In the past few decades, the laser marking industry has made remarkable progress. Now, there are a large number of laser marking system suppliers in various industries around the world. The most important change in this market is the introduction of low-power pulsed fiber lasers, which have now evolved to provide almost all suppliers with such fiber laser marking equipment within their product offerings.
The wavelengths of these lasers typically fall into the near-infrared (NIR) range of around 1070 nm, making them ideal for marking most metal products because they have lower reflectance than longer wavelength CO2 lasers.
But even in this wavelength range, the difficulty of marking different metals is not the same. Aluminum, copper and their alloys are widely used in almost every industry. These materials can be laser-marked, but it is sometimes difficult to print dark marks that are clearly visible to the naked eye on such metals under low heat conditions. In addition, a proven technique has shown that highly transmissive materials typically perform marking and surface texturing processes with minimal damage within a pulse width that is not associated with unexpected nonlinearities.
Laser surface treatment
In the broad field of industrial laser material processing, the term laser surface processing is often used to describe a range of processing activities using continuous wave (CW), near-infrared laser sources with several kilowatts of power. However, the above process is quite different from the techniques described herein that can be considered as micron and nanoscale surface applications. Many processes using short pulse picosecond (10-12) and femtosecond (10-15) ultrafast lasers have been identified and there are many related publications.
The main disadvantage of these processes is that even in the low-power series of these laser categories, their investment and operating costs remain high. Since the processing speed is usually dependent on the average power of the laser, the laser processing cost under actual surface coverage conditions may be too high for most industrial laser users.
Recently, the pulse width range of mature nanosecond pulsed fiber lasers has been extended to sub-nanoseconds, with the attendant increase in peak power capability on the order of magnitude. This has made it possible to develop a new laser surface machining process using a cost-effective long picosecond laser source.
Although these techniques are often referred to as laser surface treatments, these processes are mechanically related to laser marking because they are limited to the surface treatment of the components and typically require a combination of laser ablation and melting processes. Figure 1 attempts to classify this wide range of processes using industry-accepted terminology and the main physical mechanisms involved.
The well-known advantages of fiber lasers ensure that they become the dominant choice for most applications shown in Figure 1. Here we mainly introduce the purpose of improving the understanding of micron-scale laser applications for materials that are generally considered to be difficult to mark with standard infrared wavelengths, such as copper and glass. Standard application.