Choose the right laser marking scheme

As a fast and clean product marking technology, laser marking is rapidly replacing the traditional old product marking technology, especially inkjet technology. As the market continues to increase the tracking and traceability requirements of product parts, especially in applications such as medical equipment, automobiles and aerospace, these requirements are driving the exponential growth of applications for direct marking of parts information.

　　 In view of the extensive market demand for direct marking, laser marking technology is increasingly gaining popularity in the market. The information directly marked on the part is usually letters, numbers, bar codes or Data-MatrixTM codes that are easy to read. Laser marking technology is popular in the market due to its simple and flexible automatic marking method, environmental friendliness and low cost of ownership. At present, there are a variety of laser marking schemes on the market. Each marking scheme has its own marking characteristics and the range of materials suitable for marking. When selecting, users need to choose the most suitable laser marking according to specific application requirements. Standard scheme.

　　Introduction to laser marking

　　Laser marking uses the focused beam output from the laser to interact with the target object to be marked, thereby forming a high-quality permanent mark on the target object. Figure 1 shows the schematic diagram of a typical laser marking machine. The beam output from the laser is controlled by two mirrors mounted on a high-speed precision motor to realize the motion marking of the beam. Each mirror moves along a single axis. The movement speed of the motor is very fast, and the inertia is very small, so that it can realize the rapid marking of the target object. The light beam guided by the mirror is focused by the F-θ lens, and the focal point is on the marked plane. When the focused beam interacts with the marked object, the object is "marked". Except for the marked position, the other surfaces of the object remain unchanged.

　　 Generally, the laser marking system is mainly composed of a highly flexible and controllable laser source coupled with a high-speed and precise motion system through software and hardware. In addition to being able to achieve marking processing, laser marking systems usually also have mechanical processing capabilities such as cutting, drilling, polishing, scribing, and scraping.

　　In the laser marking system, software is used to control the laser beam to realize the marking of text, graphics, trademarks, bar codes, and Data-Matrix codes. The automatic marking function realized by software control enables the laser marking system to realize serialized marking of parts, date coding, variable text input, remote programming, input/output control and many other programming features.

　　Laser can quickly achieve precise and clean marking on metals and plastics, which makes laser marking suitable for most manufacturing processes. Laser can also be used for surface engraving (a process similar to marking). It can engrave marks that can be seen by the human eye and touched by the hand on the part representation. This is a processing method that changes the surface of the part. .

　　Laser marking is a non-contact processing process. The entire processing process does not require any consumables, is very clean, and is quite energy-efficient. In addition, compared with traditional marking methods, laser marking is also a very environmentally friendly processing process, which does not require the use of any ink or other chemicals. The laser marking process enables a highly flexible marking process to meet changing marking requirements. Laser marking is suitable for marking a wide range of materials. These materials include steel, aluminum, polyolefin, engineering and medical plastics, silicon, and many other materials.

　　Laser marking is very suitable for marking barcodes and 2D barcodes on the surface of materials. The quality and resolution of the marked code can be adjusted according to the space size of the marked surface and user requirements. In short, the laser marking system can achieve excellent marking data density while reducing the space required for marking codes.

　　Choose the right laser marking scheme

　　 The lasers used in laser marking schemes currently on the market mainly include: Ytterbium-doped fiber lasers, Nd:YVO4 lasers, green (532nm) lasers, ultraviolet (UV) lasers and CO2 lasers. In addition, there are still some high-power applications still using Nd: YAG lasers. Of course, with the development of technology, Nd: YAG lasers have gradually been replaced by the other types of lasers mentioned above.

　　 Each of the above-mentioned lasers provides different output wavelengths, and has different optical properties such as peak power and pulse width. Green lasers and ultraviolet lasers usually multiply the output of YVO4 laser with crystal elements, and convert the wavelength of the output light from 1064nm to 532nm and 355nm, respectively. According to the material to be marked, and the user's requirements for the clarity of the mark, the size of the character, and the amount of heat input to the part, different laser wavelengths are suitable for different applications. Figure 2 shows the different laser wavelengths suitable for marking applications. The following will introduce the marking features provided by different lasers and their applicable fields.

