Experimental Low-Cost Magnetic Scanning for Non-Destructive Testing With Hall Sensors: Determining Material’s Thickness

Abstract

Non-destructive testing (NDT) is a highly regarded area on the medical, space and defense sectors but, also on heavy equipment susceptible to corrosion and hidden structural defects. One of the mature NDT methods for steel structures is magnetic flux leakage (MFL) detection. The current technique implementations require expensive equipment, specialist knowledge and custom data analysis tools whereas, the method uses large strong magnets on the same plane with the sensor while rolling on the inspected area, exerting a high pressure due to its magnets’ attraction and heavy body system, making it suitable only for a reduced number of investigation scenarios. This work experimentally investigates a complementary setup to classical MFL approach, useful for detection of a thin steel thickness variations from 0.7 mm up to 3.5 mm, while using a light low cost Hall sensor array setup built with accessible off-the-shelf components. Instead of the horseshoe magnet moved simultaneously with the detectors, this work uses small strong magnets tiled together and static as referred to the sensor array’s scanning movement. In this way, analyzing the sensor behavior at different spatial points in the complex magnetic field resulted from the low cost setup, this study delivers high valuable insights for MFL research.