Research and Application on MIG Welding Process of Aluminum Alloy
Abstract
The fusion welding process of aluminum alloy has always been a major challenge for welding technology due to its high thermal reflectivity and high thermal conductivity. In order to overcome the problems of aluminum alloy fusion welding, in this paper, a kind of fusion welding process named Metal Inert Gas (MIG) welding is discussed for application in aluminum alloy fusion welding. This paper elaborates on the principles and classification of MIG welding, and then introduces the performance of the MIG welding, its characteristics and its application in aluminum alloy fusion welding. Finally, some measures to improve the welding quality and avoid welding defects are analyzed. The application of MIG welding in aluminum alloy fusion welding can realize stable and reliable welding, which can improve welding speed and reduce welding costs.
Key words: aluminum alloy; MIG welding; performance; welding defects
1 Introduction
Aluminum alloy is a kind of material with high thermal reflectivity: when aluminum alloy comes into contact with the external environment, its surface temperature tends to be affected by the external environment temperature, leading to defective or even failure welding process. In addition, the microstructure of the aluminum alloy makes it incompatible with the traditional welding method using manual welding or CO2 welding rod. Moreover, the high thermal conductivity of the aluminum alloy will diminish the molten material easily, forming small molten pool and affecting the quality of the fusion welding. Therefore, the welding process of aluminum alloy is faced with many challenges. In order to overcome the problems of aluminum alloy welding and produce high quality products, Metal Inert Gas (MIG) welding needs to be applied.
2 Theory of MIG Welding
MIG welding technology is a metal protective gas welding process, also named GMAW (Gas metal arc welding), one of the most widely used welding process. In MIG welding process, a wire electrode is used as the welding material, and the metal wire electrode is fed into the welding arc by a welding machine, forming a molten pool and finally realizing the welding of the two pieces of aluminum alloy parts. The protective gas is mainly for a protective covering on the surface of the molten pool and the welded joint during welding to reduce spatter, avoid oxidation and ensure the arc stability. In the MIG welding process, the voltage and current is automatically adjusted according to the factors such as the diameter of the wire, gas flow and distance between the wire and the joint to realize the welding of aluminum alloy.
3 Classification of MIG Welding
The MIG welding process can be divided into three categories according to the purpose of the welding and construction conditions. The first is short-circuit transfer welding. It is suitable for small workpieces and thin plates, with simple welding conditions such as small current and low welding speed. The second one is droplet transfer welding. This welding mode is suitable for the welding of various thicknesses of aluminum alloy plates, with large current and instantaneous transfer of melting wire droplets from the electrodes to the weld zone through arc. The third is spray transfer welding which can be applied to welding of aluminum alloy workpieces with large thickness and high output welding parameters.
4 Performance of MIG Welding
MIG welding has many advantages compared with other welding processes, such as high welding speed, large deposition efficiency, good welding quality and little welding spatter. It can be used for welding of aluminum alloys with low melting point and wide application.
Benefits: Compared with CO2 welding and manual arc welding, the advantages of MIG welding are more prominent. For example, because of its high deposition efficiency, it can reduce welding time, improve welding quality and stability, reduce welding defects and save cost. In addition, its welding speed is fast and the welding seam is smooth and beautiful, which can bring convenience to the production.
5 Characteristics of MIG Welding
The characteristics of the MIG welding are mainly reflected in the protection gas. Compared with the traditional argon arc welding and manual argon arc welding, the MIG welding has a more stable arc, resulting in better protective effect of the MIG welding.
In MIG welding process, the welders can easily adjust and adjust the current and voltage according to the welding conditions. In addition, since the arc of the MIG welding has good stability and the shielding gas supply is convenient and flexible, the welders can adjust the parameters of the electrode and the nozzle according to the welding length and the welding requirements, so as to obtain higher welding quality and higher welding efficiency.
6 Application in Aluminum Alloy Fusion Welding
MIG welding has been widely used in aluminum alloy fusion welding. In the MIG welding process, the welding wire is directly used as the melting material. It not only increases the welding speed, but also increases the flexibility of the welding process, so that it is convenient to apply in large and small aluminum alloy components.
Moreover, due to the high stability of the arc, the MIG welding also can extend the length of the arc and improve the electrical energy utilization rate. In addition, with the increase of the welding speed, it is also possible to suppress the increase of the heat input, control the welding deformation, and reduce the holes in the welding.
7 Measures to Improve Welding Quality
As MIG welding is applied in aluminum alloy fusion welding, it is necessary to take many measures to improve the welding quality and reduce welding defects. Here are some measures taken to ensure the welding quality.
a) Choose proper welding parameters for MIG welding of aluminum alloy: The welding parameters, such as current, voltage, wire feeding speed and arc voltage, should be properly selected according to the welding requirements to ensure the best welding quality.
b) Choose the appropriate welding gun and nozzle: The suitable welding gun and nozzle will reduce the arc fluctuations, improve the welding quality and reduce the welding spatter.
c) Make sure the environment is dry and clean: Moisture, oil, dust and other atoms can affect the stability and cleanness of welding, resulting in welding defects.
d) Use rust-proof wire as welding material: The use of rust-proof wire can reduce the entrance of moisture on the weld surface, thus improving the welding quality.
e) Avoid too much welding heat: Too much welding heat will cause weld pool to overheat, resulting in the decrease of the weld strength and weld penetration, so the heat input must be controlled at the welding process.
8 Conclusion
MIG welding can be used to weld aluminum alloy and aluminum alloy components, which not only has high welding speed, but also has high welding quality and no spatter. In order to ensure the welding quality, it is necessary to correctly select the parameters and welding materials, keep the environment clean and dry, avoid too much welding heat etc. Finally, the application of MIG welding in aluminum alloy fusion welding can realize stable and reliable welding, improve welding speed and reduce welding costs.
