Cutting of Ceramic Materials

The cutting characteristics of ceramic materials are significantly different from those of metal materials. In the cutting process of metal materials, the main cutting force Fc is the largest among the three cutting components, while in the cutting process of ceramic materials, the back force Fp is the largest. This is mainly due to the material characteristics of ceramic materials themselves, which increases the difficulty of machining ceramic materials.

1. Tool wear

In the cutting process of ceramics, tool wear is the most obvious feature. Due to the fact that ceramic materials rarely undergo plastic deformation during the cutting process, the main wear of the cutting tool is on the back face, while the wear on the front face is minimal. At the same time, the bending state of the cutting tool is influenced by factors such as the tool material, tool shape, cutting amount, coolant, and the performance of the ceramic material itself.

(1) Al203 ceramics

The ratio of ionic bond to Covalent bond of Al203 ceramics is about 6:4, and the dislocation distribution density is small, so it is difficult to produce plastic deformation.

(2) Si3N4 ceramics

The ratio of ionic bond to Covalent bond of Si3N4 ceramics is about 3:7. Because of strong anisotropy, few atomic slip planes, unlimited slip direction, it is difficult to deform, even at high temperatures.

(3) Zr02 ceramic

The ratio of ionic bond to Covalent bond of Zr02 ceramics is about 7:3, which is easy to produce shear slip deformation and has high toughness.

(4) SiC ceramics

The ratio of ionic bond to Covalent bond of SiC ceramics is about 1:9. Because of strong anisotropy, atoms are not easy to slip at high temperature, so cutting is more difficult.

2. Cutting force

In general, unlike the continuous cutting generated during metal cutting, the cutting process of ceramic materials is dominated by brittle collapse. Through cutting ceramic materials such as AI203, Si3N4, Zr02 and SiC, it is found that the main cutting force Fc is not the largest among the three cutting forces, and the back force Fp is the largest, which is also the common feature of cutting hard and brittle materials. The reason is that when cutting hard and brittle materials, the Hardness is high, The cutting edge of a tool is difficult to cut people. At the same time, this is also similar to the fact that the normal grinding force is much greater than the tangential grinding force during the grinding process of ceramic materials.

3. Cutting temperature

At present, there is relatively little research on the cutting temperature of ceramic materials. Some scholars studied the cutting temperature of Cordierite ceramic materials with diamond tools, and found that the cutting temperature of Cordierite ceramic materials increased with the increase of cutting speed. When the cutting speed is 80m/min, the dry cutting temperature of Cordierite ceramic material is about 700 ℃, which is significantly higher than the cutting temperature under cooling conditions. Obviously, the cutting temperature of Cordierite ceramic material can be reduced under the condition of low speed cutting and increasing coolant, thus effectively reducing the wear of diamond tools.

4. Cutting parameters

Most ceramic materials are mainly removed through brittle fracture, so there will be residual machining cracks on the machined surface of ceramic materials, greatly reducing the strength of ceramic parts. When cutting ceramic materials, the influence of cutting parameters (cutting speed, cutting depth, and feed rate) on the surface roughness of the machined surface also varies depending on the ceramic material.

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