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18th World Conference on Nondestructive Testing, 16-20 April 2012, Durban, South Africa

Fully-Automated 3D Metrology and Defect Analysis with High-Resolution

300 kV Microfocus Computed Tomography

Oliver Brunke

Product Manager for 3D Metrology and Failure Analysis using Computer Tomography, GE Sensing &

Inspection Technologies GmbH, 31515 Wunstorf, Germany; Phone: +49 5031 172 142, E-mail:

oliver.brunke@ge.com, www.ge-mcs.com/phoenix

Abstract

With industrial X-ray computed tomography (CT), even low-contrast defects in cast parts, such as cracks, pores

and blowholes, can be localized and measured in three dimensions. Analysis of the defects can be performed

using either multi-positional 2D cross-section planes or the 3D volume view. Additionally, 3D metrology with

CT becomes more and more an effective tool for many tasks in production process monitoring such as the

manufacture of plastics, metal castings and precision components like injection nozzles. Particularly complex part

geometries with inaccessible or hidden features can be measured with CT in many cases faster than with

conventional Coordinate Measuring Machines (CMMs). This paper shows failure analysis and metrology tasks

automatically performed on a new GE CT system optimized for stable and reproducible CT scans and equipped

with a new unipolar 300 kV microfocus X-ray tube, new CT software for fully automated data acquisition,

volume processing and 3D evaluation capability.

Keywords: 3D Metrology, automated Computed Tomography, CT, µCT, CMM

1. Introduction

Complete 3D mapping means that CT can also be used for the non-destructive 3D

measurement of cast parts that cannot be inspected using conventional coordinate measuring

machines due to their complex internal geometry. Therefore, CT has numerous practical uses

in addition to non-destructive quality control; for instance, it can be used for optimizing and

reducing the time required for development and initial sampling processes, comparing

components with the target CAD model or reverse engineering in which 3D component data is

used to construct a three-dimensional CAD model (fig 1). Fully automated scanning and

analysis processes mean that the creation of first-article inspection reports, even for complex

components, is possible in less than one hour.

Fig. 1: Reverse engineering, automatic pore analysis and 3D metrology of a scanned automotive control arm

2. Advanced CT Technology

Summary of content (6 pages)

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8th World Conference on Nondestructive Testing, 16-20 April 2012, Durban, South Africa Fully-Automated 3D Metrology and Defect Analysis with High-Resolution 300 kV Microfocus Computed Tomography Oliver Brunke1 1 Product Manager for 3D Metrology and Failure Analysis using Computer Tomography, GE Sensing & Inspection Technologies GmbH, 31515 Wunstorf, Germany; Phone: +49 5031 172 142, E-mail: oliver.brunke@ge.com, www.ge-mcs.
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The new phoenix v|tome|x m of GE Inspection Technologies is the industry’s first compact 300 kV CT system for 3D metrology and failure analysis with less than 1µm detail detectability, suitable for 500 x 600 mm samples with a field-of-view up to 300 mm diameter and 400 mm in height and up to 50 kg in weight. The system offers excellent magnification and resolution for high-absorbing metal samples.
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Fig. 3: Automatic porosity analysis of an automotive casting. The distribution of differently sized pores within the entire cast part can be shown in different colours. 4. High-Resolution CT-Based 3D Metrology Due to the large number of internal contours in cast parts made from plastic or light alloys, the use of conventional measurement methods to inspect such parts is often not possible in a nondestructive way and takes a considerable amount of time.
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The precision of the measured raw data (CT projection data) determines the accuracy of all subsequent evaluations. In addition to a stable system structure that is optimized for the specific application at hand, data processing is the key to successful CT-based measurement. For optimal measurement results, therefore, the reconstruction algorithm used to calculate the volume data has to take into account and correct the unavoidable physical effects of CT scanning, such as 'beam hardening'.
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Fig. 5: Nom. /act. comparison and evaluation of three dimensional parameters on a scanned cylinder head. 6. Fully Automated Data Acquisition and Volume Processing With GE’s advanced phoenix datos|x CT software, the entire CT chain described above can be fully automated.
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length variance is ≤6 µm. Parameter Target CAD Tolerance Actual CT Actual CMM CT/CMM variance Ø Z 1 [mm] 28.000 0.050 28.035 28.034 0.001 Distance A 1 [mm] 70.500 0.100 70.442 70.447 -0.005 Table 1: Excellent correspondence between the measurement data from the 3D coordinate measuring machine and high-resolution computed tomography 8.