2018-05-09 18:42:03

The material for making tools must have high temperature hardness and wear resistance, necessary bending strength, impact toughness and chemical inertness, good technological process (cutting, forging and heat treatment, etc.), which are not easy to deform.

Usually, when the material is of high hardness, the wear resistance is also high, and the impact toughness is high when the bending strength is high. However, the higher the hardness, the lower the flexural strength and impact toughness. Because of its high flexural strength, impact toughness and good machinability, high speed steel is still the most widely used tool material, followed by hard alloy.

Polycrystalline cubic boron nitride (PCBN) is suitable for cutting hard hardened steel and hard cast iron, etc.; polycrystalline diamond is suitable for cutting iron free metals, alloys, plastics and fiberglass, etc.; carbon tool steel and alloy tool steel are now used only as tools, rasp, taps and taps.

Cemented carbide indexable inserts have been coated with titanium carbide, titanium nitride, alumina hard layer or composite hard layer by chemical vapor deposition. The developed physical vapor deposition method can be used not only for cemented carbide tools, but also for high speed steel tools, such as drill bits, hobs, taps and milling cutters. As a barrier that hinders chemical diffusion and heat conduction, the hard coating slows the cutting speed of the cutting tool, and the life of the coated blade is about 1~3 times higher than that of the non coating.

Because of the high temperature, high pressure, high speed, and the parts working in the corrosive fluid medium, more and more difficult materials are used. The automation level of cutting and the requirement of machining precision are becoming higher and higher. In order to adapt to this situation, the direction of tool development will be the development and application of new tool materials; further development of the tool's gas deposition coating technology, the deposition of higher hardness coating on high toughness and high strength matrix, a better solution to the spear shield between the hardness and strength of the tool material and the further development of the transposable cutter junction. It can improve the manufacturing accuracy of cutting tools, reduce the difference of product quality and optimize the use of cutting tools.

Cutting tool materials can be divided into the following categories: high speed steel, cemented carbide, cermet, ceramic, polycrystalline cubic boron nitride and polycrystalline diamond.