High reflectivity: Aluminum reflects over 90% of fiber lasers around 1060nm at room temperature. This means that most of the laser energy is reflected, preventing effective heating of the material.

Reflected light hazard: Reflected laser energy can return to the laser's interior, causing permanent damage to core components such as the optical fiber and laser module. This presents the greatest risk.

Material Properties:

Low melting point, high thermal conductivity: Aluminum has a low melting point (approximately 660°C) but conducts heat very quickly. This results in rapid heat dissipation, making it difficult to form a stable molten pool at the cutting point, leading to discontinuous cuts or rough cross-sections.

Viscous melt: Molten aluminum is highly viscous and difficult to be blown away by the assist gas, resulting in severe dross at the bottom.

Oxide layer: The aluminum oxide (Al₂O₃) on the surface has an extremely high melting point (approximately 2050°C). This "hard shell" hinders the initial piercing and stable cutting process.