OPTIMAL FREQUENCY DESIGN OF EDDY CURRENT TESTING FOR COPPER, BRASS AND MAGNESIUM ALLOY METAL WITH DIFFERENCE THICKNESS

Abstract

The main objective of this paper is to find the optimisation frequency for a designed non-destructive testing (NDT) metal instrument known as eddy current testing (ECT). The chosen materials were copper (Cu), brass and magnesium alloy (Mg) metals in 100 mm X 100 mm dimension, and with different type of thickness, i.e. 1.5 mm, 3 mm and 5 mm. All of the three (3) different kind of thicknesses in each metal were installed with artificial defect and were tested to identify the optimal frequency. A dual-sensors were designed and established to gather the voltage output with input frequencies were ranged between 250 kHz - 3.5 MHz. The output signals of the voltage of testing from the sensor circuit then compared to analyse the optimal of range frequency for the testing instrument. The result of this research showed that the non-destructive metal testing instrument of dual-sensors by using ECT method can be used to find different defect for these metals, i.e. copper (Cu), brass and magnesium alloy (Mg). The optimal frequencies for copper was 2.95 ????????????, brass was 2.90 ???????????? and magnesium was 2.89 ????????????. The categorisation of thickness on metal for the ECT instrument is suitable at 2.95 ???????????? for copper, 2.90 ???????????? for brass and 2.89 ???????????? for magnesium alloy, which also known as the optimal frequency.