What is the core principle of laser welding?

Jun 28, 2025 Leave a message

Precautions for Laser Welding Machine When Processing Aluminum Metal

The core principle of laser welding is a technology that uses a high-energy-density laser beam focused on the material surface, causing the material to rapidly melt and form a molten pool, which solidifies upon cooling to achieve atomic-level bonding. The key mechanisms are as follows:

1. Energy Conversion and Material Melting

After being focused by an optical system, the laser beam (e.g., fiber laser, YAG laser) achieves a power density of 104∼107W/cm2. When the laser irradiates the material, photon energy is absorbed by the surface and converted into thermal energy, rapidly raising the local temperature above the material's melting point (or even boiling point) to form a liquid molten pool.

2. Core Differences Between Two Welding Modes

Based on power density and thermal interaction, laser welding is categorized into two typical modes:

Conduction Welding (power density 104∼106W/cm2):
Laser energy diffuses into the material through thermal conduction, resulting in shallow penetration and a large width-to-depth ratio of the weld (suitable for thin plates).

Deep Penetration Welding (power density ≥3.5×106W/cm2):
High energy instantaneously vaporizes the material, creating a "keyhole" effect-vapor pressure repels liquid metal, allowing the laser beam to penetrate deeply into the material. This significantly increases penetration (suitable for thick plates), with a small width-to-depth ratio (up to 1:10 or more).

3. Key Influencing Factors

Power Density: Determines the welding mode (conduction or deep penetration) and penetration depth, serving as the core parameter.

Material Properties: Such as reflectivity (aluminum reflects ~80% of 1070nm laser light, requiring higher power compensation) and thermal conductivity (aluminum's high conductivity necessitates concentrated energy).

Cooling Rate: Rapid solidification of the molten pool forms a dense weld, but high cooling rates may cause cracks in brittle materials.

Conclusion

The essence of laser welding is a "local melting-solidification process induced by a high-energy-density laser beam." By controlling parameters like power density and focusing mode, it enables efficient welding from thin sheets to thick plates, and from precision components to large structures.

--------------

Ryder

Send Inquiry