Common tool wear patterns in cutting, usually appear the following three forms: the first is due to mechanical wear, such as chipping edge or abrasive wear.
The second wear due to the cutting heat, such as bonding, diffusion, etc.
The third is due to chemical factors caused by the softening of the cutting edge, melting and resulting in breaking, thermal fatigue, thermal cracking, etc.
(1) Causes of mechanical wear
Tool wear occurs in a very short time when cutting difficult-to-machined materials, because there are many factors promoting tool wear in the machined materials. Most difficult-to-machined materials have low thermal conductivity. As a result, the bond strength of the binder in the tool material decreases at high temperatures, thus accelerating tool wear.
(2) Wear caused by cutting heat
When cutting materials with high hardness and toughness, the temperature of the cutting edge is very high, and the tool wear is similar to that when cutting difficult materials. Especially when machining workpiece materials with short chips, there will be crescent depression wear near the cutting edge, often in a short time that the tool damage.
(3) Wear caused by chemical factors
The components in the difficult to process materials and some components in the tool materials react under high temperature cutting conditions, and the components precipitate, fall off, or generate other compounds, which will accelerate the formation of tool wear phenomenon such as cutting edge.
Performance requirements for cutting tools
The metal cutting tool materials used today vary from HSS, which has the lowest cutting speed and least wear resistance, to POLYcrystalline diamond, which has the best high speed performance.
2) Impact resistance has good impact resistance toughness, in addition, the high speed cutting tool also has high thermal hardness and chemical stability.
3) The service life of the coating material with good heat resistance and high hardness and multi-layer coating technology, so that the cutting range of coated carbide tool is large and the service life is long.
Commonly used tool materials
1) Alloy tool steel has high thermal hardness but low price, and is commonly used to manufacture low-speed tools with complex shapes, such as reamers, taps and die.
(2) High speed tool steel
Its high temperature hardness and wear resistance are better than alloy tool steel. Because of its good heat treatment performance, high strength and good grinding, it is widely used in the manufacture of forming turning tool, milling cutter, drill and broach and other machine tools.
(3) Hard alloy
It is an alloy made of tungsten carbide, titanium carbide and cobalt by powder metallurgy. Cemented carbide blade is usually fixed on the tool body. At present, cemented carbide has become one of the main tool materials.
In order to prevent tool wear too fast, special cutting fluid should be selected, with the following advantages:
(1) Improve the process accuracy of the special cutting fluid containing vulcanized extreme pressure antiwear additives, can effectively protect the tool, improve the process accuracy.
(2) In line with the process requirements special cutting fluid in the viscosity, flash point, pour point, thermal conductivity and other aspects of the test, to meet the needs of various cutting processes.
(3) Good environmental performance special cutting fluid compared with lai seed oil, mechanical oil, recycled oil, has good stability, will not harm the equipment, human body, environment.
---EDITOR: Doris Hu
---POST: Doris Hu
