The influence of different cutting parameters on the glass edge quality

. The influence of different cutting parameters on the glass edge quality was investigated, including the cutter material, the sharpening angle of the cutting roll, the cutting speed and the load applied to the roll. The results show that there are less defects on the edge of the glass cut by diamond cutter. There is no obvious influence of cutting speed on the glass edge quality. The cutter with a smaller sharpening angle is more applicable for the cutting of thin glass, and the thick glass is more suitable to use a bigger sharpening angle cutter. Higher cutting load is helpful for the breaking of the glass along the cutting line. However, it may cause more defects on the edge and the surface of the glass.


Introduction
There are numerous methods for glass cutting, including cutting with laser beam, waterjet cutting, hot airjet cutting or mechanical cutting with a roll cutter [1]. The most simple and accessible way is the mechanical method, that is, generating a cutting line on the glass surface with a hard-alloy or diamond roll cutter, and then break the glass along the cutting line. The cutting parameters including the material of the roll cutter, sharpening angle of the roll cutter, cutting speed and cutting load have different influence on the glass edge quality. The glass edge can be free of defects with a proper cutting parameter. Otherwise, there can be numerous defects, such as chips, scars and notches on the edge and the surface of the glass [2]. These defects have an obvious influence on the glass strength [3]. Different glass requires different cutting parameters according to the glass property. Thus, it is meaningful to investigate the optimum cutting parameters for glasses with different ingredient and thickness.
In this paper, we take the aluminosilicate and lithium aluminosilicate glass as research object, aiming at researching the influence of different cutting parameters on the glass edge quality. The influence of the material and sharpening angle of the roll cutter, the cutting speed and cutting load are investigated. The edge and the surface of the glass after cutting are observed to estimate the cutting effect.

Experimental procedure
Four different kinds of glass were used in this work, including two kinds of aluminosilicate glass produced by Corning Corporation (New York, U.S.) and Aureavia Hitech Company (Chongqing, China), separately, and two kinds of lithium aluminosilicate glass produced by Aureavia Hi-tech Company (Chongqing, China) and Sichuan Xuhong Optoelectronic Technology Company (Sichuan, China), separately. An electric cutting machine (LDQG-2525) produced by Lidu Glass Machinery Company was used to investigate the influence of cutting parameters on the glass edge quality. The edge and surface morphology were observed with an optical microscopy. Figure 1 shows the glass edge quality dependence of roll cutter materials. Normally used hard alloy and diamond cutter were applied to cut the glass separately. Four different kinds of glass, including two kinds of aluminosilicate glass and two kinds of lithium aluminosilicate glass were chosen to analyze the influence of cutter material on glass edge quality. The difference between the four glasses was also shown in Fig.1. The morphology of the cutting edge and surface was observed with an optical microscopy after cutting. From Fig.1, it can be seen that the glass edges cut with diamond cutter show less defects than that with hard alloy cutter. Different kinds of glass show similar results. The diamond roll cutter is better for reducing the defects on the glass edge and surface.  Figure 2 shows the influence of different cutter angle on the glass edge quality. Diamond roll cutter with three different angle (120°,135°and 150°) were used to cut the glass. Two different thickness (1.8mm and 8.0mm) of glass from Corning Corporation were investigated. The cutting speed and load were fixed to 26m/min and 25N for all the experiments, separately. From Fig.2 (a), it can be seen that the edge is more smoothly with a small cutter angle for the thin glass. However, it shows an opposite trend for the thick glass. Thus, roll cutter with a small angle is more applicable for the cutting of thin glass, and the thick glass is more suitable to use a big angle cutter.  10N, 20N, 30N for the thin glass (1.8mm) and as 35N, 45N, 50N for the thick glass (8.0mm).

Results and discussions
From Fig.3, it can be seen that there is no obvious difference between the edges and surfaces with different cutting speed. The thick glass shows a more roughly edge and bigger defect size than the thin glass. From  Fig.4, it is obvious that the cutting depth and the size of defects both on the edge and surface increasing with the increase of cutting load. It is easier to break the glass along the cutting line with a higher cutting load. However, the edge and surface quality deteriorated with the increasing of cutting load, and lateral cracks formed. It is reported that the defects such as chips and notches on the upper surface have a significant effect on the glass strength. A higher cutting load may result in a lower glass strength [3]. In addition, thick glass needs higher cutting load. Thick glass cannot break along the cutting line when the cutting load is below 35N. This may be attributed to the fact that low cutting load cannot produce sufficient median crack depth [4].

Summary
The influence of different cutting parameters on the glass edge quality was investigated, including the cutter material, the sharpening angle of the cutting roll, the cutting speed and the load applied to the roll. The results show that there are less defects on the edge of the glass cut by diamond cutter. There is no obvious influence of cutting speed on the glass edge quality. The cutter with a smaller sharpening angle is more applicable for the cutting of thin glass, and the thick glass is more suitable to use a bigger sharpening angle cutter. Higher cutting load is helpful for the breaking of the glass along the cutting line. However, it may cause more defects on the edge and the surface of the glass. It is necessary to maintain the optimum cutting parameters in order to accomplish high-quality glass cutting.