The laser is one of the most popular marking technologies in industrial production. Metals, plastics, ceramics, and other materials can be marked with laser radiation at wavelengths of 1064 nm (infrared), 532 nm (green), and 355 nm (ultraviolet). As a tool, lasers can be applied to digital, text, trademark or machine-readable codes, such as data matrix codes with high information density and arranged in tight spaces at different scales.
Fiber laser marking machine
In this way, high-speed marking can shorten the cycle time of the production process, while at the same time not requiring expensive up-front work and final finishing work. In addition, lasers can be easily integrated into automated production lines. With the user-friendly program interface, you can quickly switch to a new process; the result is a product with good repeatability and resistance to ageing and wear.
In plastic marking applications, the potential of lasers is far from being realized. In addition to the benefits mentioned above, the increasing popularity of frequency-doubled lasers and triple-frequency lasers, as well as the diversity of materials and processes, is opening up new areas for laser applications in the plastics industry.
For plastic marking, Q-switched short-pulse solid-state lasers orfiber lasers are a common type. These lasers typically have an average power of less than 100 W with a pulse duration between 10 and 100 ns. The pulse frequency is up to 120 kHz, and in the case of fiber lasers, it is even up to 1 MHz. In this way, the interaction with the material to be identified can be fine-tuned. Short pulse times result in high pulse peak powers of tens of kilowatts reaching an average of 10W.
The laser is a diode-pumped laser with high energy efficiency. They have excellent focusing power and are therefore ideal for fine marking. Diode-pumped solid-state lasers have high beam quality, resulting in a small focus diameter for the laser beam during marking. In this way, a precision marking track width as small as 30 m can be realized on minute parts.
Adaptation of absorption characteristics.
Lasers used for marking typically produce radiation in the infrared wavelength range. Green lasers andUV lasers target plastic and semiconductor materials. In special marking applications, the use of UV wavelengths opens up new possibilities for laser marking on plastics. The short wavelength directly produces a photochemical reaction with the plastic composite without heating, so that it does not damage the material; especially some of the more critical materials, plastics containing flame retardants, or sensitive electronic components. These lasers perform high-contrast marking at very high speeds without any negative impact on surface quality.
The most important point is that the plastic must absorb laser radiation to a large extent. The biomacromolecule structure of plastics typically only absorbs light in the ultraviolet range and far-infrared (IR) range (wavelength 10.6 m). Additives, fillers, and pigments in engineering plastics have a large effect on the absorption characteristics of the material so that the plastic can better absorb the laser beam in the near-infrared range or in the visible green laser range. With this method, higher marking speed and better contrast can be obtained.
Therefore, they cannot meet the high requirements for laser marking. In order to achieve durable, high-definition, high-quality marking of these materials in short processing time, special laser-sensitive additives are required. They greatly improve the marking ability of materials.