Cermet is a heterogeneous composite material composed of metal or alloy and one or several ceramic phases, in which the latter accounts for about 15% ~ 85% (volume).
At the same time, the solubility between metal and ceramic phases is quite small at the preparation temperature.
The TiC (N) – based cemented carbide of cermet (TiC (TiN) – WC + Ni (Mo) + Mo2C) used for manufacturing cutting tools is a cemented carbide material with TiC (ceramic) as the matrix (sometimes other carbides and nitrides are added) and Ni, Mo or Co (metal) as the binder (usually containing 10% ~ 20% of the binder).
1. Classification and characteristics of cermet cutting tool materials
TiC (N) based cemented carbide has high hardness (90 ~ 94HRA), which almost reaches the level of ceramics, so it is also called “cermet” (see Fig. 2-17).
In particular, the bonding temperature between TiC (N) and steel is high, so the resistance to crater wear is very good.
Its biggest advantage is that the affinity between its material and the processed material is very low, so it is not easy to produce knife sticking and chip accumulation, so that the processed surface is very smooth and flat.
Its tool life is several times longer than that of WC based cemented carbide.
However, the bending strength and toughness are worse than WC based cemented carbide, and the plastic deformation resistance and edge collapse resistance are poor.
Therefore, it is mainly used for high-speed finishing or semi finishing of carbon steel, stainless steel and nodular cast iron, which is not suitable for heavy cutting and intermittent cutting.
By adding WC, TaC, TiN, TaN and other carbides, the flexural strength and toughness can reach the level of WC based cemented carbide.
The characteristics of cermets are summarized as follows:
(1) Low density, higher hardness and thermal hardness than WC based cemented carbide.
(2) Strong wear resistance and crescent pit wear resistance.
(3) Good chemical stability and oxidation resistance.
(4) The affinity with the workpiece material is small, the friction coefficient to the steel is small, and it is not easy to stick the knife and accumulate chips.
(5) The coefficient of thermal expansion is higher than that of WC based cemented carbide.
Fig. 2-17 cermet blade
Cermet is a kind of tool material suitable for finish machining, which can ensure better dimensional accuracy and surface roughness.
Cermets are mainly used in the processing of long chip materials such as steel materials.
At present, they have been used to process materials such as cast iron and stainless steel.
The key point of using cermet tools is to select the appropriate blade shape, tip radius and groove shape (the optimal combination of material and geometry).
In order to obtain the best productivity and safety, the feed rate should be increased as much as possible and the back cutting depth should be minimized as much as possible.
2. Brand, performance and application of cermet materials
（1） Brand and application of domestic cermet materials
1. Zhuzhou Diamond
The properties and applications of some cermets of Zhuzhou Diamond are shown in table 2-20.
Table 2-20 properties and applications of some cermets of Zhuzhou Diamond
|Grade||Performance and Application|
|YNO1||High wear resistance, good oxidation resistance, allowing high cutting speed.It is suitable for finishing of alloy steels such as carbon steel, chromium, manganese and silicon steel.|
|YN05||Good hardness and heat resistance, wear resistance close to ceramics, good thermal stability, excellent oxidation resistance and poor impact resistance.It is suitable for high-speed finishing of alloy steel, quenched steel, cast iron and alloy cast iron.|
|YN10||It has good wear resistance and heat resistance, the hardness is equivalent to P01, and the strength is higher than P01. It is suitable for continuous finishing of carbon steel, alloy steel, stainless steel, quenched steel and other materials.|
|YN15||Good wear resistance, high strength and toughness.It is suitable for finishing and semi finishing of general steel.|
|TNO5||It is suitable for high-speed finishing of carbon steel, cast steel, alloy steel, stainless steel, tool steel and hardened steel.|
|TN10||It is suitable for finishing of carbon structural steel, medium carbon quenched and tempered steel, high-strength steel, stainless steel and heat-resistant alloy steel. It can also be used for finishing and semi finishing of hardened steel with hardness less than 55HRC.Especially for high-strength steel and stainless steel, the semi finishing effect is the best.|
|TN10.1||Universal turning brand, suitable for continuous cutting of all kinds of cast steel, alloy steel, stainless steel and high strength steel.|
|TN10.2||Universal milling brand, suitable for continuous cutting of all kinds of cast copper, alloy steel, stainless steel and high strength steel.|
|TN20||It is suitable for semi finishing of alloy steel, stainless steel and high strength steel.Under certain conditions, it can be used for finishing and semi finishing of nodular cast iron and gray cast iron.|
|TN30||It is suitable for high-speed finish milling of alloy steel, stainless steel, high-strength steel and nodular cast iron. It can also be used for turning of this kind of materials.|
（2） Foreign brand of cermet cutting tools
The brand of foreign cermet cutting tools is shown in Appendix B.
Appendix B brand of foreign cermet cutting tools
|ISO||seco||Sandvik croman||Kenner metal||Iska||Mitsubishi||sumitomo||Tungaloy||Kyocera||Teguk||Hitachi||Chloe||Daijie||Japanese special ceramics||Ingersoll||Widia||Walter||Senra Tianshi|
（3） Typical product introduction
Tp1020 and TP1030 are the latest cermet blades of shangao (see Fig. 2-18).
Among them, TP1020 is a high wear-resistant cermet material grade with the best predictable surface roughness.
It is preferred for steel and stainless steel processing.
TP1030 is a high wear-resistant cermet material grade of coating, which is mainly applicable to the processing of steel parts and stainless steel with high requirements for surface roughness and productivity.
Fig. 2-18 shangao cermet blade