The Application of End Mills in the Processing of Aero Engine blades

End mills play a significant role in the processing of aero engine blades. Their applications are reflected in multiple aspects such as processing methods, tool design, and process optimization. The following is an introduction for you:

Processing method

Five-axis linkage processing: Aero engine blades are free-form surface parts with complex geometric shapes, narrow front and rear edges, and structures that are prone to deformation. On five-axis linkage equipment, when using end mills for processing, helical milling is often adopted. That is, in actual processing, a rotary processing method is used where the blade moves from one end to the other in the length direction. This method has a very high processing efficiency and processing accuracy, and can effectively guarantee the processing quality of the blades.

High-speed turning and milling processing: The traditional processing procedures for aviation blades are cumbersome, with numerous clamping operations, low processing efficiency, and significant blade deformation. Moreover, the cross-sectional shape has considerable errors from the original design. The blades are processed by high-speed turning and milling on the five-axis linkage machine. The entire blade can be processed with only one clamping, eliminating the processing errors caused by multiple clamping, reducing the degree of deformation due to processing, and improving the processing quality and efficiency of the blades.

Tool design

Conical ball-end mills: For the integral blisks of aero engines, safe and reliable flexible processing can be achieved through conical ball-end mills. The standard taper ball-end mill is specifically designed as the fastest option for milling parts with a large axial depth of cut. It offers excellent stability and side milling performance.

Ball-end replaceable cutting head tools: For the machining of blades on discs or integral blade discs, the optimal rough machining method is point milling. The use of end mills with ball-end interchangeable cutting heads, such as CoroMill 316 ball-end interchangeable cutting head tools, can ensure the maximum balance between productivity and economy.

Process optimization

Cutting parameter optimization: Scientifically provide cutting parameters such as cutting depth, spindle speed, and feed per tooth based on the effective diameter of the tool. For instance, when using a ball-end milling cutter for processing, if the axial milling depth is less than the tool radius, the effective diameter will be smaller than the nominal diameter of the milling cutter, and the effective speed will also be smaller than the nominal speed. The above situation also occurs when using an arc milling cutter with a shallow cutting depth. Therefore, reasonable adjustments need to be made according to the actual situation.

Tool path planning: Based on the cutting force model, tool axis vector planning is carried out to solve the deformation problem of free-form surface parts such as aero engine blades during the machining process. Comprehensively considering the curvature variation of the workpiece surface and the variation of the vector attitude of the tool axis, an algorithm for calculating the thickness of the undeformed chip in the cutting force model is proposed, thereby extending the existing cutting force model from planar parts to free-form surface parts.

Deal with material properties

Titanium alloy blade processing: Titanium alloys have the characteristics of low specific gravity, high strength, good thermal stability and excellent corrosion resistance, and are increasingly widely used in the manufacturing of aero engine blades. However, titanium alloys have a very low thermal conductivity and strong chemical reactivity. At high temperatures, they are prone to oxidation to form highly hard titanium oxide, which can cause damage to cutting tools. When processing titanium alloy blades, end mills should be used for climb milling as much as possible to reduce blade wear and chipping damage. Small-radius and close-tooth type milling cutters can be adopted. The relief Angle of the milling cutter is generally 30% – 50% larger than that of the standard milling cutter. Taking an appropriate positive rake Angle (5° – 7°) can make the cutting edge sharper and has a significant effect on improving the quality of the machined surface.

Processing of high-temperature alloy materials: Aero engine components such as turbine blades often use high-temperature alloy materials, which are difficult to process. Tools with high hardness, strong wear resistance, excellent cutting performance and stability, such as TOWA-CBN end mills, can be used for processing to meet the requirements of high precision and high reliability in the aerospace industry.