Process Date: July 2000
 
Marked with FH "Index" marking head using 18 watts at 15"/ second.
Marking plaques and presentation pieces made from marble, granite and similar substances can be achieved in various ways. Surface marking, with very little penetration into the material, is fairly straightforward, generally requiring less than 25 watts of power. The resulting mark is usually clean and well-defined. Some synthetic materials are designed specifically for laser marking, and so require only a minimal amount of parameter optimization. Difficulty arises, however, when an increased engrave depth cannot be achieved in a single pass of the laser. In this case, a number of considerations must be taken into account:

    1. As the engraved depth increases, the engraving surface moves further away from the optimal focus position.

    2. Ejected material and fumes tend to stain the surrounding area.

    3. The angle of the beam may reduce resolution at the outer edges of the marking field. (does not apply to xy plotter type systems)

    4. Some materials become amorphous from repeated laser passes.

For optimal results, the depth of focus of the optic should match the depth of engraving, and close proximity, high suction devices should be implemented.