Application of superhard tools in machining hard and brittle materials (2)

November 23, 2022

Third, the cutting of hardened steel

The CBN-L, cBN-W and diamond composite blade PCD-D are used to turn the hard tool steel T10A (HRC60~63), and -L, -W, -D respectively represent the manufacturer. Tool geometry parameters: g ₀ =0°, g _0l = -20°, b _g = 0.2 mm, k _r = 45°. . r _e = 0.5 mm (CBN), 4 mm (PCD). Cutting amount: a _p = 0.1 mm, f = 0.05 mm / r, V = 84 m / min. The tool wear curve is shown in Figure 1.

The T10A was cut with a cemented carbide YM053 blade and a Si ₃ N ₄ based composite ceramic blade. g ₀ = -8°, g _0l = -20°, b _g = 0.2 mm, k _r = 45°. . r _e =0.5 mm, a _p =O.1 mm, f=0.05 mm/r, V=44 m/min. The tool wear curve is shown in Figure 2.

It can be seen from Fig. 1 and Fig. 2 that the effect of machining hardened steel with CBN composite blade is very good, and the effect of cutting hardened steel with diamond composite blade PCD is very poor. Carbide and ceramic inserts cut T10A at lower cutting speeds (V=44m/min), and tool durability is significantly lower than CBN tools.

Fourth, the cutting of cemented carbide

The diamond cemented carbide YG2O (HRA85) was turned with a diamond composite blade PCD and CBN composite blade. The geometrical parameters of the tool are the same as in Fig. 1. a _p = 0.1 mm, f = 0.05 mm/r, V = 16.4 m/min. The tool wear curve is shown in Figure 3. It can be seen that the cutting of YG20 with PCD and CBN inserts has achieved good results, especially with CBN. Since YG20 contains 20% of Co, which belongs to the iron family, it may have a chemical reaction with the diamond tool, which caused the PCD tool to produce a slightly higher wear rate.

Fifth, the cutting of industrial glass

Industrial glass (SiO ₂ +Na ₂ O+CaO, HV40O-500) was turned with PCD and CBN inserts. The tool geometry is the same as in Figure 1. a _p = 0.1 mm, f = 0.05 mm/r, and V = 38 m/min. The test results are shown in Figure 4. The cutting results are good. And PCD leads.

6. Cutting of engineering ceramics

Al ₂ O ₃ based composite ceramics (HRA88-89) were machined with PCD, TFD and CBN. The tool geometry parameters are the same as in Fig. 1. a _p = 0.1 mm, f = 0.05 mm/r, and V = 38 m/min. The test results are shown in Figure 5. As can be seen from Figure 5, the cutting effect of the diamond boring tool is superior to that of the CBN tool.

Figure 4 Superhard tool turning industrial glass

Figure 5 superhard tool turning engineering ceramics

Seven, conclusion

For cutting high-hardness materials, the tool material must have high hardness and elastic modulus. Superhard materials are very suitable for this, which is a match of mechanical properties.

The tool material should be inert to the material of the workpiece in the chemical building. Otherwise, the wear rate of the tool is high. Therefore, diamond tools are not suitable for cutting iron-based materials, such as hardened steel. This is a match of chemical properties. CBN is the best knife material for fine-cut hardened steel.

Cutting industrial glass and engineering ceramics with diamond tools is also very effective.

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Author:

Ms. SU LAN RONG

E-mail:

susu@cn-tianhui.com

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++86 13396680822

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