Robotic welding of aluminium alloys

• Main Author: Ooi, Tzyy Yih
• Other Authors: Zhou Wei
• Format: Final Year Project
• Language: English
• Published: Nanyang Technological University 2020
• Subjects: Engineering::Mechanical engineering::Robots; Engineering::Materials::Testing of materials; Engineering::Manufacturing
• Online Access: https://hdl.handle.net/10356/137081
• Institution: Nanyang Technological University

5083 aluminium alloy is a widely used material in modern engineering applications. Metal inert gas robotic welding is commonly used to perform mass joining of metals like 5083 aluminium alloy. Electric current from metal inert gas welding generates localized electromagnetic field. Magnetic assisted welding can be used to generate Lorentz force to control the welding arc with variable current and frequency. Controlling the welding arc can influence the transfer of weld droplets and molten pool during welding. Hence, it is essential to study how changing the frequency of the magnet affects the microstructure of the weld. With this understanding, it is then possible how to use magnetic frequencies to optimize the reliability and quality of the weld when using magnetic assisted welding. In this project, electromagnetic field assisted robotic metal inert gas welding is conducted to study the effect of frequency on microstructure and microhardness of 5083 aluminium alloy. Metallographic sample preparation was performed on five specimens for microscopic analysis using stereomicroscope, optical microscope and scanning electron microscope. Under the influence of electromagnetic field frequency, the welds generally have better wettability and flowability, which improves the weld quality. On the other hand, if the influence of the electromagnetic field is weak, the welding process is not stable, leading to the unstable movement of the weld droplets and molten pool. This introduces more porosity in the fusion zone and weld spatters. This reduces the quality of the weld. Vickers microhardness test was also performed. The hardness of the weld is lower as the frequency of the electromagnetic field increases. The range of hardness of the weld also narrowed down as EMF frequency increases. From the measurements across the weld, under the influence of magnetic frequency, the decrease in hardness is not significant. The average hardness is decreased from 7.67% to 9.92% when compared to that of the without influence of magnetic frequency. As from the measurements vertically down the centre of the weld, under the influence of EMF frequency, the decrease in average hardness is less significant. It is from -0.16% to 6.20%.