Anodised aluminium is the easiest metal to mark: the laser removes the coloured anodised layer and reveals the bright aluminium beneath. A crisp, permanent mark, achievable even with a diode.
Settings: what really matters
You are not engraving metal but removing a layer a few microns thick. A 10 W diode manages it at moderate speed; a 1064 nm fibre source is far finer and faster, and can additionally blacken bare aluminium.
The mark is a light contrast on a coloured background: black anodising gives the best result, red and blue are good, natural (clear) anodising gives weak contrast because there is almost nothing to remove.
Do not chase maximum power: past the threshold that removes the anodising you start melting the aluminium and the line turns dirty grey and uneven.
Risks and finishing
Metal reflects the beam. Never mark a mirror-polished part without proper protection, and keep the lid closed: a single reflection is enough to damage an eye or the machine's optics.
Little smoke, but fine metal particles: extraction is still needed, and the lens needs cleaning more often than you would think.
A microfibre cloth is all that is needed afterwards. Avoid alkaline cleaners or acetone, which can attack the coloured anodising around the mark.
Every figure on LaserSettings comes with the machine, the laser source, the material and the thickness it was tested on. A setting published for a 10 W diode says nothing about a 40 W CO2, and a setting for 3 mm says nothing about 6 mm: check those four things before you copy any number.
Settings are confirmed or disputed by the members who reproduce them, so reliability comes from cross-checking rather than popularity. Photos of the result — cut edges, engraving shades, scorching — tell you more than a single number found on a forum.
Whatever the material, treat a published setting as a starting point: run a small power/speed test grid on an offcut, clean the lens, redo the focus, work with fume extraction and air assist, wear glasses rated for your wavelength and never leave the machine unattended.