Laser welding of highly active materials aluminum and copper precautions

High-reflectivity materials reflect a significant portion of the incident light, absorbing relatively little energy. Common high-reflectivity metallic materials include aluminum, copper, gold, and silver. Because of these reflective properties, laser welding of highly active materials like aluminum and copper presents unique challenges.

Some high-reflectivity materials can reflect as much as 80%-90% of the laser energy. When laser welding of highly active materials, only a small portion of the energy is absorbed, so extra care is required during the process. This is why understanding the nuances of laser welding of highly active materials is crucial.

What problems arise when hand-held laser welding high-reflectivity materials such as aluminum and copper? Let’s explore some of the key challenges in laser welding of highly active materials.

Challenges in Laser Welding High-Reflectivity Materials

• Challenge 1: High Energy Density Requirement: The higher reflectivity and very high thermal conductivity of aluminum and copper require a higher energy density for effective laser welding of highly active materials.
• Challenge 2: Porosity Issues: Some aluminum alloys contain volatile elements such as silicon and magnesium, which can lead to more pores in the weld seam. Dealing with porosity is a critical aspect of laser welding of highly active materials.
• Challenge 3: Wire Feeding Difficulties: Aluminum welding wire is relatively soft, making it prone to blockages during the wire feeding process. Proper wire feeding techniques are essential for successful laser welding of highly active materials.

To address these issues in laser welding of highly active materials, pay attention to the following considerations:

1.Focal Length:

• Hand-held laser welding of highly active materials typically uses positive focal point welding.
• Avoid selecting positions outside the focal point and negative focal points because the laser energy is mainly concentrated at the center of the focal point. The focal point is on the surface of the workpiece or inside the workpiece. A high laser power density inside the molten pool easily causes welding spatter, resulting in a rough and uneven weld surface.

2.Shielding Gas Selection:

• The shielding gas for welding is usually an inert gas, argon, with a purity of 99.99% or no less than 99.9%.
• A gas flow rate of 15-20L/min is appropriate. The higher the power, the higher the gas pressure.

3.Workpiece Grinding Treatment:

• Moisture, rust, oil, and other contaminants on the surface of the workpiece will release gas after entering the molten pool. When the molten pool solidifies rapidly, the gas will not be able to escape and form pores. Therefore, the workpiece must be cleaned before welding to remove oil and oxide film from the surface of the weld seam on both sides of the workpiece within a range of 20mm. Thorough surface preparation is vital for laser welding of highly active materials.

4.Welding Wire Selection:

• We need to use different welding wires according to different plates. Aluminum usually uses 5356 series welding wire (recommended) or 4043 series. Because aluminum welding wire is relatively soft, it is usually recommended to use 1.2/1.6mm diameter welding wire.

5.Wire Feeding Wheel and Wire Feeding Hose Selection:

• For copper wire, refer to stainless steel, using a V-shaped wire feeding wheel and carbon steel wire feeding hose.
• For aluminum wire, use a U-shaped wire feeding wheel and a shorter graphite wire feeding hose (about 3 meters).

6.Parameter Selection:

• Because aluminum and copper materials have high reflectivity and high thermal conductivity, a high energy density is required. Therefore, the recommended equipment type and welding parameters are higher than those for stainless steel of the same thickness.

7.Welding Process and Angle:

• When laser welding of highly active materials such as aluminum alloys, keep the gun head at a 45-degree angle to the workpiece. Apply slight pressure to the gun head to ensure that the welding wire is flush with the plate. When emitting light, relax your hand and feel the thrust of the wire feeding (the thicker the welding wire, the greater the thrust). Follow the thrust to guide the route of the gun head. Avoid using too much force so that you cannot feel the thrust and keep pushing the gun head back.

8.Selection of Protective Lens:

• Some customers purchase inferior protective lenses themselves. To reduce costs, ordinary substrates are selected, the coating process is not guaranteed, and the transmittance is low, which cannot withstand laser penetration, resulting in lens blowing and a short life. It is recommended to purchase laser accessories from regular channels of manufacturers to ensure quality and service life.

9.Laser Core Diameter Selection:

• As we all know, when the laser power is constant, the smaller the core diameter, the greater the power density, so the brightness of the laser is very important. The higher the brightness, the stronger the equipment’s anti-high reflection ability and the higher the density threshold of the breakthrough material. The easier the material is to absorb, the easier it is to process high-reflection materials.

By following these considerations, you can significantly improve the quality and efficiency of laser welding of highly active materials like aluminum and copper.