Performance index analysis of different tool materials!
July 19, 2022
Selection principle of CNC tool holder materials at present, the widely used CNC tool materials mainly include diamond tools, cubic boron nitride tools, ceramic tools, coated tools, cemented carbide tools and high-speed steel tools. There are many general brands of tool materials, and their performances vary greatly.
The cutting tool materials for CNC machining must be selected according to the workpiece and machining properties. The selection of tool materials should be reasonably matched with the processing object. The matching of cutting tool materials with the processing object mainly refers to the matching of their mechanical properties, physical properties and chemical properties, so as to obtain the longest tool life and the maximum cutting productivity.
Mechanical property matching between cutting tool material and machining object mechanical property matching 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. Tool materials with different mechanical properties are suitable for processing different workpiece materials.
① The hardness order of tool material is: diamond tool > cubic boron nitride tool > ceramic tool > cemented carbide > high speed steel.
② The bending strength order of tool materials is: high speed steel > cemented carbide > Ceramic Tools > diamond and cubic boron nitride tools.
③ The order of toughness of tool materials is: high speed steel > cemented carbide > cubic boron nitride, diamond and ceramic tools.
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, which is generally required to be above 60HRC. The higher the hardness of the tool material, the better its wear resistance. For example, when the cobalt content in cemented carbide increases, its strength and toughness increase, and its hardness decreases, which is suitable for rough machining; When the cobalt content decreases, its hardness and wear resistance increase, which is suitable for finishing.
Tools with excellent high-temperature mechanical properties are especially suitable for high-speed machining. The excellent high temperature performance of ceramic tools enables them to cut at a high speed, and the allowable cutting speed can be 2 ~ 10 times higher than that of cemented carbide.
The cutting tool material matches the physical properties of the processing object. The 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, 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 the cutting heat can be quickly transmitted and the cutting temperature can be reduced. Due to the high thermal conductivity and thermal diffusivity of diamond, the cutting heat is easy to dissipate and will not produce great thermal deformation, which is particularly important for precision machining tools with high dimensional accuracy requirements.
① The heat resistance temperature of various tool materials: diamond tool is 700 ~ 8000C, PCBN tool is 13000 ~ 15000c, ceramic tool is 1100 ~ 12000c, TiC (n) based cemented carbide is 900 ~ 11000C, WC based ultra-fine grain cemented carbide is 800 ~ 9000c, HSS is 600 ~ 7000c.
② The order of thermal conductivity of various tool materials: pcd>pcbn>wc based cemented carbide >tic (n) based cemented carbide >hss>si3n4 based ceramics >a1203 based ceramics.
③ The order of thermal expansion coefficient of various tool materials is: hss>wc based cemented carbide >tic (n) >a1203 based ceramics >pcbn>si3n4 based ceramics >pcd.
④ The order of thermal shock resistance of various tool materials is: hss>wc based cemented carbide >si3n4 based ceramics >pcbn>pcd>tic (n) based cemented carbide >a1203 based ceramics.
Chemical property matching between cutting tool material and machining object the chemical property matching 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 tool material and workpiece material. Different cutting tools with different materials are suitable for processing different workpiece materials.
① The anti bonding temperature of various tool materials (with steel) is: PCBN > ceramics > cemented carbide >hss.
② The oxidation resistance temperature of various tool materials is: ceramics >pcbn> cemented carbide > diamond >hss.
③ The diffusion strength of three cutting tool materials (for steel) is: Diamond >si3n4 based ceramics >pcbn>a1203 based ceramics. The diffusion strength (for titanium) is: A1203 based ceramics >pcbn>sic>si3n4> diamond.
Reasonable selection of NC tool materials generally speaking, PCBN, ceramic tools, coated cemented carbide and TiCN based cemented carbide tools are suitable for NC machining of ferrous metals such as steel; PCD cutting tools are suitable for processing non-ferrous metal materials such as Al, Mg, Cu and their alloys and non-metallic materials.
