Plastics and Polymers Marking
Plastics and polymers are the most variable materials that are marked with
lasers. There are so many different chemical compositions that you cannot
categorize them easily. Some generalizations can be made in terms of markings
and how they will appear, but there is always an exception. We recommend test
marking to ensure the best results. A good example of material variability is
delrin (AKA Acetal). Black delrin is easy to mark, providing stark white
contrast against the black plastic. Black delrin is truly an ideal plastic for
showcasing the capabilities of a laser marking system. However, natual delrin
is white and does not mark at all with any laser. Even the most powerful laser
marking system will not make a mark on this material.
Fiber laser is capable of marking on plastics and
polymers, the ideal system for your application depends on your marking
requirements. Because plastics and some polymers are soft and can burn when
marking, Nd: YVO4 or Nd:YAG may be your best bet. These lasers have lightning
fast pulse durations resulting in less heat on the material. 532nm Green lasers
can be ideal as they have less thermal energy transfer and also are better
absorbed by a wider range of plastics.
The most common technique in plastic and polymer
marking is color changing. This type of mark uses the energy of the laser beam
to alter the molecular structure of the piece, resulting in a change in the
color of the substrate without damaging the surface. Some plastics and polymers
can be lightly etched or engraved, but consistency is always a concern.