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Aluminium cutting is a burr problem more than a reflectivity problem

Modern sources handle the reflection. What still frustrates shops is a tenacious burr on the underside that adds a deburring operation nobody quoted.

By LasersNews Desk··2 min read
Workers weld metal structures in a bustling industrial factory, showcasing a dynamic work environment.
Photo by Hoang NC on Pexels

Aluminium's reputation as a difficult laser material comes from an earlier generation of equipment, when back reflection genuinely threatened the source. Modern fiber lasers with proper isolation handle it routinely. The problem that remains is what the cut edge looks like underneath.

Why aluminium burrs

Aluminium's thermal conductivity is roughly three times that of steel, so heat spreads away from the cut front quickly. Its oxide melts at a far higher temperature than the metal beneath, which changes how melt behaves at the kerf exit. And molten aluminium is more viscous in the relevant range than molten steel.

The combination produces melt that does not detach cleanly at the bottom of the cut. It adheres, solidifies and forms a burr that is tenacious enough to require mechanical removal.

What reduces it

Higher gas pressure. More momentum to expel melt, at the cost of consumption.

Nitrogen rather than air. Air cutting aluminium generally produces a worse edge, since oxidation makes the melt behaviour less favourable.

Focus position. Positioning focus lower in the material than a steel setting improves melt ejection at the exit.

Speed matching. Both too fast and too slow produce burrs, for different reasons, and the acceptable window is narrower than in steel.

Beam shaping. A wider kerf gives melt more room to leave, which is why a larger ring fraction often improves aluminium edges.

What shops actually do

Even well optimised, aluminium frequently leaves some burr on thicker material, and the practical response is to plan for deburring rather than chase a burr-free cut that the process may not support at the required rate.

The error that costs money is quoting aluminium parts as though they will come off the machine finished. Shops that discovered this late have generally repriced their aluminium work rather than found a parameter that eliminated the operation.

The alloy dimension

Alloy matters more than many expect. The 5000 series cuts differently from 6000 series, and highly alloyed material behaves differently again. A parameter set validated on one alloy is a starting point, not a solution, for another — and the material certificate is worth reading before blaming the machine.

This article was produced by the LasersNews AI desk and reviewed by our editors.

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