Nickel-based superalloys, such as In718 and Waspaloy, are known for their exceptional thermal stability, high-temperature strength, corrosion resistance, and wear resistance. These materials are considered difficult to machine due to their high hardness and tendency to work harden during cutting. They are commonly used in critical components like turbine disks, which are vital parts of aeroengines. Turbine disks operate under extreme conditions, including high stress, temperature, and harsh environments, making them prone to fatigue failure. Therefore, the material selection and manufacturing techniques for turbine disks play a crucial role in the development of high-performance aeroengines. The shaped holes on turbine disks are complex, consisting of multiple arcs and straight lines. Accurate positioning and smooth transitions between segments are essential during machining to ensure the surface roughness meets the required standards. Machining these shaped holes from high-temperature alloys is particularly challenging. Currently, electric discharge machining (EDM) is widely used for this purpose, but it generates heat-affected layers that are difficult to remove using conventional grinding methods. Special processes like abrasive jet machining are often needed, leading to increased processing time and costs. As a result, there is growing interest in developing more efficient and cost-effective methods for machining nickel-based superalloy shaped holes. This paper explores the feasibility of replacing EDM with milling and grinding techniques. Through various combinations of drilling, milling, and grinding, along with the use of coated tools and optimized parameters, the study investigates whether these alternative methods can achieve the desired surface finish and geometric accuracy. The results show that the drilling-milling-grinding process yields the best surface roughness, while the drilling-grinding method produces the roughest surfaces. Milling alone can also produce acceptable results, though grinding improves surface quality at the expense of efficiency and cost. Tool wear and surface roughness were analyzed using a tool microscope and a surface roughness meter. The experiments revealed that milling cutters experience significant wear, especially at higher cutting speeds. Similarly, grinding wheels showed rapid wear and deformation after machining a single hole. These findings highlight the challenges associated with machining nickel-based superalloys, such as work hardening, high thermal stresses, and tool degradation. In addition to surface quality, the study evaluated machining efficiency. Compared to traditional EDM and abrasive jet processes, the milling process significantly reduced the total machining time by 58%. All operations could be performed on a single machining center, reducing auxiliary time and improving overall productivity. Even when an abrasive water jet was used to enhance surface integrity, the total working hours were still much shorter than those required by EDM. In conclusion, the drilling-milling process for machining nickel-based superalloy shaped holes is both feasible and efficient. It meets the geometric and surface finish requirements while offering substantial improvements in processing time and cost. Further optimization of cutting parameters and tool design can further enhance the performance of this method, making it a viable alternative to traditional EDM techniques.

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