Real-time Measurement of Electrical Conductivity for Aluminium Wires Using a Novel Calibration Method

This paper presents a strategy for non-contact measurement of the conductivity of Aluminum wires used in wire + arc additive manufacture. A cylindrical electromagnetic sensor consisting of coil pair (an excitation and a receiver coil) is designed and the change in the mutual inductance due to the presence of the wire inside the sensor is measured at multiple frequencies. A novel calibration method is proposed. It was found that the calibrated inductance agrees well with the inductance measured by a commercial instrument. Moreover, the phase of the inductance is linearly related to the conductivity of the wire measured via a contact four-terminal measurement method. This technique can be potentially applied to the real-time in-situ inspection of metal wires by measuring their conductivity variation, which could contribute to the quality control of wire + arc additive manufacture processes.