Fundamental Research On High Speed Milling Of Titanium Alloys

Titanium alloys find more and more applications in many industrial fields because of their high specific strength, good corrosion resistance and high thermal stability. However, titanium alloy is well known as a difficult to machine material, because of its low thermal conductivity, small elastic module, and high chemical activity. Many researchers have put their attentions on the high speed machining (HSM) of titanium alloy. In this paper, some researches were carried out on the fundamental aspects of high speed milling of titanium alloys, such as the cutting force, cutting temperature, tool wear, surface integrity and the influence of cutting speed on the fatigue property of the finished product.1. Cutting force in high speed milling of titanium alloyThe relations between cutting force and milling parameters, tool wear, and different workpiece materials were investigated respectively. The variation of the cutting force in tool coordinate system and the frequency properties of the cutting force were studied. The effects of high frequency components and impact on the cutting force were also analyzed.2. Cutting temperature in high speed milling of Ti alloyCutting temperature was measured by a constantan-workpiece thermal couple. The physical meaning of the acquired electromotive force (EMF) signals was analyzed. Based on this analysis, the temperature variation and the thermal impact of the cutting edge during a cutting cycle were investigated. The effects of cutting speed, tool wear, and other cutting conditions on the milling temperature were also investigated.3. Tool life and tool wear mechanismOrthogonal and single factor experiments were carried out to investigate the relations between tool life and cutting parameters. The effects of tool and workpiece material on tool life were also studied, and the empirical equations of tool life were established. Tool wear mechanism and characteristic in high speed milling of titanium alloy were analyzed by scanning electron microscope (SEM) and energy disperse spectroscopy (EDS).4. Surface integrity in high speed milling of titanium alloyThe surface roughness, metallograph, work hardening, and residual stress in high speed milling of titanium alloy were examined. The effects of milling parameters and tool wear status on the surface integrity were investigated. The results show that HSM has no negative effect on the surface integrity.5. Effect of cutting speed on the fatigue property of the finished productsComparative experiments were adopted to study the effects of cutting speed on the fatigue property of the finished products, and the fracture surfaces were analyzed by SEM. The result shows that improving cutting speed in a certain range contributes to improve the fatigue property of the finished products.