Laser marking is an extremely common type of industrial laser application. The systems employed use various lasers and optical systems to mark an endless category of metals, plastics, and ceramics. The technology uses an alphanumeric code that is imprinted on a surface; the engraving can mark the manufacturing date of a product, or it can feature a serial number. Laser marking prides with a lot more benefits than conventional techniques because it works alone and it is incredibly precise.
Common benefits of laser marking
- Top-quality markings
- Permanent markings
- Low operation costs and increased efficiency
- Excellent accessibility even on surfaces that are not regular or flat
- No special environment required to perform the markings
- Non-contact marking
- Easy to integrate and automate (computer controlled movement is used to direct the writing pattern)
- Precise positioning of the laser beam
- High speed and high reproducibility
A closer look at the laser making mechanism
Marking process abide by a series of processes: bleaching or color changing of the material, black carbonization, physical alteration of a surface, highly-controlled alteration of a surface through melting, vaporization through scribing a groove into a material. Simply put, everything comes down to annealing, vaporizing and melting of the material about to be marked. Each method has a very specific effect and the end result differs.
Vaporization for example, is a marking technique that engraves the material with a precise depth. Melting uses thermal-chemical reactions to create contrasting marks (the most common material used in this case is plastic), and annealing is a method that produces a mark (usually dark-colored) without penetrating the surface of the material in any way.
Laser marking methods
Laser marking technologies adhere to two principal marking methods: mask marking & beam-deflected marking. Both of them make use of optical techniques to boost power density and etch the surfaces about to be marked. When mask marking, the mark is protected by a stencil on the work piece. The technique uses pulsed lasers to craft the desired engraving.
The beam-deflected method uses two galvanometer mirrors to direct the laser beam; as well as a lens system that is aimed at the object about to get marked. Then a special software program is used to control the mirrors. The marking is performed by the beam in two directions: x and y. This method is extremely flexible, and it has the potential to transmit an increased volume of information. The beam-deflected method used continuous wave lasers.
When comparing these two marking techniques, we can conclude that mask marking features increased marking speeds; this is because the duration of the laser pulse is situated between micro and nano seconds. This means that the work piece about to get marked doesn’t have to stop. The beam-deflected marking method also packs great benefits. For starters, it has a more sizeable marking area; mask marking areas a very small due to the limited spot size of the beam and energy per pulse inflicted.
When it comes to which of the two are more flexible, we must mention that in mask marking the required patterns are manufactured by the masks. It can be time-consuming to craft a single mask, which is why this method is a lot more recommended in high volume productions without changing the patterns. Beam-deflected markings feature patterns produced by software systems. This means that changing the patterns is done with a lot more ease. In terms of cost, beam-deflected laser marking is more expensive because the scanning systems involved are more high-priced.
Laser marking applications
Lasers are being employed in a wealth of applications in many different industries. In photographic invisible and imaging coding for example, the lasers create high resolution images meant to stimulate photos that are black and white. High speed marking technologies are pretty common in the packaging industry because they make information tracking a lot easier; furthermore, it is simpler for manufacturers to mark expiration dates on their products.
Because they’re extremely fast, flexible and accurate, lasers are a convenient alternative to conventional marking technologies. Fortunately, increasingly more companies are starting to understand their benefits, and soon enough even more businesses will turn to laser marking procedures to keep their product line more organized.
By Michael Clark and Fimark.co.uk