Difficult-to-machine materials are difficult to machining because of their relatively poor machinability, such as high hardness and high strength, high plasticity and high toughness, low thermal conductivity, low plasticity, high brittleness, the characteristics of chemical too lively performance caused by cutting process in cutting force, cutting temperature is high, the chip is difficult to control, severe strain hardening and low tool life problems.

(1) heating cutting method
Heating cutting method is A conductive heating cutting, that is, in the workpiece and the tool loop (the workpiece must be conductive) to apply low voltage (about 5 V), high current (about 500 A), so that the cutting area to generate heat. The other is plasma heating cutting, that is, the plasma arc near the edge of the workpiece material heating, hardness, strength, so as to improve the cutting conditions. In recent years, "electric fusion explosion" cutting method has been invented. The charged cutter disc and the processed surface will produce a violent discharge, which will be processed by the surface rapidly melt, blasting away, so as to cut off the residual. The method has high efficiency and is not affected by heat, and is suitable for hard, soft and sticky materials.

(2) low temperature cutting method
Cryogenic cutting method using liquid nitrogen (180 ℃) or liquid CO2 (76 ℃) for cutting fluid, it can decrease the temperature of cutting zone, according to the test, using the main cutting force can be reduced by 20%, the method can reduce the cutting temperature above 300 ℃, and at the same time the devolop tumor disappeared, and improve the quality of the
achined surface, tool life can be improved 2 ~ 3 times,in the
processing of high strength steel, wear-resistant cast iron, stainless steel, titanium alloy.

(3) hawke processing
Hauck energy is a kind of energy processing method. The composite energy of activation energy and impact energy is used to process the metal parts, and the surface of the parts can reach the mirror and realize the innovative energy processing technology. Taking advantage of the cold plasticity of metal at room temperature, the processing method of composite energy on metal surface by using hawke energy can make the surface of metal parts reach more ideal surface roughness requirements. At the same time, it belongs to the processing method that does not remove materials. It can be processed on the premise of ensuring the integrity of the workpiece surface, and ideal controllable compressive stress can be preset to extend the service life of the workpiece. Improve the surface microhardness, wear resistance, fatigue strength and fatigue life of parts; It is suitable for mirror machining of stainless steel, aluminum alloy, copper alloy, titanium alloy, nickel base alloy, etc.

(4) ultra-high speed cutting method
In conventional cutting, increasing cutting speed will reduce tool durability. It is suggested that when the cutting speed increases to a critical value, the cutting temperature reaches the highest value, and then the temperature decreases as the speed continues to increase, and the cutting force also decreases, resulting in higher surface quality. This is the theoretical basis of ultra-high speed cutting. Schools and factories in the United States, Germany and Japan have a lot of practice in this area. They use cemented carbide, ceramic tools to cut steel, cast iron, titanium, aluminum alloy and other materials. This cutting method is often restricted by equipment conditions and cannot be popularized.