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May 22, 2023
Precautions When Processing Titanium Rod Materials
The thermal conductivity of most Titanium Rod is very low, only 1/7 of steel and 1/16 of aluminum. Therefore, the heat generated in the process of cutting titanium alloy will not be quickly transferred to the workpiece or taken away by the chips, but will be accumulated in the cutting area, and the generated temperature can be as high as 1000 ° C, causing the cutting edge of the tool to wear, crack and die rapidly. Build-up edge build-up, rapid appearance of worn edges, in turn generates more heat in the cutting zone, further shortening tool life. Moreover, the high temperature generated during the cutting process also destroys the surface integrity of titanium alloy parts, resulting in a decrease in the geometric accuracy of the part and a work hardening phenomenon that seriously reduces its fatigue strength.
While the elasticity of titanium alloys can be beneficial for part performance, elastic deformation of the workpiece during cutting is a significant source of vibration. The cutting pressure causes the "elastic" workpiece to leave the tool and rebound, so that the friction between the tool and the workpiece is greater than the cutting action. The friction process will also generate heat, which will more easily lead to the problem of poor thermal conductivity of titanium alloys.
Especially when processing thin-walled or ring-shaped parts that are easily deformed, this problem is even more serious. Because as the workpiece material is pushed away by the tool, the local deformation of the thin wall has exceeded the elastic range to produce plastic deformation, and the material strength and hardness at the cutting point increase significantly. At this time, the machining at the originally determined cutting speed becomes too high, which further leads to sharp wear of the tool. However, after mastering the processing know-how, the wear of cutting tools can be reduced to some extent to improve the cutting quality of titanium alloy workpieces. Mainly as follows:
1. Adopt blade with positive Angle geometry shape to reduce cutting force, cutting heat and workpiece deformation
2. Maintain a constant feed to avoid hardening of the workpiece, the cutting tool should always be in the feed state in the cutting process, milling radial cutting amount a e should be 30% of the radius.
3. High pressure and large flow cutting fluid is adopted to ensure the thermal stability of the processing process and prevent the workpiece surface degeneration and tool damage due to high temperature.
4. Keep the cutting edge of the blade sharp, blunt tools are the cause of heat buildup and wear, easy to lead to tool failure.
5. Machining titanium alloys in the softest state possible, as the material becomes more difficult to work after hardening, and heat treatment increases the strength of the material and increases blade wear.
6. Use large tip radius or chamfering to cut in as much of the blade as possible. This reduces cutting force and heat at every point, preventing local breakage.