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1. Physical phenomena in titanium processing. The cutting force required to process titanium alloys is only slightly higher than that for steel of similar hardness, but the physical phenomena involved in processing titanium alloys are much more complex than those in processing steel, which poses significant challenges to the processing of titanium alloys. Most titanium alloys have a very low thermal conductivity, only 1/7 that of steel and 1/16 that of aluminum. Therefore, the heat generated during the cutting of titanium alloys is not quickly transferred to the workpiece or carried away by the chips; instead, it accumulates in the cutting area. The resulting temperature can exceed 1,000°C, causing the cutting edge of the tool to wear down rapidly, crack, and develop burrs. A worn cutting edge in turn generates more heat in the cutting area, further shortening the tool’s lifespan. The high temperatures generated during cutting simultaneously damage the surface integrity of titanium alloy parts, leading to a decrease in their geometric precision as well as work hardening that significantly reduces their fatigue strength. The elasticity of titanium alloys can be beneficial for the performance of components, but during cutting, the elastic deformation of the workpiece is a major cause of vibration. The cutting force causes the “elastic” workpiece to move away from the tool and rebound, resulting in friction between the tool and the workpiece being greater than the cutting force. The friction process also generates heat, exacerbating the problem of poor thermal conductivity in titanium alloys. This problem becomes even more severe when machining easily deformable parts such as thin-walled or ring-shaped parts. It is not easy to machine titanium alloy thin-walled parts to the desired dimensional accuracy. Because as the workpiece material is pushed away by the cutting tool, the local deformation of the thin walls exceeds the elastic range and results in plastic deformation, the strength and hardness of the material at the cutting point increase significantly. At this point, processing at the previously determined cutting speed becomes excessive, further leading to rapid tool wear. ““Heat” is the “culprit” behind the difficulty in machining titanium alloys! 2. Key techniques for machining titanium alloys Based on an understanding of the mechanisms involved in machining titanium alloys, along with past experience, the main techniques for machining titanium alloys are as follows: (1) Use cutting tools with a positive-angle geometry to reduce cutting force, cutting heat, and workpiece deformation. (2) Maintain a constant feed rate to prevent workpiece hardening; the tool must remain in a feeding state throughout the cutting process. During milling, the radial cut depth ae should be 30% of the radius. (3) High-pressure, high-flow cutting fluid is used to ensure thermal stability during the machining process, preventing deformation of the workpiece surface and damage to the tools due to excessive temperatures. (4) Keep the blade edge sharp; a dull knife is a cause of heat accumulation and wear, which can easily lead to tool failure. (5) Process as much as possible in the softest state of the titanium alloy, because the material becomes more difficult to machine after hardening; heat treatment increases the strength of the material and accelerates blade wear. (6) Use a large radius of curvature at the cutting edge or chamfers to allow as much of the blade as possible to be involved in the cutting process. This can reduce the cutting force and heat at each point, preventing localized damage. When milling titanium alloys, among all the cutting parameters, the cutting speed has the greatest impact on tool life vc, followed by the radial feed rate (milling depth) ae. 3. Addressing the challenges in titanium processing by focusing on the cutting tools: The groove wear that occurs in cutting tools during titanium alloy processing is localized wear at the back and front areas along the cutting depth; it is often caused by the hardened layer resulting from previous processing steps. The chemical reactions and diffusion between the cutting tool and the workpiece material at processing temperatures above 800°C are also one of the causes of groove wear. Because during the machining process, titanium molecules from the workpiece accumulate at the front of the cutting tool and are \"welded\" to the blade under high pressure and temperature, forming edge wear. When swarf is peeled off the cutting edge, it takes the cemented carbide coating of the blade with it; therefore, machining titanium alloys requires special blade materials and geometries. 4. Tool geometry suitable for titanium machining. The key factor in machining titanium alloys is heat; a large amount of high-pressure cutting fluid must be sprayed onto the cutting edge in a timely and accurate manner in order to remove heat quickly. The market offers milling cutters with unique structures designed specifically for titanium alloy processing.