Titanium alloy machining brings great challenges to cutting tools

Titanium has a variety of properties that make it a very attractive component material, but many of these properties also affect its machinability. The titanium alloy commonly used in industry is two-phase titanium alloy, namely (α+β) titanium alloy. TC4 and TC6 are commonly used in aviation engine fuel accessories, among which TC4 is a typical representative of this kind of alloy. Titanium alloy material has high hardness, poor cutting performance, and easy to produce work hardening phenomenon, which brings difficulties to cutting. For TC4 parts in titanium alloy, especially the turning process, AVIC West control has done more in-depth research and gained some experience.

First of all, the elastic modulus of titanium alloy is small, the elastic modulus of TC4 E=110GPa, about half of steel, and low thermal conductivity, so the elastic deformation of the workpiece caused by cutting force is large, and at the same time, high and concentrated cutting force will be generated in the process of machining. It is easy to produce vibration and lead to vibration when cutting, reduce the accuracy of the workpiece, so to improve the rigidity of the machining system.

Secondly, titanium alloy in the cutting process of local high temperature, so that titanium is easy to absorb atmospheric oxygen and nitrogen, so as to form a hard and brittle skin. This will cause the work hardening of the workpiece surface, and the work hardening speed is fast, making the surface of the tool to produce serious scratches, easy to produce the phenomenon of chipping edge in the cutting process.

In addition, the physical and chemical properties of titanium alloy material itself make its cutting with the workpiece affinity, cutting tool and workpiece contact easy to produce sticky knife phenomenon, increase the friction between the tool and the workpiece, produce a lot of cutting heat. The resulting large amount of cutting heat cannot be dissipated through the chip in time, greatly reducing the tool life. Therefore, the tool for processing titanium alloy must have high thermal hardness.