Jinyi Lee
The Journal of Mechanical Science and Technology, vol. 22, no. 12, pp.2310-2317, 2008

Abstract : Magnetic flux leakage testing (MFLT), which measures the distribution of a magnetic field on a magnetized specimen by using a magnetic sensor such as a Hall sensor, is an effective nondestructive testing (NDT) method for detecting surface cracks on magnetized ferromagnetic materials. A scan-type magnetic camera, based on the principle of MFLT, uses an inclined Hall sensor array on a printed circuit board (PCB) to detect small cracks at high speed. However, the wave forms appear in a direction perpendicular to the scan because the sensors are bonded at different gradients and heights on the PCB despite careful soldering. In this paper, we propose linearly integrated Hall sensors (LIHaS) on a wafer to minimize these waves and to improve the probability of crack detection. A billet specimen is used to determine the effectiveness of the LIHaS in multiple crack detection.

Keyword : Magnetic camera; Sensor array; Ferromagnetic; Crack; NDT