How to optimize the cutting parameters in titanium alloy processing?

Titanium alloys (such as TC4 and Ti-6Al-4V) have a low thermal conductivity (only 1/5 of that of steel), high high-temperature strength, and strong chemical reactivity (easily bonding with cutting tool materials). During the cutting process, they are prone to "high-temperature adhesion wear" and "vibration", and specific parameter optimization is required for targeted solutions:

1. Cutting speed (Vc)
Hard alloy cutting tools (such as WC-Co based, with TiAlN coating recommended): Rough machining at 50-100 m/min, finish machining at 80-150 m/min;
Ceramic cutting tools (such as Al₂O₃-TiC) or CBN tools: can be accelerated to 150-300 m/min (suitable for high-speed precision machining);
Avoid low speed (< 30 m/min): It is prone to cause the tool to break due to excessive cutting force.
Core limitation: When cutting titanium alloy at high speed, the temperature in the cutting zone surges sharply (reaching 800-1000℃), which can cause the tool (such as high-speed steel) to rapidly soften. At the same time, titanium alloy is prone to undergo chemical reactions with the tool material (such as tungsten, cobalt), forming a low-strength bonding layer, which accelerates the failure of the tool.

2. Feed rate (f)
Core contradiction: If the feed rate is too high, it will increase the cutting force (since titanium alloys have high plasticity and large deformation resistance), resulting in workpiece deformation or vibration; if it is too low, the friction between the cutting edge and the workpiece surface will intensify, causing a "ploughing effect" and increasing the surface roughness.
Optimization range: Rough machining 0.15 - 0.3 mm/r, Finish machining 0.05 - 0.15 mm/r (The feed rate needs to be matched with the cutting speed. At high speeds, a smaller feed rate should be selected to control the temperature.)

3. Cutting depth (ap)
Principle: Prioritize ensuring sufficient cutting depth to avoid the hardened layer on the workpiece surface (after titanium alloy processing, a cold work hardening layer is likely to form on the surface, with hardness increasing by 20%-50%), and reduce the friction and wear between the tool and the hardened layer.
Optimization range: Rough machining 2-5 mm, finish machining 0.5-2 mm (this needs to be combined with the rigidity of the machine tool to avoid chatter).

4. Auxiliary Optimization
Tool geometry parameters: A larger rake angle (10° - 15°) is adopted to reduce cutting force, and a smaller clearance angle (5° - 8°) is used to enhance the strength of the cutting edge.
Cooling lubrication: High-pressure cooling (pressure 5-20 MPa) + extreme pressure cutting fluid (containing sulfur and phosphorus additives), enhancing heat dissipation and inhibiting adhesion.