1 Introduction
1.1 Introduction of diamond cut off wheel for glass
1.2 Introduction of quartz glass
2 Test and comparison
2.1 Machine tool parameters:
2.2 Condition parameters of cutting test
2.3 Test results
2.3.1 Cutting force features
2.3.2 Cutting force ratio features
2.3.3 Cutting slot features
3 Conclusions
1 Introduction
1.1 Introduction of diamond cut off wheel for glass
Metal bond and resin bond diamond cut-off wheels
Resin bond has good self-sharpening, cutting sharp and good elasticity, the good surface quality of the workpiece.
Metal bond has strong holding for abrasive grain, good wear resistance and good shape retention for cut off wheel.
1.2 Introduction of quartz glass
Quartz glass features high-temperature resistance, corrosion resistance, good thermal stability, and good transmittance. It is widely used in electric light source, semiconductor and etc. such as high-pressure mercury lamp, the long arc xenon lamp, infrared image, the prisms and lens of the spectrograph, reflection window of a large astronomical telescope, etc.
Quartz glass is a typical hard and brittle material with high hardness, low fracture toughness and difficult to machine. There are cold machining and hot machining in view of the machining methods. Cold machining mainly includes cutting, grinding and polishing. It takes much time to eliminate the cracks left by grinding and polishing.
Basic Physical Property of Quarts Glass
| Modulus of Elasticity /GPa | Shear Modulus/GPa | Poisson Ratio | Mons’ Hardness Scale |
| 77.8 | 34.1 | 0.17 | 6-7 |
Therefore, it is necessary to choose a suitable diamond cut off wheel for a glass to improve the efficiency and accuracy of processing quartz glass.
2 Test and comparison of diamond cut off wheel for glass
2.1 Machine tool parameters:
Test in the vertical machining center, the radial accuracy of feed and spindle is 1μm.The
Vertical force Fv and horizontal force Fh by Kistler 9257B, and put the data into the high dynamic data acquisition system. The device is shown below.
2.2 Condition parameters of cutting test
| Name | Material or Value |
| Bond type | Metal, Resin |
| Wheel size/mm | φ50、Thickness 0.3 |
| Wheel abrasive grain | 600# Diamond，Concentration25% |
| Workpiece | Quartz glass |
| Stone | 1000# Silicon carbide |
| Wheel rev n/(r/m) | 3000、5000、8000 |
| Feed speed vw/(mm/min) | 400、600、1200 |
| Cutting depth ap /μm | 20、40、60、80 |
2.3 Test results
2.3.1 Cutting force features
According to the corresponding calculation formula, the relationship between the cutting force Fv and Fh and the theoretical direction force Fn and tangential force Ft is as follows: Fv≈Fn，Fh≈Ft.
The various features of cutting force parameters are as follows: With the increase of cutting depth or feed speed, the normal force and tangential force increases. With the increase of cut off wheel speed, the normal force and tangential force decreases.
Variation features of cutting force
In addition, the normal force and tangential force of resin cut off wheel for quartz glass is smaller than those of metal cut-off wheel. This is because resin cut off wheel has good self-sharpening and high edge in the cutting process.
When the material removal rate is constant, the cutting depth increases, the feed speed decreases, and the cutting force increases.
The cutting force increases with the increase of cutting depth and feed speed, and the influence of cutting depth on cutting force is larger than that of feed speed on cutting force.
In the actual cutting process, using small cutting depth, large feed and high speed can reduce the cutting force, prolong the life of cut off wheel and improve the cutting quality of the workpiece under the condition of the machine tool running smoothly.
2.3.2 Cutting force ratio features
Cutting force ratio Fn/Ft refers the degree of difficulty of abrasive grains pressed into the workpiece materials when cutting, which is related to the physical features of cutting materials and the cutting edge of abrasive grains. The larger the force ratio in the process of machining, and the workpiece material removal is close to the mode of brittle fracture.
The following figure shows the cutting force ratio features of 12 points of resin cut-off wheel and metal cut-off wheel at Rev. 3000r/min, cutting depth of 20-80 um, a feed speed of 400-1200 mm/min.
From the diagram, it can be seen the force ratio of resin cut off wheel for quartz glass is larger than that of metal cut-off wheel. The reason is that the resin cut off wheel has the high grinding edge, and the cutting effect of the abrasive is that the workpiece with a relatively large normal force is pressed and the material with a relatively small tangential force is removed. And the force ratio of 2 kinds of cut off wheel for quartz glass is between 2.11 and 2.46. While the cutting force ratio of diamond saw blade for granite is 2.2-8.5, and the cutting force ratio of electroplated diamond cut off wheel for igneous rock is 2.78-3.03, and the cutting force ratio of resin bond diamond cut off wheel for carbide is 1.96-2.22.
2.3.3 Cutting slot features
Cutting the slot of quartz glass is easy to obvious chip. And when the cutting depth is small, the feed speed is small and the Rev. is large, it can also chip. The reason is that when cut off wheel cutting into the workpiece, the impact of abrasive grains on the workpiece is strong, and the material is fall off by brittle fracture but it cannot eliminate the chips left when cut off wheel cut into the workpiece. The 2 kinds of a cut-off wheel for cutting quartz glass under the different parameters can chip when cutting slot, but the cutting slot quality of resin cut off wheel is relatively good.
3 Conclusions of diamond cut off wheel for glass
According to the above testing, it is concluded that resin bond cut off wheel is sharper than the metal bond cut-off wheel, but the wear resistance of metal bond diamond cut off wheel for glass is better.
If you are equally interested in cutting ceramics, please read How to choose diamond cut off wheel for industrial ceramic (aluminum oxide, silicon nitride) 2019