Utoh,
Cermark, Thermark etc make an polar covalent bond between the coating and base material and while very strong it can depend on the base metals (a lot of hosts are some pretty dirty alloys that don't like chemical bonding). I do a LOT of engraving and won't touch the Cer/Thermark stuff where possible.
Plain gas CO2 lasers can be destroyed by trying to engrave aluminium, the index of reflectivity for Al is close to 90% and few lower quality lens's have an anti reflective coating both sides. Backscatter running back through the optical train can easily destroy tubes and lens's (usually the output coupler on the tube and final lens) so I would seriously recommend not trying it on anything less than a big industrial CO2 (even then it requires specialist set ups to process properly)
Yag is a different matter, they direct engrave on Al very well (and at quite low power) they can achieve a surface (sub 0.05/0.1mm depth) on Al quite easily and can run to 3mm depth for colour filling if really required using higher powers.
Fiber will also work on Al but the beam quality can be a little "off" on the cheaper Fibers if you want clear , very small engraved areas.
Compared to Yag/Fiber, cermark/thermark is expensive, the solutions or tapes cost quite a bit and the process is long winded for what you get.
To give some idea, a picture/text of 10 mm by 25mm on my Yag Galvo would usually get change out of 10 cents an item if I was doing a few and likely change from 2 bucks as a one off.
Engraving on anodised aluminium is totally different, a normal pretty low power CO2 gas laser will work from 25 watts upwards. All it does is leeches the colour from the hydroxide surface leaving a pale white on background look.
best wishes
Dave
maybe brass or titanium
