Analyzing High-Temperature Alloys： Properties, Machining Challenges, and Solutions)

Welcome back to Yijin Hardware. High-temperature alloys present a significant challenge in the machining industry. With advancements in material technology, the market share of high-temperature alloys is steadily increasing. It has become crucial to find more efficient and cost-effective ways to machine these materials. In this session, we will explore the material properties and machining difficulties of high-temperature alloys in just a few minutes to see if we can find solutions to these problems. Subscribe now to get started. High-temperature alloys can be broadly classified into three categories based on their matrix. Iron-based, nickel-based, and cobalt-based alloys. As the name suggests, high-temperature alloys offer greater heat resistance compared to alloy steels. They exhibit reliable stability, high strength, low thermal expansion, and good thermal conductivity in high-temperature environments. They are primarily used in various components of gas turbines and aircraft engines, such as casings, blades, and turbine discs. These alloys are costly, and their market share is increasing year by year. Due to their low thermal conductivity, which is typically only 20 to 40 percent that of steel, high-temperature alloys led to elevated cutting-edge temperatures during machining. Additionally, their high chemical reactivity can result in chemical reactions with tool coatings at elevated temperatures, causing rapid degradation of the coating and failing to protect the tool effectively. The cutting resistance of high-temperature alloys is 50 percent higher than that of medium-carbon steels, necessitating better overall tool strength. After machining, the surface often experiences significant hardening and residual stress, with hardness levels reaching 200 percent to 500 percent. This leads to faster wear of the cutting edge during subsequent machining, greatly shortening tool life. These factors often result in phenomena like tool burning, sticking, and breakage when machining high-temperature alloys, reducing tool durability, and causing instability during machining. Therefore, strictly controlling cutting temperatures and avoiding chemical reactions with high-temperature alloys is the most effective solution. Let's dive into the details of the machining process. One, under medium to small excess stock conditions, it's advisable to use solid carbide tools with side cutting edges, keeping the cutting speed within 30 to 50 meters per min. Slower machining speeds help lower cutting temperatures. Utilizing the larger heat dissipation area of the tool's side edge can effectively address overheating issues in the area. The coolant should be directed fully onto the cutting edge, and using tools with internal cooling is the optimal choice. High-temperature alloys should be machined with specialized milling cutters coated with inert metals to resist chemical reactions and protect the tool, extending its lifespan. For improved machining efficiency, ceramic-based milling tools can be used with dynamic machining techniques for roughing. Ceramic tools have high red hardness and can withstand higher machining temperatures, achieving cutting speeds of 400 to 600 mm, about 10 times that of solid carbide tools. However, they are hard and brittle, so they cannot handle large cutting widths. Typical machining parameters involve a depth of cut of 3 to 5% of the tool diameter. Two, under suitable conditions with high torque on the machine tool spindle, using a corn milling cutter with dynamic milling techniques can achieve a large depth of cut with a small width, similar to solid carbide milling tools, leveraging the tool's side edge's heat dissipation advantage to improve tool life. Three, when finishing curved surfaces, opt for ultra-precision tools instead of ball-end mills. Uh, the large arc profile of the tool allows for effective side cutting, enhancing tool life and efficiency. Four, for deep cavity machining, the machine should ideally be equipped with high-pressure coolant through the spindle, combined with internal cooling tools to promptly reduce the temperature of both the product and the tool, preventing deformation and wear from excessive heat. High-pressure coolant can also remove chips promptly to avoid accumulation that could cause tool breakage. During roughing, using an insert milling method can effectively reduce radial cutting forces as the tool engages the workpiece quickly with minimal movement, reducing cutting heat. This approach not only extends tool life but also minimizes workpiece deformation, offering greater machining stability and metal removal rates compared to side milling. That wraps up this session. We invite you to subscribe to our channel for more technical insights. Let's progress together and enhance our skills, our skills. See you next time.