Why You Should Not Go to New Ceramic Tool Materials?
Home › Product News › Why You Should Not Go to New Ceramic Tool Materials?
Why You Should Not Go to New Ceramic Tool Materials?
The emergence of new ceramic cutting tools is the result of a technological revolution in the first human revolution in the use of ceramic materials to reform mechanical cutting.
Ceramic materials have become a new generation of cutting tool materials due to their high hardness and high temperature resistance. In the early 20th century, Germany and the United Kingdom have begun to seek to replace traditional carbon tool steel tools with ceramic tools, but ceramics are also known by their people. Brittleness is limited, so how to overcome the brittleness of ceramic tool materials and improve its toughness has become the main topic of ceramic tool research in the past 100 years. The application range of ceramics is also expanding.
The Main Reasons for the Efforts of the Engineering Technology Community to Develop and Promote Ceramic Tools:
- It can greatly improve production efficiency;
- It is determined by the global depletion of tungsten resources, the main components of high-speed steel and cemented carbide.
In the early 1980s, it was estimated that the proven tungsten resources in the world would only be sufficient for 50 years. Tungsten is the most scarce resource in the world, but its consumption in cutting tool materials is very large, which leads to the rising price of tungsten ore, which has increased many times in decades. This has also promoted the development of ceramic tools to a certain extent. Popularization, research and development of ceramic tool materials have achieved remarkable results.
So far, the materials used as ceramic cutters have formed alumina ceramics, alumina-metal ceramics, alumina-carbide ceramics, alumina-carbide cermets, alumina-nitride cermets and the latest successful research Boron nitride ceramic tool.
The United States has always been the world leader in the development of oxide-carbide-nitride ceramic tools. As far as the world is concerned, German ceramic tools have been used not only for ordinary machine tools, but also as an efficient, stable and reliable tool In CNC machine tool processing and automated production lines. Japanese ceramic blades have reached the international advanced level in product variety, output and quality.
The Development and Application of Ceramic Tools in China Have Also Achieved Many Significant Results:
①Alumina ceramic cutting tools: pure Al2O3 ceramics and ceramic materials mainly based on Al2O3 and added with a small amount of other elements, such as MgO, NiO, SiO2, TiO2 and Cr2O3, are used. The additive is beneficial to strengthen the bending strength of Al2O3, but the high temperature performance is reduced, so it is better to use pure alumina ceramic material.
The room-temperature hardness and high-temperature hardness of Al2O3 ceramics are higher than those of cemented carbide materials. Although the bending strength of Al2O3 ceramics at room temperature is low, with the increase of temperature in use, its bending strength is less reduced. According to this characteristic, it is quite suitable for high-speed cutting. Al2O3 ceramics have good compressive strength at room temperature and high temperature, especially to overcome the shortcomings of deformation and collapse of common high-speed steel tools and carbide cutting edges.
In addition, Al2O3 ceramics can show their talents in terms of physical thermal properties, oxidation resistance, resistance to adhesion and chemical inertness. However, alumina ceramic tools are more prone to bond wear and notch wear when cutting iron alloys and steel parts.
As the tool material with the longest history, alumina ceramic tools are most suitable for high-speed cutting of hard and brittle metal materials, such as chilled cast iron or hardened steel; for cutting large mechanical parts and for cutting high-precision parts Processing. Alumina ceramic cutters are less effective in the intermittent cutting of short and small parts, steel parts, and the cutting of single materials such as Mg, Al, Ti, and Be, and their alloy materials. It is easy to cause diffusion wear or spalling and chipping of the cutter. Such defects are its flaws.
②Alumina-carbide-based ceramics: A certain proportion of carbides, such as Mo2C, WC, TiC, TaC, NbC, and Cr3C2, are added to Al2O3 ceramics to improve the performance of Al2O3 ceramic tools. When the TiC content is 30%, the durability of ceramic tools is significantly improved, and the depth of thermal cracks is also small. At present, the production of hot-pressed Al2O3-TiC ceramic cutting tools adopts this formula. The bending strength and thermal shock resistance of Al2O3-TiC ceramics are better than Al2O3 ceramic tools.
③Alumina-metal ceramics: In order to improve the toughness of Al2O3 ceramic cutters, less than 10% of Cr, Co, Mo, W, Ti, Fe and other metal elements are introduced into the material to form Al2O3 cermet. In this way, the density, flexural strength and hardness of the material are improved, but because of the low creep strength and poor oxygen resistance of the alumina-cermet cutting tool, it has been poorly popularized.
④Alumina-carbide cermet tool: It is made of Al2O3-TiC ceramic material, which is made of Mo, Ni (or CO, W) and other metals as the bonding phase by hot pressing.
Because the metal-bonded Al2O3 grains and the carbide grains intersect each other, they have a high joint strength, so they form good cutting performance. This type of ceramic tool is most suitable for processing hardened steel, alloy steel, manganese steel, chilled cast iron, cast steel, nickel-based or nickel-chromium alloy, nickel-based and cobalt-based alloy, etc. It can also be used for non-metallic materials such as fiber glass , Cutting of plastic interlayer and ceramic materials. Because alumina-carbide cermet has good thermal shock resistance, it can be used for milling, planing, repeated short-term cutting or other intermittent cutting, etc., or wet cutting with cutting fluid.
⑤ Boron nitride ceramic tool: Recently, Sumitomo Electric Company of Japan has developed a ceramic tool material with higher hardness—adhesive cubic crystal boron nitride ceramic (CBN) sintered body. The sintered material is made after sintering for 10 minutes at a pressure of 7-8 GPa, at ultra-high temperature, and high pressure of 2,300°C to 2,400°C. This technology also includes unique software technology such as grinding fine powder diameter to improve the purity of CBN in the raw material preparation stage. The sintered boron nitride ceramic material with a CBN content of 100% was developed by combining particles with a particle size below 0.5mm.
⑥Alumina-nitride cermet: The basic performance and processing range of this ceramic tool material is equivalent to that of Al2O3-carbide cermet material, but because nitride replaces carbide, it has better thermal shock resistance and more Suitable for intermittent cutting. However, its flexural strength and hardness are lower than those of TiC-added cermets, and its research and further development are continuing.
Ceramic cutting tools made of boron nitride materials will not cause common thermal cracking and chipping when cutting hard cast iron. According to different conditions, compared with the CBN sintered body containing other bonding materials, the use time of boron nitride ceramic tools can be extended more than 10 times, becoming a material that can be cut intermittently. Especially in the automotive industry, the hBN sintered body has a wide range of applications in machining as a cutting material that can process hard materials such as engines and cast iron.
The previous sintered body contains a particle binder, so it cannot form unique properties such as high hardness and thermal conductivity like CBN. For example, CBN direct conversion technology is not suitable for high-speed cutting tools because of its coarse particle size.
All in all, with the continuous deepening of research and development and development of special ceramic materials, the application proportion of ceramic tools in the metal cutting processing industry continues to expand. With the development requirements of the aviation and aerospace industries, it is necessary to meet the requirements for improving the cutting efficiency of workpiece materials such as Ti alloys and Ni-based superalloys, and special ceramic tool materials will make greater contributions.
Write a Comment