Utilizing the high hardness of tungsten carbide and improving its toughness, people use metal bonding agents to bond tungsten carbide together, so that this material has a hardness far exceeding that of high-speed steel. Carbide milling cutters have high hardness, wear resistance, A series of excellent properties such as good strength and toughness, heat resistance and corrosion resistance, especially its high hardness and wear resistance, remain basically unchanged even at a temperature of 500 ℃, and still have a high level at 1000 ℃ hardness. The materials used in cemented carbide are widely used as tool materials, such as turning tools, milling cutters, planers, drills, boring cutters, etc., for cutting cast iron, non-ferrous metals, plastics, chemical fibers, graphite, glass, stone and ordinary steel. It can be used to cut difficult-to-machine materials such as heat-resistant steel, stainless steel, high manganese steel, and tool steel.
Some of the factors that affect the characteristics and applications of cemented carbide milling cutters include:
(1) Challenging workpiece materials. Including alternative metal materials and difficult-to-process alloy materials. The workability of some of these materials is less than 1/4 of steel, and the price of some materials can be as high as hundreds of dollars per pound.
(2) Increasingly complex geometry of workpieces. For example, thin-walled workpieces and aerospace parts with complex shapes.
(3) Large size workpieces. Especially the demand for turbines and various heavy machinery parts is increasing. The high cost per piece of these workpieces puts high demands on the machining of cemented carbide milling cutters.
(4) Increasingly special quality and performance requirements. For example, the requirements for the fatigue strength of the surface of the processed parts.
Analysis of the determinants of the quality of cemented carbide milling cutters:
(1) Hardness and toughness. Cemented carbide milling cutters have unique advantages in both hardness and toughness. Tungsten carbide (WC) itself has a high hardness (more than corundum or alumina), and its hardness rarely decreases when the working temperature rises. However, it lacks sufficient toughness, which is an essential performance for cutting tools. In order to take advantage of the high hardness of tungsten carbide and improve its toughness, people use metal bonding agents to bond tungsten carbide together, so that this material has a hardness far exceeding that of high-speed steel, and at the same time it can withstand most cutting processes. Cutting force. In addition, it can withstand the high cutting temperatures generated by high-speed machining.
Therefore, the suitability of cemented carbide milling cutter performance and specific processing depends to a large extent on the original powdering process.
(2) Pulverizing technology of cemented carbide milling cutter. Tungsten carbide powder is obtained by carburizing tungsten (W) powder. The characteristics of tungsten carbide powder (especially its particle size) mainly depend on the particle size of the raw tungsten powder and the temperature and time of carburizing. Chemical control is also crucial, and the carbon content must be kept constant (close to the theoretical ratio of 6.13% by weight). In order to control the particle size of the powder through subsequent processes, a small amount of vanadium and/or chromium can be added before the carburizing treatment. Different process conditions and different processing uses of cemented carbide milling cutters require specific combinations of tungsten carbide particle size, carbon content, vanadium content and chromium content. Through the changes of these combinations, a variety of different tungsten carbide powders can be produced.
