The feasibility of using planar microfabricated eddy-current sensors for non-destructive testing of varying levels of grinding burn is presented. A 42CrMo4 workpiece is ground with varying degree of grinding burn as a test reference for the development of micro eddy-current sensors. Planar non-spiral and spiral micro-coils geometries are fabricated using electrochemically deposited nickel-cobalt alloys.The presence of grinding burn, perceived as a change in the relative permeability in the grinding zone, is exploited by the eddy-current sensor for its detection. The inductance of 20 turns micro-coil with non-spiral and spiral geometry was found to be 0.22 µH and 1.5 µH, respectively. The impedance response of the micro-coils changed with the degree of grinding burn and the impedance difference increased with frequency. The impedance of spiral µcoil increased by ca. 3% on moving it from low degree of grinding burn to high degree of grinding burn, which was found to be 10 times more than that of non-spiral µcoils.
Track ID:
6
Track Name:
Physical Sensors: Temperature, Mechanical, Magnetic and Others
