Special tool materials for CNC lathes in China Machine Tool Works

Special tool materials for CNC lathes in China Machine Tool Works

(1) Ceramic knives. Ceramic tool materials are mainly composed of oxides and nitrides such as A12O3 and Si3N4 with high hardness and melting point, and a small amount of metal carbides, oxides and other additives, which are pressed and sintered by powder metallurgy technology. There are two kinds of commonly used ceramic knives: A1203 tomb ceramics and Si3N4-based ceramics.
The advantage of ceramic tools is that they have high hardness and wear resistance, with a hardness of 91-95HRA. The wear resistance is 5 times that of cemented carbide: the tool life is higher than that of cemented carbide: it has good thermal hardness, when cutting When the overflow reaches 760°C, it has a hardness of 87HRA (equivalent to 66HRC) and the temperature reaches 1200°C. It can still maintain the hardness of 80HRA; the friction coefficient is low, and the cutting force is smaller than that of cemented carbide. When this type of tool is used, the surface finish of the workpiece can be improved.
Because the shortcoming of ceramics is brittleness, the strength and toughness of ceramic knives are poor, and the thermal conductivity is low. This type of tool is generally used for high-speed fine machining of hard materials.
(2) Diamond tools. Diamond has extremely high hardness. There are three types of diamond knives currently in use: natural diamond knives: synthetic polycrystalline diamond knives: composite polycrystalline diamond knives.
The advantages of diamond tools are: extremely high hardness and group resistance. The microhardness of synthetic diamond is 1000OHV, and the wear resistance is 60-80 times that of cemented carbide; the cutting edge is sharp, which can achieve ultra-precision micro-processing and mirror surface Processing; has high thermal conductivity.
The disadvantages of diamond tools are: poor heat resistance, low strength, and high brittleness. Very sensitive to vibration.
This type of tool is mainly used for fine processing of non-ferrous metals and their alloys and non-metallic materials under high-speed conditions.
(3) Cubic nitriding stretch tool Cubic boron nitride (CBN for short) is synthesized from hexagonal boron nitride under high temperature and high pressure.
The main advantages of CBN tools are high hardness, which is second only to diamond, good thermal stability, high thermal conductivity and small friction coefficient. The disadvantage is that the strength and toughness are poor, and the bending strength is only 1/5-1/2 of that of ceramic tools.
CBN tools are suitable for processing high-hardness hardened iron, chilled cast iron and high-temperature alloy materials. It is not suitable for processing steel and nickel-based alloys with large plasticity, nor is it suitable for processing aluminum alloys and steel alloys. High-speed cutting with negative rake angles is usually adopted.