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2006
Conference Paper
Titel
High-speed, high-resolution magnetic flux leakage inspection of large flat surfaces
Abstract
Magnetic Flux leakage (MFL) inspection of flat surfaces can be done by scanning the areas of interest with magnetoresistive or Hall effect sensors. However, most applications require short measuring times which may not be achieved by scanning the area of interest with a single sensor. The common solution to this problem is the use of sensor arrays in the shape of a straight line or a matrix of elements. However, the local resolution is then limited by the sensor spacing within the line or matrix. Due to the scattering of sensor properties, accurate procedures for calibration or compensation are required in order to adjust the array to a homogeneous sensitivity and offset. This task is of particular importance when longterm changes and temperature dependence of the sensor properties have to be taken into consideration. This paper discusses a new approach to MFL testing of flat surfaces which reaches high speed and high local resolution with a small amount of sensors and implicitly compensates for different sensor properties during the measurement. Thereby, a quick inspection of even meter- to kilometer-sized surfaces becomes possible with local resolutions of 1 cm² and below. As a side-effect, reduced production costs may be obtained as compared to the costs of a sensor array of same resolution and accuracy.
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