Glass is an important industrial material, which is used in many industries of the national economy, such as automobile industry, construction industry, medical treatment, display, electronic products, small optical filters as small as a few microns, the glass substrate of laptop flat panel display, and large-scale glass plates used in large-scale manufacturing fields such as automobile industry or construction industry.

The remarkable characteristic of glass is hard and brittle, which brings great difficulties to processing. Traditional glass cutting methods use cemented carbide or diamond tools, which are widely used in many applications. Its cutting process is divided into two steps. Firstly, the glass is made of diamond tip or cemented carbide grinding wheel, which produces a crack on the surface of the glass; Then, the second step is to use mechanical means to separate the glass along the crack line.

However, there are some defects in this method. The removal of materials will lead to the generation of debris, fragments and micro cracks, which will reduce the strength of the cutting edge and require another cleaning process. The deep cracks caused by this process are usually not perpendicular to the glass surface, because the division line generated by mechanical force is generally non vertical. Moreover, the output loss caused by mechanical force acting on thin glass is also a negative factor.

These defects can be improved by using stress-free glass and further optimizing the tooling for segmentation. However, it is still impossible to completely avoid the systematic contradiction between the vertical cutting line and the prevention of edge debris / cracks. The development of laser technology has brought solutions to these quality problems.

Laser scribing and segmentation

Different from traditional mechanical cutting tools, the energy of laser beam cuts the glass in a non-contact way. This energy heats the specified part of the workpiece to a predetermined temperature. The rapid heating process is followed by rapid cooling, resulting in a vertical stress band in the glass, and a crack without debris or cracks appears in this direction. Because cracks are only caused by heat, not mechanical reasons, there will be no debris and microcracks. Therefore, the intensity of laser cutting edge is stronger than simultaneous interpreting and segmentation. The need for finishing is also reduced or not needed at all. In addition, the occurrence of glass fragments can also be completely avoided.

For laser engraving, under the action of laser beam heating and subsequent cooling process, the glass surface is marked with a depth of about 10mm (about 10% of the glass thickness). The glass can then be split in the direction of the engraving. Because this technology does not produce any glass fragments, the common rough edges and low strength of cutting edges are avoided, and the subsequent polishing and grinding processes are no longer needed. More importantly, compared with the glass segmented by traditional methods, the glass processed by this method has a crushing resistance of up to three times. For glass with a thickness between 5mm and 1mm, it is possible to complete the overall cutting in one step. Subsequent steps such as grinding and polishing are no longer required. The strength of the cutting edge can be measured by the standardized four point bending test from din-en 843-1. A piece of glass is fixed on two rollers, and the other two rollers are used to generate the required bending force on the upper surface of the glass. Under this force, the glass can be divided into two parts. The test is repeated about 100 times to obtain appropriate reliable statistics on the possibility of segmentation.

In most cases, laser scribing and cutting are the choice of mass processing. Its advantages lie in high processing speed, high precision and simple parameter setting. However, when cutting many different lines and processing time is sufficient, overall cutting is a more attractive method because it has dry cooling and no additional cutting steps. In both cases, high-quality cutting edges will be produced. It can be seen that if laser cutting glass is used, it can not only save time, but also improve the processing quality.

Application of laser cutting glass technology

Transplanting a new and mature technology to a mass production line for processing high-tech products is not easy. From the customer’s point of view, before implementation, the technology must be an automated and reliable solution, which has not only been fully proved, but also considered the economy. In practice, the application of innovative technology is only effective in two cases: the introduction of new products requires new production means to realize innovative characteristics, or reduce production costs by reducing processing steps, or the existing production needs huge improvement of production mode to alleviate the economic pressure.

In the flat panel display industry, the promotion of laser cutting technology took five years to find its place in the production line, provided that it has experienced thousands of hours of application verification on many processing lines. It is usually used in the production of glass or other fragile components in the communication industry, such as fragile glass or other products that are considered to be used in the production of fragile glass or mobile products.

Machining is usually carried out in clean rooms, just as in the biochemical industry, because these are very sensitive to particles produced by traditional cutting or grinding steps. For example, base materials covered with DNA codes (biochemical barcodes) or materials cut into pieces by laser are used for product testing. For laser cutting technology, the next most potential application industry will be solar energy industry and automobile industry.

Just like the development of laser technology in the metal processing industry for many years, the laser cutting technology for glass processing will continue to develop; This technology will be widely used in the processing of different products to replace the traditional means. However, the traditional glass processing method will maintain its important position in the processing of most glass products in the future. Generally speaking, the processing quality of cutting edge is not very high in these applications.

Laser shape cutting is an innovative technology that will find a place in the electronics, automotive or construction industries. In addition to laser cutting glass, many other means of laser processing glass are in the further development and experimental stage, such as drilling, chamfering, coating removal and so on. These processes require different kinds of lasers, such as green laser.