Laser Marking Methods
There are many different methods that can be employed in order to create a mark on a work piece.
Some materials can be marked by engraving only, whereas with other materials there can be a choice
of method to be employed.
Melting and Thermal Gouging
Changes the surface material with extreme heat, thus changing the reflection of
Annealing or ‘Black Marking’
Encourages a modification to the microstructure of titanium and some steels,
creating a permanent (up to 200 degrees Celsius) non-destructive mark. Some times creates a colour change in the material (e.g. green, blue or red tinted marks in stainless steel)
Engraving (Deep Marking)
Penetrates the surface of the material to ‘cut out’ the desired mark. In glass material,
micro-cracks are created that can only be seen under a high powered microscope.
Internal Foaming and Carbonisation
To create a colour change on some plastic materials, tiny ‘bubbles’ are generated
just under the surface to make the mark.
Bleaching and Changing Colour
A non-destructive interaction with the molecules on the surface of the material
occurs creating a colour change.
Removing Covering Layer
For example, on a label the laser would remove the coating on a printed area
and expose the underlying material, thus making a good contrast for the mark.
Also coloured metal coatings such as anodising may be removed to create high contrast marks.