Comparison And Selection Of Various Cutting Tool Materials

The selection of tool materials should comprehensively consider all factors such as machine tool, tool, workpiece state, cutting parameters, cutting fluid and fixture, as well as the matching between tool materials and workpiece materials, so as to optimize the cutting process.

(1) Comprehensive comparison of mechanical and physical properties of various tool materials

1. Hardness order of tool materials

PCD > PCBN > Al2O3 based ceramics > Si3N4 based ceramics > TiC (N) based cemented carbide > WC based Ultrafine Grain Cemented Carbide > high speed steel (HSS).

2. Order of bending strength of tool materials

HSS > WC based cemented carbide > TiC (N) based cemented carbide > Si3N4 based ceramics > Al2O3 based ceramics > PCD > PCBN.

3. Order of fracture toughness of tool materials

HSS > WC based cemented carbide > TiC (N) based cemented carbide > PCBN > PCD > Si3N4 based ceramics > Al2O3 based ceramics.

4. Heat resistant temperature of various tool materials

The PCD tool is 700~800 ℃;

The PCBN tool is 1200~1500 ℃;

The ceramic tool is 1100~1200 ℃;

The TiC (N) based cemented carbide is 900~1100 ℃;

The WC based ultra-fine grain cemented carbide is 800~900 ℃; 

The HSS is 600~700 ℃.

5. Order of thermal conductivity of various tool materials

PCD > PCBN > WC based cemented carbide > TiC (N) based cemented carbide > HSS > Si3N4 based ceramics > Al2O3 based ceramics.

6. Order of thermal expansion coefficient of various tool materials

HSS > WC based cemented carbide > TiC (N) > Al2O3 based ceramics > PCBN > Si3N4 based ceramics > PCD.

7. Order of thermal vibration resistance of various tool materials

HSS > WC based cemented carbide > Si3N4 based ceramics > PCBN > PCD > TiC (N) based cemented carbide > Al2O3 based ceramics.

8. Anti bonding temperature (with steel parts) of various tool materials

Polycrystalline cubic boron nitride PCBN > ceramics > TiC (N) based cemented carbide > WC based cemented carbide > high speed steel.

9. Anti bonding temperature (with nickel base alloy) of various tool materials

Ceramics > polycrystalline cubic boron nitride PCBN > WC based cemented carbide > polycrystalline diamond PCD > high speed steel.

10. Anti oxidation temperature of various tool materials

Ceramics > polycrystalline cubic boron nitride PCBN > WC based cemented carbide > polycrystalline diamond PCD > high speed steel.

11.Tthe anti diffusion strength of various tool materials (compared with that of steel)

Polycrystalline diamond PCD > Si3N4 based ceramics > polycrystalline cubic boron nitride PCBN > Al2O3 based ceramics.

12. Anti diffusion strength of various tool materials (compared with titanium alloy)

Al2O3 based ceramics > polycrystalline cubic boron nitride PCBN > SiC > Si3N4 based ceramics > polycrystalline diamond PCD.

13. The order of solubility of tool material elements in steel (unhardened) is (1027 ℃)

SiC > Si3N4 based ceramics > WC based cemented carbide > PCBN > TiN > TiC > Al2O3 based ceramics > ZrO2.

(2) Key points of tool material selection

1. Factors to be considered in tool selection

(1) Materials and properties of the workpiece to be processed: metal, non-metal, hardness, stiffness, plasticity, toughness and wear resistance, etc.

(2) Geometric shape of workpiece, machining allowance, technical and economic indexes of parts.

(3) Processing technology category: turning, drilling, milling, boring or rough machining, semi finishing, finishing and ultra finishing.

(4) The cutting amount that the tool can bear.

(5) Auxiliary factors: Operation interruption time, vibration, power fluctuation or sudden interruption, etc.

2. When selecting cutting tool materials, it is necessary to consider their matching with the mechanical and physical properties of the machining object

(1) The mechanical properties of cutting tool material and machining object match.

The mechanical property matching problem between cutting tool and machining object mainly refers to the matching of mechanical property parameters such as strength, toughness and hardness between cutting tool and workpiece material.

The cutting tool materials with different mechanical properties are suitable for machining different workpiece materials.

Workpiece materials with high hardness must be processed with tools with higher hardness.

The hardness of tool materials must be higher than that of workpiece materials.

The hardness of tool materials is generally required to be above 60HRC.

The higher the hardness of the tool material, the better its wear resistance.

(2) The material of the cutting tool matches the physical properties of the machined object.

The physical property matching problem between cutting tool and machining object mainly refers to the matching of physical property parameters such as melting point, elastic modulus, thermal conductivity, thermal expansion coefficient and thermal shock resistance between cutting tool and workpiece material.

Tools with different physical properties (such as high-speed steel tools with high thermal conductivity and low melting point, ceramic tools with high melting point and low thermal expansion, diamond tools with high thermal conductivity and low thermal expansion, etc.) are suitable for processing different workpiece materials.

When machining workpieces with poor thermal conductivity, cutting tool materials with good thermal conductivity should be used, so that cutting heat can be quickly transmitted and cutting temperature can be reduced.

(3) The chemical properties of cutting tool materials and machining objects match.

The chemical property matching problem between cutting tool material and machining object mainly refers to the matching of chemical property parameters such as chemical affinity, chemical reaction, diffusion and dissolution between cutting tool material and workpiece material.

Tools with different components (such as superhard tools, ceramic tools, cemented carbide tools, high-speed steel tools) are suitable for machining different workpiece materials.

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