodology presented is promising when comparing uncertainty values against common industrial tolerances.
DigitalF: Maschinenbau und MechatronikI: Fraunhofer AWZ CTMTZeitschriftenartikel
P. Müller, Jochen Hiller, Y. Dai, J. Andreasen, H. Hansen, L. Chiffre
Quantitative analysis of scaling error compensation methods in dimensional X-ray computed tomography
CIRP Journal of Manufacturing Science and Technology, vol. 10, no. August, pp. 68-76
2015
DOI: 10.1016/j.cirpj.2015.04.004
Abstract anzeigen
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.
F: Maschinenbau und MechatronikI: Fraunhofer AWZ CTMTZeitschriftenartikel
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
DOI: 10.1016/j.cirpj.2014.04.002
Abstract anzeigen
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.
F: Maschinenbau und MechatronikI: Fraunhofer AWZ CTMTZeitschriftenartikel
Jochen Hiller, G. Genta, G. Barbato, L. Chiffre, R. Levi
Measurement Uncertainty Evaluation in Dimensional X-ray Computed Tomography Using the Bootstrap Method
International Journal of Precision Engineering and Manufacturing, vol. 15, no. 4, pp. 617-622
2014
DOI: 10.1007/s12541-014-0379-9
Abstract anzeigen
Industrial applications of computed tomography (CT) for dimensional metrology on various components are fast increasing, owing to a number of favorable properties such as capability of non-destructive internal measurements. Uncertainty evaluation is however more complex than in conventional measurement processes, e.g., with tactile systems, also due to factors related to systematic errors, mainly caused by specific CT image characteristics. In this paper we propose a simulation-based framework for measurement uncertainty evaluation in dimensional CT using the bootstrap method. In a case study the problem concerning measurement uncertainties was addressed with bootstrap and successfully applied to ball-bar CT measurements. Results obtained enabled extension to more complex shapes such as actual industrial components as we show by tests on a hollow cylinder workpiece.
F: Maschinenbau und MechatronikI: Fraunhofer AWZ CTMTZeitschriftenartikel
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
DOI: 10.1016/j.procir.2013.08.022
Abstract anzeigen
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.
F: Maschinenbau und MechatronikI: Fraunhofer AWZ CTMTZeitschriftenartikel
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
DOI: 10.1051/ijmqe/2012011
Abstract anzeigen
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.
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