Views: 0 Author: HanTenCNC Publish Time: 2021-08-20 Origin: Site
In industrial production, laser is one of the most popular marking technologies. Metals, plastics, ceramics and other materials can be marked with laser radiation with wavelengths of 1064 nm (infrared), 532 nm (green light) and 355 nm (ultraviolet light). As a tool, laser can be applied to numbers, texts, trademarks or machine-readable codes, such as data matrix codes with high information density and arranged in tight spaces at different scales.
In this way, high-speed marking can shorten the cycle time of the production process, and at the same time, does not require expensive preliminary work and final finishing work. In addition, lasers can be easily integrated into automated production lines. Through the user-friendly program interface, it can quickly switch to a new process; the result is a product with good repeatability, aging and abrasion resistance.
For plastic marking, Q-switched short-pulse solid-state lasers or fiber laser source are commonly used types. These laser source usually have an average power of less than 100W, and the pulse duration is between 10 and 100ns. The pulse frequency can reach 120kHz, and in the case of fiber laser source, it can even reach 1MHz. In this way, the interaction with the material to be marked can be fine-tuned. The short pulse time results in a high pulse peak power of tens of kilowatts reaching an average value of 10W.
The laser is a diode pumped laser with high energy efficiency. They have good focusing ability and very suitable for fine marking.
The diode-pumped solid-state laser has a very high beam quality, which enables the laser beam in the marking process to obtain a small focus diameter. In this way, precision marking track widths as small as 30 m can be realized on tiny parts.
Laser source used for marking usually produce radiation in the infrared wavelength range. Green lasers and ultraviolet lasers are aimed at plastics 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 reacts with the plastic compound without heating, thereby not causing damage to the material (Figure 1); especially for some more picky materials, such as 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 biological macromolecular structure of plastics usually 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 great impact on the absorption characteristics of the material. In this way, the plastic can better absorb the laser beam in the near-infrared range or the visible green laser range. Through this method, higher marking speed and better contrast can be obtained.
Some plastics, such as polyethylene (PE), polyoxymethylene (POM), or polyurethane (PU), show only weak contrast (Figure 3). Therefore, they cannot meet the high requirements of laser marking. In order to obtain durable, high-definition, and high-quality marking results for these materials in a short processing time, special laser-sensitive additives are required. They greatly improve the marking ability of the material.
Although lasers can be widely used in marking, a comprehensive solution is still very unique. The best marking process can only be verified through close cooperation between the customer and the laser supplier. Parameters such as wavelength, quality (contrast, homogeneity, resolution and clarity), marking speed, and customer requirements, etc., play a decisive role in finding the most correct laser and the best settings.