Matters Needing Attention When Welding Aluminum Alloy With Laser Welding Machine!

Fly laser welding machine can weld aluminum and aluminum alloy materials. It has the advantages of high energy density and high welding speed, which provides great convenience for welding aluminum and aluminum alloy materials. If aluminum and aluminum alloy products or accessories are to be welded firmly and have beautiful weld seams, laser welding machines are indispensable for their assistance. Although the effect of laser welding machine welding aluminum and aluminum alloy is good, it still cannot avoid the shortcomings of the welding material itself (high reflection of aluminum and aluminum alloy, low attraction rate, etc.), which increases the difficulty of laser welding, so There are still several aspects to pay attention to when laser welding.

When laser welding aluminum alloy, light reflection phenomenon will appear on the surface of aluminum alloy, because aluminum alloy is a kind of non-ferrous metal, which has strong reflectivity to all kinds of light, so before welding aluminum alloy material, it is necessary to Clean the surface of the alloy to clean up the oil or other stains on the surface. Not only that, but also the oxide film on the metal surface should be cleaned to prevent accidents such as explosions caused by oxidation during the welding process.

Cleaning before welding: When welding aluminum and aluminum alloys, the oxide film and oil stains on the welding joints of the workpiece and the surface of the welding wire should be strictly removed before welding;
1. Chemical cleaning: chemical cleaning has high efficiency and stable quality, and is suitable for cleaning welding wire and small-sized workpieces produced in batches. There are two methods of dipping and scrubbing. Use acetone, gasoline, kerosene and other organic solvents to degrease the surface, wash with 5% to 10% NaOH solution at 40°C to 70°C for 3min to 7min (the time for pure aluminum is slightly longer but not more than 20min), rinse with running water, and then use Pickle with 30% HNO3 solution from room temperature to 60°C for 1min to 3min, rinse with flowing water, and air dry or dry at low temperature.

2. Mechanical cleaning: When the workpiece size is large, the production cycle is long, and it is contaminated after multi-layer welding or chemical cleaning, mechanical cleaning is often used. First wipe the surface with acetone, gasoline and other organic solvents to remove oil, and then directly brush it with a copper wire brush or stainless steel wire brush with a diameter of 0.15mm to 0.2mm until the metallic luster is exposed. Generally, it is not suitable to use grinding wheels or ordinary sandpaper for grinding, so as to avoid sand grains remaining on the metal surface and entering the molten pool during welding to produce defects such as slag inclusions. In addition, scrapers, files, etc. can also be used to clean the surface to be welded. After cleaning, if the storage time is too long (such as more than 24h), it should be reprocessed.

3. Backing plate: The strength of aluminum alloy is very low at high temperature, and the fluidity of liquid aluminum is good. The weld metal is prone to slump during welding. In order to ensure penetration without collapsing, backing plates are often used in welding to support the molten pool and nearby metals. The backing plate can be made of graphite plate, stainless steel plate, carbon steel plate, copper plate or copper rod, etc. An arc-shaped groove is opened on the surface of the backing plate to ensure that the reverse side of the weld is formed. One-sided welding and double-sided molding can also be done without a backing plate, but it requires skilled welding operations or advanced technological measures such as strict automatic feedback control of arc welding energy.
4. Preheating before welding: Generally, thin and small aluminum parts do not need to be preheated. When the thickness is 10mm~15mm, preheating before welding can be carried out. According to different types of aluminum alloys, the preheating temperature can be 100℃~200℃, and oxygen-acetylene can be used. flame, electric furnace or blowtorch, etc. Preheating can reduce the deformation of the weldment and reduce defects such as pores.

Therefore, when laser welding aluminum alloy, it is necessary to strictly pay attention to and rapidly increase the power density of the laser to prevent it from being reflected or transmitted.

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