Application Case of 5-Axis Machining in Aero-Engine Turbine Blade Manufacturing-News

As the core power component, aero-engine turbine blades are responsible for the key task of converting high-temperature gas energy. Their machining accuracy directly determines the engine's thrust, fuel efficiency and operational stability. This component generally adopts GH4169 superalloy, which has high strength, corrosion resistance and creep resistance, but is extremely difficult to machine. Moreover, the blade features a variable-section twisted curved surface structure, including complex characteristics such as narrow channels, tenon grooves and film cooling holes, imposing harsh requirements on manufacturing technology. Taking the mass machining project of turbine blades of an aviation manufacturing enterprise as an example, this paper expounds how 5-axis machining technology breaks through the bottleneck of traditional processes and achieves the unification of high precision and high efficiency.

I. Project Background and Core Machining Difficulties

The cooperative customer of this project is a leading domestic enterprise engaged in aero-engine R&D and production, which needs to machine high-pressure turbine blades for large bypass ratio turbofan engines with an annual demand of 12,000 pieces. The overall size of the blade is 180mm×65mm×22mm, and the minimum thickness of the blade tip is only 0.8mm, making it a typical thin-walled complex component. Combined with material characteristics and design requirements, the core machining difficulties are concentrated in three aspects.

First, the material has extremely poor machinability. GH4169 superalloy maintains good strength at high temperatures, with large cutting resistance and low thermal conductivity during cutting—only 1/5 of that of 45# steel. Cutting heat is easily concentrated at the tool tip, leading to severe tool wear and thermal deformation of the workpiece. Second, it is difficult to control the precision of complex structures. The blade profile is a complex twisted curved surface, with a profile tolerance required to be ≤±0.03mm. The spacing of narrow channels formed by adjacent blades is only 5mm, and traditional 3-axis machining is prone to tool interference and machining blind spots; the coaxiality error between the tenon groove and the blade body must be controlled within 8μm, and multi-process clamping is likely to accumulate errors. Third, thin-walled deformation and high surface quality requirements. The thin-walled area of the blade is prone to extrusion deformation by cutting force during machining, and the surface roughness needs to reach Ra≤0.8μm to avoid stress concentration under high-temperature gas scouring.

II. Overall 5-Axis Machining Solution

In response to the above difficulties, the technical team adopted a solution of "customized equipment + refined process + closed-loop inspection", taking the Starrag LX 051 5-axis simultaneous machining center as the core, combined with special tooling, tools and intelligent inspection systems, to build a full-process machining link.

(I) Equipment and Tooling Configuration

A cradle-type 5-axis machining center is selected, equipped with the Siemens 840D sl CNC system. The positioning accuracy of the X/Y/Z linear axes reaches ±0.002mm, and the indexing accuracy of the A/C rotating axes is ≤10″. It has high-speed linkage and dynamic accuracy compensation functions, which can accurately adapt to the machining of complex blade curved surfaces. The tooling adopts an adaptive hydraulic support fixture, which adjusts the support points based on the actual contour of the blade blank, applies 50-100N dynamic support force to weak areas such as the blade tip and edge, and avoids clamping stress and cutting deformation; through tenon groove positioning, one-time clamping is realized to complete the integrated machining of the blade profile, tenon groove and film cooling holes, eliminating multi-clamping errors.

(II) Tool and Cutting Parameter Optimization

Sandvik AlCrN-coated cemented carbide tools are selected. R5 ball-end tools are used for blade profile machining, customized forming tools for tenon groove machining, and solid carbide drills for film cooling hole machining. The tool hardness reaches above HRC65, which can withstand high-temperature cutting wear. The cutting parameters are optimized through multiple rounds of trial cutting: in the rough machining stage, the speed is 3500r/min, the feed rate is 0.12mm/r, the depth of cut is 0.5mm, and spiral layered cutting is adopted to quickly remove the allowance; in the finish machining stage, the speed is increased to 8000r/min, the feed rate is 0.08mm/r, the depth of cut is 0.1mm, combined with Minimum Quantity Lubrication (MQL) technology, vegetable oil-based lubricating fluid is sprayed in mist form to the cutting area to reduce cutting heat and tool wear.

(III) Linked Machining Process Design

A three-stage process of "rough machining - semi-finish machining - finish machining" is adopted. The 5-axis simultaneous machining path is generated by UG CAM software, and a residual height calculation model is introduced to control the residual height of the blade surface within 5μm. After rough machining, cryogenic treatment (-80℃ for 2 hours) is performed to release machining stress; semi-finish machining adopts contour line cutting path to correct the rough machining contour error; in the finish machining stage, the workpiece attitude is adjusted in real time through the A/C axes to keep the tool consistent with the blade normal vector at all times, avoiding local overload of the cutting edge, and completing the inclined machining of film cooling holes to ensure hole position accuracy. The whole process realizes interference-free continuous cutting, and the single machining cycle is shortened by 40% compared with traditional processes.

(IV) Full-Process Closed-Loop Inspection

A "on-line monitoring + finished product full inspection" system is built: during machining, the Renishaw probe system scans the blade size in real time, dynamically feeds back deviation data, and the CNC system automatically compensates for tool wear and machine tool errors; coordinate measuring machine is used for finished product inspection to detect more than 50 key features, combined with laser scanning to verify profile accuracy, and 3% of samples are randomly selected from each batch for high-temperature strength testing to ensure stable product qualification rate.

III. Application Effects and Industry Value

After four consecutive months of mass production verification, the solution has achieved dual breakthroughs in machining quality and efficiency. In terms of precision, the blade profile error is stably controlled within ±0.02mm, the coaxiality and surface roughness all meet aviation standards, and the scrap rate is reduced from 40% of traditional processes to 3.2%. In terms of efficiency, the single-piece machining cycle is shortened from 2.5 hours to 1.4 hours, the single-shift production capacity is increased by 62%, and the annual production capacity reaches 15,000 pieces, exceeding customer demand. In terms of cost, the service life of tools is extended by 30%, labor input is reduced by 70%, and the comprehensive manufacturing cost is reduced by 38%. At the same time, the support structure removal process of traditional processes is avoided, and the material utilization rate is increased by 15%.

This case fully demonstrates the core enabling value of 5-axis machining technology in the manufacturing of complex aviation components. Through the in-depth integration of multi-axis linkage, adaptive machining and closed-loop inspection, it breaks through the machining bottleneck of superalloy thin-walled components. In fields such as aerospace and high-end equipment, such solutions can be widely applied to the manufacturing of complex parts such as impellers and guide vanes, providing a reference for the industry's transformation towards high precision, high efficiency and greenization. In the future, with the upgrading of digital twin and adaptive machining technology, 5-axis machining will further realize the coordination of personalized customization and large-scale production, promoting the iteration and upgrading of the high-end manufacturing industry.