Why do we think titanium alloy is a difficult-to-process material? Because we lack a deep understanding of the processing mechanism and phenomenon of titanium alloys.
The cutting force of titanium alloy processing is only slightly higher than that of steel of the same hardness, but the physical phenomenon of processing titanium alloy is much more complicated than processing steel, which makes titanium alloy processing face huge difficulties.
The thermal conductivity of most titanium alloys is very poor, only 1/7 that of steel and 1/16 that 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 concentrated in the cutting area. The temperature generated can be as high as 1,000 ℃, causing the cutting edge of the tool to wear, crack and quickly Generate built-up edge, wear blades quickly appear, and generate more heat in the cutting area, further shortening the life of the tool.
The high temperature generated during the cutting process also destroys the surface integrity of the titanium alloy parts, resulting in a decrease in the geometric accuracy of the parts and a work hardening phenomenon that severely reduces its fatigue strength.
The elasticity of titanium alloy may be beneficial to the performance of parts, but in the cutting process, the elastic deformation of the workpiece is an important cause 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 also generates heat, which aggravates the poor thermal conductivity of titanium alloys.
This problem is even more serious when processing thin-walled or ring-shaped parts that are easily deformed. It is not an easy task to process thin-walled titanium alloy parts to the expected dimensional accuracy. Because when the workpiece material is pushed away by the tool, the local deformation of the thin wall has exceeded the elastic range and plastic deformation occurs, and the material strength and hardness of the cutting point increase significantly. At this time, machining according to the originally determined cutting speed becomes too high, which further leads to sharp tool wear.
In summary, heat is the main reason for titanium alloys becoming difficult to process materials.
The machinability of titanium alloys is poor compared to both general steel and stainless steel, which places special demands on the CNC cutting tools. However, UKO has a grade of milling insert, EG9335-J66, for the processing of titanium alloys, the effect is obvious, and the feedback from customers is also very good. If any demands on milling inserts for titanium alloy, just contact us.
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