Ceramic cutting tools are characterized by high hardness, excellent wear resistance, good thermal stability, and chemical stability, and they do not easily adhere to metals. They hold a very important position in CNC machining and have become one of the main cutting tools for high-speed cutting and machining of difficult-to-process materials. Ceramic tools are widely used in high-speed cutting, dry cutting, hard cutting, and machining of difficult-to-process materials. They can efficiently machine high-hardness materials that traditional tools cannot process at all, achieving "turning instead of grinding"; the optimal cutting speed of ceramic tools can be 2 to 10 times higher than that of cemented carbide tools, thus greatly improving the efficiency of cutting and machining production. The main raw materials of ceramic tool materials are the most abundant elements in the Earth's crust, so the promotion and application of ceramic tools are of great significance for improving production efficiency, reducing processing costs, and saving strategic precious metals. It will also greatly promote the advancement of cutting technology.
1. Types of Ceramic Tool Materials
The types of ceramic tool materials can generally be divided into three major categories: alumina-based ceramics, silicon nitride-based ceramics, and composite silicon nitride-alumina-based ceramics. Among them, alumina-based and silicon nitride-based ceramic tool materials are the most widely used. The performance of silicon nitride-based ceramics is superior to that of alumina-based ceramics.
2. Performance and Characteristics of Ceramic Tools
The performance characteristics of ceramic tools are as follows:
① High hardness and good wear resistance: Although the hardness of ceramic tools is not as high as PCD and PCBN, it is much higher than that of cemented carbide and high-speed steel tools, reaching 93-95 HRA. Ceramic tools can machine high-hardness materials that are difficult for traditional tools to process and are suitable for high-speed cutting and hard cutting.
② High-temperature resistance and good thermal stability: Ceramic tools can still cut at temperatures above 1200°C. Ceramic tools have excellent high-temperature mechanical properties. Alumina ceramic tools have particularly good oxidation resistance, and the cutting edge can be used continuously even when it is red-hot. Therefore, ceramic tools can achieve dry cutting, thus saving cutting fluid.
③ Good chemical stability: Ceramic tools are not prone to adhesion with metals and have good corrosion resistance and chemical stability, which can reduce the adhesion wear of tools.
④ Low coefficient of friction: Ceramic tools have low affinity with metals and a low coefficient of friction, which can reduce cutting force and cutting temperature.
3. Application of Ceramic Tools
Ceramics are one of the tool materials mainly used for high-speed precision machining and semi-precision machining. Ceramic tools are suitable for cutting various cast irons (gray cast iron, ductile cast iron, malleable cast iron, chilled cast iron, high-alloy wear-resistant cast iron) and steels (carbon structural steel, alloy structural steel, high-strength steel, high-manganese steel, quenched steel, etc.), and can also be used to cut copper alloys, graphite, engineering plastics, and composite materials.
Ceramic tool materials have the problem of low bending strength and poor impact toughness, and are not suitable for cutting under low-speed, impact load conditions.
