Rod shape testing by high frequency eddy current

Methods of red-hot rod shape testing require a robust non-contact measurement principle as a touch point could lead to damages at the rod and the detection unit. Therefore a new basic approach based on high frequency eddy current has been investigated. Due to the robustness and the ability to determine the rod shape even above the Curie temperature this principle is especially well suited and could be implemented in the production process directly. The first automatic measurement setup was successfully developed with promising results. Hereby a defect of ovality was detected with a parallel LC-oscillator. The capacity of this LC-oscillator is constant whereas the inductance is the measurement part and varies due to eddy current interactions with the rod.