Tool Materials—Cemented Carbide
Performance and use
Carbide is the most widely used type of high-speed machining (HSM) tool material. This material is produced through a powder metallurgy process and consists of hard carbide (usually tungsten carbide WC) particles and a softer metal binder. composition. Carbide has high hardness, strength, wear resistance and corrosion resistance. It remains basically unchanged even at a temperature of 500°C. It still has a high hardness at 1000°C and is known as the "industrial tooth". , used to manufacture cutting tools, cutting tools, cobalt tools and wear-resistant parts. It is widely used in the fields of military industry, aerospace, machining, metallurgy, oil drilling, and mining tools. With the development of downstream industries, the demand for cemented carbide market continues to increase. big.
The main components are tungsten carbide (WC) and binder cobalt (Co).
Its brand name is composed of "YG" (the first Chinese pinyin of "hard, cobalt") and the percentage of average cobalt content.
For example, YG8 means that the average WCo=8%, and the rest is tungsten carbide tungsten cobalt carbide.
Generally, tungsten-cobalt alloys are mainly used in: carbide cutting tools, molds and geological and mineral products.
②Tungsten titanium cobalt carbide
The main components are tungsten carbide, titanium carbide (TiC) and cobalt. Its brand consists of "YT" (the prefix of the Chinese pinyin of "hard and titanium") and the average content of titanium carbide.
For example, YT15 means average TiC=15%, and the rest is tungsten titanium cobalt cemented carbide with tungsten carbide and cobalt content.
③Tungsten titanium tantalum (niobium) carbide
The main components are tungsten carbide, titanium carbide, tantalum carbide (or niobium carbide) and cobalt. This type of cemented carbide is also called universal cemented carbide or universal cemented carbide.
Selection of carbide cutting tools
When selecting the angle of the tool, you need to consider the influence of many factors, such as workpiece material, tool material, processing properties (roughing, finishing), etc., and you must make a reasonable choice based on the specific situation. Generally speaking, the tool angle refers to the marked angle used for manufacturing and measurement. During actual work, due to the different installation positions of the tool and changes in the direction of cutting motion, the actual working angle is different from the marked angle, but the difference is usually very small. The materials used to make cutting tools must have high high-temperature hardness and wear resistance, necessary bending strength, impact toughness and chemical inertness, good processability (cutting, forging and heat treatment, etc.), and not easy to deform.
Usually when the hardness of the material is high, the wear resistance is also high; when the flexural strength is high, the impact toughness is also high. But the harder the material, the lower its flexural strength and impact toughness. High-speed steel is still the most widely used tool material in modern times due to its high bending strength, impact toughness, and good machinability, followed by cemented carbide.
Polycrystalline cubic boron nitride is suitable for cutting high-hardness hardened steel and hard cast iron; polycrystalline diamond is suitable for cutting iron-free metals, alloys, plastics and fiberglass; carbon tool steel and alloy tool steel are currently only used Make tools such as files, dies and taps.
Carbide indexable inserts are now coated with titanium carbide, titanium nitride, aluminum oxide hard layer or composite hard layer using chemical vapor deposition method. The developing physical vapor deposition method can be used not only for carbide cutting tools, but also for high-speed steel cutting tools, such as drill bits, hobs, taps and milling cutters. The hard coating acts as a barrier that hinders chemical diffusion and heat conduction, slowing down the wear rate of the tool during cutting. The life of the coated tool is approximately 1 to 3 times longer than that of the uncoated tool.
As parts that work under high temperature, high pressure, high speed, and in corrosive fluid media are used in more and more difficult-to-machine materials, the automation level of cutting processing and the requirements for processing accuracy are getting higher and higher.