Why CO2 Laser Not Ideal For Engraving Metal

Wavelength: CO₂ lasers wavelength is 10.6 micrometers, metals are highly reflective at this wavelength, it is difficult for the CO2 laser to effectively heat and engrave the metal surface.

Absorption: For effective engraving or cutting, the material needs to absorb the laser energy to heat up and either melt or vaporize. Metals do not absorb 10.6 µm wavelength efficiently, CO₂ lasers are less effective for this purpose.

Power Requirements: Even if a CO₂ laser has enough power to slove the reflective issue, it would require significantly higher power levels compared to other types of lasers that are better suited for metal engraving. 

Alternative Lasers: Fiber lasers and Nd:YAG lasers, are much more effective for engraving metals. these are also more compact and require less maintenance compared to CO₂ lasers.

Surface Quality: CO₂ lasers can cause thermal damage or produce rough edges on metals due to the inefficient energy transfer.