Laser marking is a technique for using a beam to mark different sorts of items. The theory of laser marking is that the reflective perception of a material it strikes is somehow changed by a laser light. This can happen through a variety of methods:
- Material ablation (laser engraving); often scraping such coloured surface layers
- Melting a metal, thereby modifying the structure of the substrate
- Slight combustion (carbonization) of pulp, canvas, timber or composites etc.
- Conversion (e.g. bleaching) of polymers in a composite shell (laser technology additives)
- Advancement of material if, for example, any additive evaporates
It is possible to quickly write notes, icons, serial numbers and other illustrations using a vector scanner or a contour scanner by manipulating the laser light (e.g. with two movable reflectors). Another approach is to use a filter on the workpiece material that is visualized (projection marking, mask marking). This approach is simpler and quicker (even with relevant rotating workpieces) but less versatile than screening.
Laser labelling has an immense number of applications:
- The inclusion of part numbers, “use by” dates etc. on packets of food, containers, etc.
- The addition of checkable data for quality control
- Printed circuit board (PCB) marking, computer parts and wires
- Print labels, bar codes and other spec sheets
Laser marking has a range of advantages relative to other marking methods, such as inkjet printing and electromagnetic markings, such as very high processing frequencies, low operating costs (no supplies used), continuous high quality and durability of the results, avoidance of degradation, the ability to construct very small features, and very improved processing versatility. With significantly lower CO2 lasers, plastics, metal, canvas, cardboard, cloth and canvas are also labelled. Short laser wavelengths are important for marking materials like gold that have too little absorption in the 1-μm visible range.
Necessitates for laser taggings:
A variety of requirements must be met by lasers for labelling implementations. Typical ones are given below:
- On the workpiece, some certain visual maximum absorbance or fluency must be attained. (Marking processes often exhibit a certain level, under which no acceptable outcome can be obtained, even with several bursts. This includes an acceptable mixture of maximum output or trigger power and light diameter at the target, and there is also some effect on the pulse duration. For the sake of greater fidelity, close targeting is often required, and this implies that high beam efficiency is necessary along with a favourable work distance.
- The laser requires to provide a high-quality resonant frequency rate for fast processing, which implies a certain average output along with the applied voltage. The resonance frequency of a Q-switched laser in some systems is restricted by the potential power rating, the laser parameters or the possible pulse length in other systems.)
- The Q-switched pulse stream should, for some time periods, be turned off in certain situations. The problem also occurs that the very first pulse has a greater energy, which can ruin the efficiency of the labelling.
- The laser configuration should be simple and complex ventilation procedures should not be necessary. It is beneficial and always possible to wind drying.
- Costs of ownership must be reasonable, not only in terms of infrastructure costs, but also in terms of service duration and repair.
As industrial environments can be tough, for proper functioning, a reliable laser design is important.
Various sorts of lasers may be most appropriate for a labeling procedure, depending on the particular situations.