The degradation of blade performance begins the moment the aero engine starts! The extreme friction between the rapidly rotating blades and the air can generate temperatures of hundreds of degrees. However, the rough particles on the surface of the blade will be further eroded by friction and collision, rapidly expanding the original surface defects. At the same time, the clearance between blade tip, casing and hub will further increase under the triple factors of friction, corrosion and thermal fatigue.

The "heart" of an airplane is the engine and the core component of the engine is the blade. Because the engine needs to complete the compression and expansion of gas in the process of pushing the aircraft forward, the processing of this process is to complete the blade. The position of blade is the most severe environment, the most complex stress and the highest temperature. Aero engine design is complex, machining accuracy and reliability are required.

Aeroengine blade is a rigid part with complex curved surface, which is difficult to be machined, machined and technically.

Titanium alloy and nickel-based superalloy are mainly used for aero-engine blades, which are typical thin-walled weak rigid parts with large blade twist Angle and high profile accuracy. In addition, in order to ensure the performance of aero-engine, some aero-engine blades need to be very thin, and the lowest point of some aero-engine blades is only 0.8mm, especially for the blade part at the edge of the intake and exhaust, the processing quality is higher and the size is smaller. All these characteristics bring great difficulty to the machining of aero-engine blade. Blade material characteristics and size determine it can withstand the mechanical processing of external force is limited, once its role in the cutting force in milling is too large, will cause the blade to produce elastic deformation, is we often say "knife" phenomenon, resulting in the theory of aeroengine blades machining accuracy and produce certain deviation between the actual machining precision, affecting the processing of the blade recision.

In addition, the blade material used by its ability to resist plastic deformation is strong, and it also has strong wear resistance, high temperature resistant properties, which result in the mechanical machining of blade performance is poorer, strong wear resistance will increase blade cutting tool wear in cutting speed, leading to a worn tool in use after a period of time, need many times in processing cutting tool parameter calibration, such as If not calibrated, "let the blade" deformation error will occur. This problem is particularly obvious in the processing of blade tip, inlet and exhaust edge and other parts with poor rigidity. The elastic deformation level after mechanical processing is serious, which greatly affects the processing quality of blade.

In the cutting process, improving the speed and speed of the cutting tool can effectively improve the blade surface finish and surface quality. Milling process by dry cut in a short period of time is cut, the vast majority of cutting heat is chip away, reduce the thermal deformation of the workpiece, secondly, in processing, because the cutting layer material softening part of the reduction, also can reduce the deformation of parts processing, is conducive to ensure the size of parts, shape accuracy. In addition, the use of cutting fluid will be able to effectively reduce the friction in the cutting process and reduce the cutting temperature, reduce the thermal stress inside the blade, reasonable use of cutting fluid to improve the tool durability and processing surface quality, processing box degree has an important role. In the process of selecting cutting fluid, it is necessary to consider the characteristics of cutting fluid, the material of blade and the amount of heat and chip in processing, so as to reasonably determine the flow of cutting fluid. Therefore, in order to prevent the deformation of parts in processing, sufficient cutting fluid must be reasonably used. The machining allowance distribution is used to adjust the machining process and enhance the machining rigidity of blade. It is also one of the effective means to control the machining deformation of blades by increasing the rigidity through technological means.

Blade polishing technology mainly includes grinding wheel and abrasive flow polishing. The application of super hard abrasive artificial diamond and CBN wheel improves the grinding accuracy and efficiency continuously, and the application range of grinding is expanding day by day. Superabrasive grinding wheel has the advantages of low surface roughness Ra value, low heating and not easy to burn workpiece, especially suitable for precise and efficient processing of blade parts.

When the blade profile accuracy is about 0.025mm and the blade surface roughness Ra decreases from 3.1μm to 0.51μm, the engine efficiency can be improved by 3%~6% around the design value. 

Now the general flow of aircraft engines using titanium alloy and nickel based superalloy, its material has strong resistance to high, grinding performance. Modern superhard grinding technology adopted by the abrasive grinding wheel can fix some effects on the blade surface, to complete the meter by means of grinding processing, high speed way of grinding with grinding ability is strong, good wear resistance, high durability, small grinding force, low grinding temperature, the characteristics of small grinding stress, in the role of low temperature could effectively reduce the blade mechanical stress and thermal stress, reduce the deformation of the blade At the same time, grinding machining internal stress is small, no burn, crack and other defects can effectively improve the processing quality of blade surface, is a kind of processing technology can well adapt to the needs of precision machining engine high-performance blade.

Ultra-high speed grinding can achieve ductility domain grinding of hard and brittle materials, and also has good grinding performance of refractory materials such as titanium alloy and nickel-based heat resistant urns. Improving the workpiece surface hardening can reduce the surface roughness value and improve the surface integrity. Therefore, ultra-high speed grinding shows great advance and superiority. It is necessary to strengthen the research and application of ultra-high speed grinding technology, so as to make it play a greater role in the field of blade processing.

---EDITOR: Doris Hu

---POST: Doris Hu