High-Speed Inline Production Testing of Cast Pistons Using 3D-CT and a Digital X-Ray Detector 2013-01-1426

Weight and heat management of performance aluminum alloy pistons leads to complex piston designs that can be difficult to manufacture compared to conventional pistons. In order to verify the casting quality and detect pores, cracks and other defects, the use of X-ray testing methods is inevitable.

While automatic 2D X-ray image processing has become a standard quality control method for simple cast parts, 3D volume processing is not yet widely used. The main reason is usually not the cost difference between 2D and 3D X-ray, but rather the processing time required for image acquisition. Compared to often only a few images required to cover a part using 2D X-ray images, a CT reconstruction requires a large number of images to minimize reconstruction artifacts. Since each image requires a certain minimum exposure time to minimize image noise, the total time for object handling, image acquisition, volume reconstruction and finally automatic volume processing is often beyond the throughput required for mass volume application.

This paper describes a system using PC hardware and a new kind of digital X-ray detector to perform image acquisition, reconstruction and evaluation of lightweight alloy cast pistons keeping pace with production. The paper will present the system concept, sample data and the experiences gained during the development of this system.