Fiber Laser vs CO2 Laser Cutting Aluminum

Aluminum alloys reflect laser energy very strongly, so they must be cut on machines equipped with anti-reflection protection. Understanding both the reflection generated at the workpiece surface and the resulting heat flow inside the material helps improve processing performance and cut quality.

Observed Performance

Cutting Speed

The relationship between sheet thickness and cutting speed was compared when 2.5 kW fiber and CO₂ lasers cut A5052 aluminum alloy with nitrogen assist gas. The thinner the sheet, the larger the speed difference. For 1 mm sheet, the source data gives a CO₂-laser speed of 4.5 m/min and a fiber-laser speed of 27 mm/min. [TO VERIFY: the source reports the fiber-laser unit as mm/min.] As thickness increases, the speed difference decreases sharply.

The principal processing conditions were as follows:

CO₂ Laser

• Power: 2.5 kW
• Processing-lens focal length: 5 in
• Assist gas: nitrogen
• Assist-gas pressure: 0.8–1.2 MPa

Fiber Laser

• Power: 2.5 kW
• Processing-lens focal length: 4 in
• Assist gas: nitrogen
• Assist-gas pressure: 0.6–1.2 MPa

Cut-Surface Quality

As with stainless-steel cutting, the fiber laser produces a rougher cut surface than the CO₂ laser. The difference increases as workpiece thickness increases.

There is no evident difference between fiber- and CO₂-laser cutting in the condition of burrs on the underside. As thickness increases, burr formation is more readily affected by assist-gas pressure and by the kerf width produced through focal-position adjustment.

Why the Difference Occurs

Because thin-sheet cutting produces relatively few burrs, the settings can prioritize melting capacity. The focused spot is placed at the workpiece surface (Z = 0), where laser energy density is highest. A fiber laser is therefore advantageous because its beam can be focused into a smaller spot.

For thick plate, however, burr prevention requires adjustment of the focal position, widening of the kerf, and sufficient assist-gas pressure to expel molten metal. These measures reduce energy density in the processing zone, so the cutting-speed difference between fiber and CO₂ lasers becomes smaller.