High-speed inspection of rails using ACFM techniques

High-speed ACFM tests were carried out using a rotary test piece that contained spark-eroded notches. The ACFM sensor detected the induced notches during inspection at 121.5 km/h. The recorded signal remained unaffected by the increases in inspection speed under constant lift-off. To simulate actual rail inspection conditions at high speed, further tests were carried out using a spinning rail rig and a set of rails that contained spark-eroded notches of various shapes and sizes up to a speed of 32 km/h. Although, the ACFM sensor successfully detected the majority of the notches, the signal obtained was affected by lift-off variations.