Three minutes to discuss several ways of cutting glass by using our picosecond lasers.
Glass is widely used in various aspects of daily life. Such as construction, 3C electronics, automotive, and solar cell devices. Cutting and shaping are crucial steps in transforming bulk glass into display screens, windshields, and other terminal products with various sizes and shapes.
Traditional glass cutting methods include wheel cutting and CNC grinding. The main disadvantages of traditional cutting processes are poor shaping accuracy, low material utilization, and the generation of debris.
Cutting non-regular shapes also results in reduced precision and lower efficiency. For high edge requirements, additional grinding processes are necessary. These make traditional machining methods more suitable for processing large-sized workpieces.
In addition, there are cutting processes such as melting and thermal stress cracking which use CO2 lasers as auxiliary tools. The glass is softened or melted by laser heating, or a groove is generated by high-pressure gas blowing, or rapid cooling causes it to fracture along a specified path. The cutting quality is better than that of traditional cutting methods but compared with ultrafast laser cutting processes represented by picosecond lasers, it is slightly inferior overall.
The principle of using a picosecond laser to cut glass and other materials is that when the pulse width reaches the picosecond level, the shorter the pulse, the faster the energy is transferred to the electrons, and there is not enough time for the electrons to achieve thermal equilibrium with the lattice. For metals and most other materials, the typical electron-phonon relaxation time is between 1 and 10 ps or even shorter. When a picosecond laser pulse of around 10 ps emitted by the Picosecond Laser is applied to the glass surface, the instantaneous high energy density deposition changes the way electrons are absorbed and transported, and the heat from the electrons begins to diffuse into the surrounding lattice, causing a phase explosion, thus removing (cutting) the material on the glass surface from point to line. The entire process avoids linear absorption, energy transfer, and diffusion of the laser, so there is almost no thermal effect, and this type of picosecond laser processing method is also known as cold processing. Overall, the cutting edge has a better texture, with less chipping and fewer cracks, and higher processing efficiency.
Through ongoing exploration and the development of more advanced techniques, picosecond lasers have emerged as a highly effective cutting source for glass, offering practical and efficient methods such as whole cutting, line breaking segmentation, wire cutting, and Bessel beam cutting.
The whole cutting using a laser to directly create the desired shape, without the need of additional processing steps. This method is particularly suitable for cutting thin glass, and the high power, narrow pulse width, and high peak power of picosecond lasers can often achieve direct penetration and one-step molding, resulting in smooth cutting edges without the need for secondary processing. Whole cutting is an attractive process for glass cutting.
Line breaking segmentation, also known as scribing, is more like using the laser as a tool to create a groove on the glass surface through back-and-forth movement. This groove is then broken apart using mechanical force or a CO2 laser, similar to the cutting principle of a cutting wheel. However, line breaking segmentation results in less edge chipping and higher quality cutting surfaces.
Wire cutting takes advantage of the phenomenon of filamentation, which occurs when high-power picosecond lasers in a transparent medium do not diverge significantly, allowing the laser to travel much farther than the diffraction limit and creating a plasma channel, often referred to as a “light filament.” The process of filamentation involves two main physical mechanisms: self-focusing and self-defocusing. The laser beam achieves long-distance propagation in the dynamic balance between these two mechanisms and forms micro-level holes in the glass workpiece. By controlling the relative movement of the glass workpiece with respect to the laser beam to create equidistant micro-holes and optimizing the spacing between them to create radial microcracks, external forces can be applied to these cracks to make the glass break along the cracks, achieving the cutting purpose. Wire cutting produces relatively clean and tidy glass sections.
Bessel beam cutting is a high-quality cutting method for transparent materials, such as glass, achieved through the use of a Bessel cutting head. The Bessel cutting head is similar to a special parameter focusing lens (beam shaper), which, when integrated into a laser, forms a laser beam generated by long-distance interference. This beam allows energy to concentrate and propagate inside the transparent material without diffraction, and the depth of focus can be several millimeters. The temperature and energy distribution are more uniform, and the energy density is very high, allowing for deep ablation of glass materials and completion of the cutting process according to the set cutting path. Bessel cutting does not cause internal cracking in the glass, so the damage to the glass strength is minimal, ensuring a smooth and flat cutting surface with no chipping and high-quality cutting edges. Bessel beam cutting is capable of meeting the cutting requirements of various shapes and angles of full-screen glass panels.
As we can see, the picosecond laser cutting technology provides glass cutting with a confident choice, with fast speed, high precision, no tooling requirements, and easy integration into large-scale production lines, allowing for automation and good economic benefits. Currently, picosecond laser cutting is not only used for glass cutting, but also in the processing of hard and brittle materials such as sapphire, ultra-thin glass substrates, and ceramic substrates, effectively improving cutting quality and efficiency.
The TianGong series industrial picosecond laser produced by Fuzhou NAFEI optoelectronics features a compact structure, high stability, and a unique hybrid laser amplification system that enables higher power output with single wavelength. These characteristics make it an ideal product for various applications in the precision machining and material processing fields.
Based on the fiber-solid hybrid laser amplification structure, the product can be configured with different repetition rates and output wavelengths according to different application needs. The repetition rate can be adjusted from single pulse to 20 MHz, and the product also features a Burst mode. The available wavelengths range from infrared, green to ultraviolet. The product provides ultra-short picosecond pulses (pulse width < 10 ps) with excellent long-term stability and pulse stability, beam quality of M2 < 1.3, and power stability (RMS) < 1%
It can work in a 24*7 operating environment, saving packaging and operational procurement costs for customers.
Please visit our website https://chinanafei.com/ or contact Megan@minoptronics.com for more detailed information
