Laser cutting technology for glass

Glass is an important material, which is used in many industries of national economy, such as automobile industry, construction industry, medical treatment, monitors and electronic products, etc., large-size glass panels used in large-scale manufacturing files such as automobile industry or construction industry, small optical filters as small as a few microns, glass substrates for laptop flat panel monitors.

There are various types of glass. The most common type is soda-lime glass, also known as alkaline glass, which is mainly used in the automotive industry, construction industry and household appliances fields. The thickness is generally 1.6to 10mm.Galss with a thickness of 1mm or less 1mm is called borosilicate glass or non-alkaline glass and is mainly used in the field of flat panel monitors and electronic products.

Glass is characterized by hard brittleness, which brings great difficulties to processing. The traditional glass cutting uses carbide or diamond cutting tools. The cutting process is generally as follows: first use a diamond tip or carbide grinding wheel or high hardness metal wheel to draw a nick on the surface of the glass,and then use mechanical means to split the glass along the score line.

During the scribe on the glass with a grinding wheel or a mechanical wheel, tangential tension along the cutting direction is generated so that the glass can be cracked along the scratches.The result of this method of cutting is that the edges are not smooth, there are tiny cracks, residual asymmetric edge stress and residual debris on the material, etc. For many applications, tiny cracks caused by debris and local stresses will cause device failure, so the edges must be polished and polished to strengthen the edges.In addition, an auxiliary agent is also needed to assist the cutting in the processing of the mechanical wheel, and the auxiliary agent may also be stuck on the edge of the finished product, and it needs to be treated by water cleaning or ultrasonic cleaning and other treatment. Subsequent processing operations and low yields (indeterminate cracks) will increase the cost of finished glass products.

Nowadays, the quality requirements for glass products are getting higher and higher, and more precise and detailed processing results must be achieved.

Because the traditional process has been difficult to meet the requirements of microcracks and edge quality, therefore, technological innovation of glass cutting is urgently needed. The laser cutting technology has matured, and it has been successfully applied in the cutting of materials such as sheet metal and pipe, organic sheet and pipe, which has greatly transformed and upgraded the traditional manufacturing technology.
The glass is an inorganic material and its heat conductivity is very low. Theoretically speaking, laser processing should have better results.This also has led to the development of laser cutting glass technology.
The method of laser cutting glass can be divided into two kinds in principle:one is the melting (evaporation) cutting method, and the other is the crack control method. (1)Melt cutting method, using glass at a softening temperature with good plasticity and ductility, with a focused CO2 laser or ultraviolet laser irradiation on the softened glass surface,the higher energy density of the laser leads to glass Melt and then blow away the molten glass with a stream of air, creating a groove to achieve a melt cut of the glass.
(2)Crack control method, which is a common laser cutting method. In the first step, the surface of the glass is heated by a laser, the higher energy will cause the temperature to rise dramatically, and the surface of thr glass will produce a large compressive stress. But the compressive stress will not cause the glass to break. In the second step, The area undergoes rapid cooling, typically using a cooling gas or a cooling fluid. A sharp temperature drop causes a large temperature gradient and a large tensile stress on the glass surface.This tensile stress causes the glass surface to start cracking along a predetermined scribe line to achieve the cutting of glass.

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