Aeroengine components are increasingly made from advanced high-strength, high-temperature alloys, powder metallurgy steels, single-crystal alloys, and lightweight composite materials. These materials significantly increase the complexity of the cutting process and demand more sophisticated machining technologies. When dealing with difficult-to-machine materials, conducting cutting tests is essential to determine the most suitable tool materials and coatings that can adapt to both the workpiece material and the specific cutting conditions.
In the Engineering Technology Room, Engineer Xu Min has been working on optimizing machining processes for challenging materials. One key area of focus is the selection of tools for machining nickel-based superalloys, which are commonly used in high-temperature aerospace engine components operating below 650°C. However, these alloys present challenges such as hard spots, poor thermal conductivity, and significant work hardening, making them difficult to machine. Our company primarily works with GH2132, a nickel-based superalloy with a hardness of 320 HBW, and parts with a length of φ10 × 2000 mm. The required surface roughness is Ra = 1.6 μm, and the aspect ratio is as high as 18, making it a typical slender shaft part.
To address these challenges, we use a CNC vertical slitting automatic lathe model CKN1120IV from Sichuan Pushinjiang Machine Tool Co., Ltd. Based on cutting tests and analysis, we have selected hard-coated inserts, specifically MT09T304-PM5-WSM30, for machining nickel-based superalloys. For GH2132, the main rake angle is typically between 40° and 50°, while the secondary rake angle ranges from 0.5° to 3°. The back rake angle is set between -10° and -20°, which helps prevent built-up edge and ensures good surface quality. The optimal cutting speed is between 95–120 m/min, with a feed rate of 0.1–0.15 mm/rev, ensuring the desired surface finish.
Another challenging material we work with is powder metallurgical tool steel (AHP10V), known for its uniform microstructure, fine grains, and high yield strength. However, its high content of alloy elements like chromium, cobalt, and molybdenum makes it extremely difficult to machine. The material's unique properties cause an increase in hardness at certain temperatures, and its porous structure leads to localized hardness fluctuations, with some particles reaching up to 60 HRC. This results in severe edge wear during cutting.
Through testing, we selected S05F material with a carbide blade 4205F, designed for cutting wear-resistant alloys. It features a fine grain structure and a thin 4μm CVD TiCN-Al₂O₃-TiN coating, making it ideal for finishing operations on powder metallurgical tool steel. The recommended cutting parameters are v=30–60 m/min, ap=0.25 mm, f=0.1 mm/r. Initially, the surface quality was poor, with chipping observed on the tool. Upon inspection, it was found that the blade was not properly secured, causing vibration during cutting. After adjusting the installation, the cutting parameters were optimized to v=35 m/min, ap=0.25 mm, f=0.1 mm/r. The results improved significantly, with smooth cutting, manageable chip formation, and a surface runout of approximately 0.01 mm.
After processing 5 pieces, the tool showed signs of wear, and after 10 pieces, the flank face exhibited groove wear, along with edge and boundary damage. Due to the material’s poor thermal conductivity, there was a tendency for built-up edge and adhesion, making the cutting process similar to grinding. Additionally, the presence of hard spots in the material caused impact damage to the tool, contributing to the observed wear patterns.
The development of modern cutting technology relies on the integration of advanced tool structures and innovative cutting techniques. By carefully selecting blade geometry, optimizing cutting parameters, monitoring cutting forces and chip formation, and making timely adjustments, we ensure smooth and efficient machining. Continuous innovation in this field not only improves production efficiency but also meets the strict precision requirements of design drawings and process specifications, ultimately enhancing the competitiveness of our enterprise.
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Shandong Yahong New Materials Technology Co., Ltd , https://www.okrooftile.com