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Dilok Klaisataporn
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White-Light Scanning for In-Line Product Quality Verification

April 5, 2012
As the value of cast parts increases, the importance of quality assurance rises and the technology deployed to measure quality advances. In turbine blade production, for example, interferometers are deployed to verify the shape and surface texture of obje
A new Breuckmann scanning systems line is stereoSCAN3D, which works in green light in order to adjust the 3D data acquisition process to customers’ project requirements. The 8.0-megapixel Ethernet cameras used for this method make data collection even faster and, reportedly, generate more true-to-detail 3D data.

White-light scanning quickly evaluates numerous geometrical parameters of a turbine blade, e.g., concave/convex contour, thickness, chord, twist/warp/ stagger, platform, and bow. Also evaluated are parameters like lean and centrality, center of gravity, contour of leading edge and trailing edge, or the complete blade contour.

White-light scanning is one of various interferometric methods finding a place in highvolume product inspection, initially because of the process speed. For example, to inspect just one turbine blade a coordinate measuring machine may require up to an hour to gather all the necessary parameters. Breuckmann GmbH indicates its new white-light scanning package, the b-INSPECT3D system, is able to capture entire object geometries quickly, without preparatory steps, like spraying or matting.

Breuckmann develops optical systems for contact-free measurement, digitization, and 3D inspection. It states that a patented fringe-projection technique is the basis of its 3D digitization and measuring systems, characterized by fast data acquisition and high-level adherence to detail for complex surface geometries.

b-INSPECT3D is based on an adapted structured light projector working with customized software. The measuring chamber is easily accessible for positioning the blades for measurement, and for system maintenance. A sturdy turn/tilt unit allows complete data acquisition from angles or areas that are difficult to access; in order for objects to be automatically placed into position for measuring, the station can be equipped with a six-axis robot. The system is shielded against dust to ensure precise data acquisition even in plant-floor settings.

For automated 3D data acquisition of very small objects, Breuckmann developed the INSPECT3D-II as a two-camera system, equipped with high-power LED lights. The developer noted this new design provides 10 times more light intensity, which improves edge definition significantly. Together with the speed-optimized data acquisition and evaluation, users will collect more data, more quickly.

Thanks to the system’s housing, digitization is insulated from interference. The data that’s generated is in STL format and can be used for further processing by any CAD or inspection software. Combining a robot and a turn/tilt unit to position the object being inspected makes INSPECT3D scanning fully automatic, as well as reliable, for volume production and/ or serial inspection procedures. The installation offers various evaluation and reporting options, from target-versus- actual-comparison up to the analysis of specific blade parameters (e.g. maximum thickness, chord length.) Finally, the back projection option for identified deviations onto the measuring object simplifies interpretation of the results.

In particular for inspecting objects with sharp edges, as well as the small radii of leading and trailing edges that are critical to turbine blade performance, the b-INSPECT3D helps to verify quality in ways that other surface-area measuring systems cannot achieve: The complete blade edge is captured very quickly and with high precision; and the measuring data is not restricted to individual cuts.

Breuckmann emphasized its sensor technology is flexible, modular, and accurate enough to be adapted for reverse engineering, product design, and process optimization, as well as quality control.