Aluminum and aluminum alloys are the most widely used nonferrous metal materials in the manufacturing industry at present, and have a large number of applications in heavy industry manufacturing, decoration and building materials, food machinery, marine machinery, and new energy power batteries.
 

At the same time, due to the large differences in the welding performance of different series of aluminum alloys, the welding is difficult, which has become the bottleneck of its further development. In order to solve these difficulties, more and more technical personnel have been involved in the research of this field, and new technologies and processes have been introduced, providing more possibilities for the further development of aluminum alloy applications.

The reason why the welding of aluminum and aluminum alloy is difficult is mainly because of its own performance. The composition of aluminum alloys is complex. Except for a series of industrial pure aluminum, other series of aluminum alloys are doped with a large number of other metal and non-metallic components. The physical and chemical properties of these metal and non-metallic elements are quite different from that of aluminum itself, and welding defects such as pores, cracks and poor mechanical properties outside the weld are prone to occur during the welding process. For laser welding, aluminum and aluminum alloy dry high reflective materials, how to improve their laser absorption and prevent reflective damage to the laser has become an urgent problem to be solved. In view of the welding difficulties of aluminum alloy, major laser manufacturers and integrators have also introduced various ways to solve them in their respective fields.

1、 Laser cutter's improvement

Anti-hyperreflexes

Aluminum and aluminum alloy materials are highly reflective materials. The absorption rate of 1080nm laser is not high, which affects the stability of the processing process. Especially in the welding process, there will be a higher return phenomenon, often because of the high reflection, the laser life will be reduced, and even the pump source will be burned. In recent years, various laser manufacturers have invested a lot of energy to solve this problem, starting from the internal shutter, installing the return light isolator, and starting from the QBH head, stripping the return light from the source. At present, these solutions have achieved good practical results. From this point, the future can be expected.

Adjustable beam

All laser manufacturers have introduced beam adjustable technology starting from the beam. By adjusting the beam mode, a larger and more stable keyhole is produced. The annular beam softens the material and deflects towards the bottom of the molten pool, reducing welding spatter and porosity, effectively improving the welding quality and efficiency of aluminum alloy materials.

Blue laser

Due to the poor absorption of high reflective materials such as copper and aluminum on the infrared band, a large amount of spatter will be generated during laser welding, so the parts have to be cleaned after welding. However, compared with the infrared band, the copper and aluminum material has a higher absorption of blue light, almost ten times of the infrared band. Blue laser can be connected at a lower power and maintain the cleanness of welding. Therefore, laser manufacturers have also launched blue laser to the market.

2、 Welding process improvement

While laser manufacturers solve problems from the beam side, many laser welding integrators have also launched their processes to face the market.

Swing welding
The swing welding mode refers to the use of the special laser swing welding head to swing the beam, so that the beam processing range is enlarged, the weld width has a better tolerance, and the welding quality is improved.

Dual-wavelength laser welding

When the composite light source is used to weld metal materials, the main light source optical fiber laser carries out deep penetration welding for the base metal. The semiconductor laser acts as a sub-band light source to synchronously preheat the material and increase the time of its melting state, which helps to suppress the generation of welding hot cracks and internal pores in the welding, while improving the stability of the welding holes. In addition, semiconductor laser can greatly increase the absorptivity of the base metal to the laser, and has great advantages in the welding of high-reflective materials such as copper and aluminum.

Laser-MIG hybrid welding

For the welding of dry aluminum alloy thick plates, it is difficult to achieve the desired effect by using a single laser as the heat source. At present, industrial enterprises basically adopt the traditional arc welding method, which requires beveling, multi-layer and multi-pass welding. The production efficiency is low, the working intensity is large, and the welding deformation is large. It is difficult to ensure the weld quality. Laser-MIG composite welding has the characteristics of large welding penetration and welding strength. Single laser welding is sensitive to the requirements of product gap and position due to the small welding spot and the consideration of power device, while laser-MIG composite welding has a very good tolerance when the gap and position error are within 1.6mm, which reduces the requirements of assembly accuracy and production cost. At the same time, the mutual cooperation between laser and arc has also achieved mutual benefit. The laser plays a stable role in the arc by compressing the arc, and can maintain a stable arc state even under the high-speed welding state. The arc also promotes the absorption of laser energy, and can obtain deeper penetration under the same power. At the same time, the deformation of locust grafting can be reduced by up to 60%, saving 80% of the time. 

With the gradual increase of output power, high-power laser-MIG hybrid welding will also be applied to more and thicker products.

More and more solutions have overcome the welding difficulties of aluminum alloy, but no welding method is perfect and universal. For different welding needs, the future development must be diversified and personalized. How far is the perfect welding of aluminum alloy? At present, there is no answer. Every technological progress requires continuous exploration by laser welding practitioners.

About HGTECH: HGTECH is the pioneer and leader of laser industrial application in China, and the authoritative provider of global laser processing solutions. We have comprehensively arranged laser intelligent machine, measurement and automation production lines, and smart factory construction to provide overall solutions for intelligent manufacturing.