　　Ytterbium optical fiber marking machine: good marking quality and high cost-effectiveness

　　Ytterbium fiber laser uses laser light output from ytterbium-doped fiber, and its pump source adopts telecom-grade single-tube diode. This diode has a service life of up to 100,000 hours. In addition to the advantages of long service life, fiber lasers also have higher energy efficiency and less maintenance requirements, so they have the lowest cost of ownership.

　　Ytterbium-doped fiber laser marking machine has become one of the most commonly used laser marking technologies on the market. The fiber laser marking machine can achieve high-quality, contrast-marking marking on metal and plastic materials, and it can also be used for metal engraving and processing a wide range of other materials. Figure 3 shows an example of a product marked with a fiber laser marking machine. The material marked in the picture is glass-filled plastic.

Nd: YVO4 marking machine: specially designed for fine marking

　　Nd: YVO4 laser marking machine is specially designed for high-resolution fine marking applications. These applications often need to mark precise details or very small feature sizes. With excellent beam quality and a focus size of less than 0.001 inches (25μm), the Nd: YVO4 laser marking machine can achieve fine marking on metal, plastic and ceramic materials. In addition, since the Nd:YVO4 laser can achieve very high laser peak power (greater than 30kW) and very short pulse width (less than 20ns), this also provides the level of control needed to achieve high-resolution marking.

　　 Green laser marking machine: suitable for certain plastics, silicon and reflective metals

The visible green laser works at a wavelength of 532nm. It can achieve clear contrast marking on plastic materials, soft marking on silicon materials, and high-quality marking on reflective materials such as gold and silver. .

　　Ultraviolet laser marking machine: Realize extremely high-resolution marking of plastics and corrosion-resistant materials

The output wavelength of the UV laser marking machine is 355nm, which can provide unique marking characteristics. It can achieve excellent contrast marking effects on many other plastics that cannot be marked by lasers. For example, it can be used to mark medical catheters and highly resistant to corrosion. The 17-X stainless steel material. Compared with fiber lasers, Nd:YVO4 lasers and even green lasers, UV lasers can achieve the best marking quality on almost all materials. The 355nm wavelength further increases the range of plastic materials that can be marked. In addition, when marking metal materials with it, the heat input can be strictly controlled.

　　CO2 laser marking machine: the best choice for marking printed circuit boards, paper and wood

　　 The working substance of CO2 laser is composed of gas enclosed in a decompression aluminum tube. The pump energy of the CO2 laser is provided by radio frequency (RF) energy. The CO2 laser marking machine can mark plastics, but the markings are engraved and there is no surface contrast. The working wavelength of the CO2 laser marking machine is 10604nm, which can be widely used to mark organic materials such as paper and wood, as well as printed circuit boards (PCB) and glass. The CO2 laser marking machine is not suitable for marking bare aluminum, copper or brass and steel. Figure 4 shows the marking effect achieved by the CO2 laser marking machine on the PCB circuit board.

　　Nd: YAG laser marking machine: old laser engraving technology

　　Nd: YAG laser marking machine is mainly used for large-area metal marking (surface effect) and deep engraving applications (depth effect). These applications usually require higher laser power. At present, although the Nd: YAG laser marking machine has been largely replaced by other laser marking machines, it is still widely used in high-power (50~100W) applications. With the gradual elimination of Nd: YAG laser marking technology and the substantial reduction in the total cost of ownership of fiber laser marking systems, fiber laser marking technology, as a new force that continues to develop, is beginning to gain more in high-power market applications. Multi-market share.

　　Almost all applications that require direct marking or engraving, there are a variety of marking options. Laser marking technology provides a new solution for the direct marking process. The advantages of laser marking include: permanent marking quality; text, graphics, logos and data codes that can be marked; highly flexible marking methods; and a wide range of materials that can be marked. In addition, laser marking is a high-speed processing process that can be easily integrated into the user's production line. Moreover, laser marking is also a non-contact processing process, which further enhances its safety, and the entire processing process does not require any chemicals, so it is also very environmentally friendly.