Laser induced separation technology
Recently, thanks to the progress of carbon dioxide laser performance, an economical and practical new laser processing technology for glass cutting has come out. Engineers and technicians have found a cutting method - using a low-power laser to separate the glass without melting and other thermal effects. This is the laser induced separation technology. Its basic principle is to "separate" the glass by using the stress caused by the laser.
It is found that using a carbon dioxide laser with an average output power of 150 watts, an elliptical focal point is formed on the glass surface by focusing the optical path through the lens, so as to ensure that the laser energy forms a uniform and optimal distribution on both sides of the cutting line. Due to the absorption characteristics of glass to laser, almost all light energy is absorbed by the 15 micron area on the glass surface. Moving the focus can form the required cutting line. As long as the appropriate moving speed is adopted, the ideal cutting effect can be achieved, which can cut fully without melting the edge of the slit.
Technical details needing attention
In order to cause the glass to break, a small initial crack needs to be drawn at the starting point of the cutting line by mechanical method before cutting.
A key component in laser cutting is the quenching gas nozzle. When the focus light point moves, the quenching gas blows the cold air to the heated area of the glass surface through the nozzle, and quickly quenches it. After such treatment, the glass will break along the direction of the maximum stress, that is, the cutting direction set in advance, and finally realize the separation of the glass according to the cutting path.
The selected laser power and scanning speed of the light spot are different, and the fracture depth caused by stress is also different, which ranges from 100 microns to a few millimeters. Therefore, with this method, glass with a thickness of 100 microns to a few millimeters can be cut at one time. In addition to the laser power and cutting speed, the fracture depth is also closely related to the expansion coefficient of the material itself. Generally speaking, for the glass cut by laser-induced separation method, the minimum expansion coefficient should reach 3.2x10-6k-1. This is not a very high threshold, because most ordinary glasses meet this requirement.
Main advantages of laser induced separation
Compared with the traditional mechanical cutting method, the laser induced separation method has several outstanding advantages. First, the cutting can be completed in one step, and the cutting process is dry without cutting fluid; Secondly, the edges of the cut glass are smooth and neat, without subsequent cleaning and polishing; Moreover, the laser-induced separation process produces high-strength, naturally tempered edges, which will not produce tiny cracks; Finally, the laser induced separation method is used to cut the glass, which avoids unexpected cracks and breakage, reduces the defective rate, and effectively improves the output and quality.