Eddy Current Testing Technique to Detect Imperfection Surface for Different Lift-off Value on Copper Metal

Non-Destructive Testing (NDT) known as the evaluation of properties of a wide variety of materials without causing a damaged despite after inspection is done and the material still can be used. This paper aims for a designed NDT metal instrument that is conducted using eddy current testing (ECT) technique to find an applicable lift-off (LO) value in detecting imperfection. A dual sensor was designed consist of excitation coil was applied to evaluate the surface imperfections or other excitation frequencies in controlling the signal responses from the testing material, copper (Cu) with dimension of 100 mm x 100 mm installed with artificial surface imperfection (i.e., 7 mm, 14 mm and 21 mm) was main subject in this study. An established amplifier consisting of a specific op-amp was used to boost up the voltage of the alternate current (AC). The data of setting frequencies was ranged from 5.00 - 5.25 MHz was recorded varied of the LO values (i.e., 1.0 mm, 2.0 mm, 3.0 mm, 4.0 mm and 5.0 mm). Based on the frequencies applied the result for an applicable LO value acquires the promising result of reading signal was around 2 mm and the imperfection detection performance obtained a larger voltage gradient with the increase of the imperfection sizes. The study concludes that the developed non-destructive metal testing instrument of specific ECT design by using the excitation coil is appropriate in measuring the LO value and could be used to find different imperfection for metal

Maximum distance of lift-off height to detect defect on testing materials by using eddy current testing technique

Eddy Current Testing (ECT) technique is one of the Non-Destructive Testing (NDT) techniques that is sensitive to the unintended signal such as the lift-off (LO) effect. For ECT technique, LO effect is one of the constraints due to the weakened detection that affected the output of the signals. This presented research aims to develop coil probe that generates eddy current signals from an ECT technique in order to determine the optimum signal distance of LO height for three different chosen materials (e.g., copper, brass, and magnesium alloy) of three (3) different thickness which are 1.5 mm, 3.0 mm and 5.0 mm each. The output voltage of the defects signal of the tested materials can be determined from the optimum signal distance of LO height of the ECT technique. The coil probe used consists of an exciter-receiver coil, where 5.25 MHz is the optimal frequency. This frequency then generates the signal of the ECT technique. This technique was set up using a 50 ohms function generator and an established amplifier to boost up the output signals. The acquired optimum distance LO height for this research is approximately 2 mm. The findings from this established technique indicate the determined LO height can be used to find the output voltage signal of the defects as well as to detect the thicknesses. The output voltage signal from the ECT technique was analyzed and compared. In a conclusion, the output voltage signals slightly increased for larger material defects and subsequently decreased with greater thickness detection. Hence, the lift-off height parameters of the ECT technique in this research is capable to detect defect appropriately

The Optimum Distance of Lift-Off Height on Different Test Material’s Thickness by using Eddy Current Testing Technique

The Eddy current testing (ECT) technique is one of the non-destructive testing (NDT) techniques which is sensitive to the unintended signal such as lift-off (LO) height effect. The output voltage of signal defects with different thicknesses of test materials (i.e., Copper, Brass and Magnesium Alloy) can be determined from the optimum distance of LO height of the ECT technique. Previously, an established frequency was determined for these particular materials (i.e., Copper = (5.00-5.25) MHz, Brass = (4.75-5.25)MHz and Magnesium Alloy= (4.75-5.00)MHz). The frequency then generated the established voltage signal of the ECT technique. The acquired optimum distance of LO height for these materials is approximately 2mm. The findings from this established technique indicated that the determined optimum distance of LO height can find the output voltage signal of the defects as well as to detect the thicknesses