Papers by Author: Guo Sheng Geng

Abstract: Inconel 718 is widely used in aerospace, nuclear power and gas turbine industries. On the other side, it is well known as one of the most difficult-to-cut super alloy and its efficient machining assumes a lot of importance. Therefore, this paper presents an experimental investigation on the cutting force of Inconel 718 machined with several different kinds of cutting tools. Both single-factor and orthogonal experiments were carried out with cemented carbide, cermet and CBN tools. The effects of cutting tools and cutting parameters on the cutting force are investigated and the optimal cutting conditions are recommended.

Abstract: High Speed Machining (HSM) has been proved to be useful in the machining of many materials. This research is concerned with the performance of HSM in the milling of Ti-6.5Al-2Zr-1Mo-1V (TA15) titanium alloy. The tool life and wear mechanism of the milling tool under different cutting speed were investigated, and the influences of cutting speed on the surface integrity and fatigue property of the machined part were studied. According to the experimental results, acceptable tool life can be obtained in a speed range up to 200m/min. The results also show that increasing cutting speed can help to improve the surface integrity and fatigue property of the machined part.

Abstract: Surface integrity has a great effect on the fatigue property of titanium alloy. The surface integrity and fatigue property of a high speed milled Ti-6.5Al-2Zr-1Mo-1V (TA15) titanium alloy were investigated in this research. The main objective of this paper is to study the influence of milling speed on the surface integraty and fatigue property of the machined part. The surface roughness, work hardening, metallurgical structure and residual stress of the machined surface were studied in a cutting speed range of from 50m/min to 300m/min. To verify the relationship between cutting speed and the surface integrity of machined surface, the fatigue property of titanium alloy specimens milled at four different cutting speeds ranging from 50 to 200m/min were compared at two stress levels. This research shows that the cutting speed has little effect on the work hardening, metallurgical structure and residual stress, but the surface roughness decreases with the increasing cutting speed. Therefore, increasing milling speed has a positive effect on the surface integrity and fatigue property of the machined surface.

Abstract: This research is concerned with the influences of cutting speed on the fatigue properties of high speed milled Ti-6.5Al-2Zr-1Mo-1V (TA15) titanium alloy. Four different cutting speeds ranging from 50 to 200m/min were used to mill the specimens for fatigue test, and the fatigue properties of them were studied at two stress levels: 80—800MPa and 90—900MPa. The fatigue lives of the specimens milled under different cutting speeds were compared. The fracture surfaces were analyzed using scanning electron microscope (SEM), and cyclic stress-strain properties of TA15 titanium alloy were investigated with a stress-strain gauge. The results showed that increasing cutting speed can help to improve the fatigue properties of titanium alloy, especially at a relatively low cyclic stress level.

Abstract: Ti-6.5Al-2Zr-1Mo-1V is a near alpha titanium alloy strengthened by solid solution with Al and other components. In this study, a series of experiments on tool wear and surface integrity in high speed milling (HSM) of this alloy were carried out. The tool lives under different cutting speeds were studied and the corresponding empirical equation of tool life was derived. Additionally, the wear mechanism of cutting tools was also discussed. Finally, surface integrity, including surface roughness, metallograph, work hardening and residual stresses, were examined and analysed. The result shows that good surface quality of workpiece could be obtained in HSM of the alloy.

Abstract: Cutting temperature has direct effects on tool wear and tool life, as well as machining accuracy and machining quality. Titanium alloys, however, are generally machined at lower cutting speeds with cemented carbide tools due to its low thermal conductivity and high chemical reactivity with cutting tool materials. This paper deals with cutting temperature in high-speed milling of a near alpha titanium alloy. The measuring principle of cutting temperature by the workpiece-constantan thermocouple method was illustrated and the physical meaning of the electromotive force (EMF) signals was described in the paper. The effects of cutting parameters and wear status on cutting temperature were studied, and the temperature distribution along the cutting edge was investigated.

Abstract: A series of experiments were carried out on normal and high speed milling of a high strength titanium alloy (TA15). TA15 is a close alpha titanium alloy strengthened by solid solution with Al and other component. It is often used to make large structural parts in airplane and welded parts subject to heavy load. The tool life of several typical types of cutter commonly used in the milling of titanium alloy was studied by the orthogonal experiment design method. After multi-element regression analysis, the empirical equation of the tool life was stablished. The milling force and temperature were measured under different cutting conditions and tool wear status. The knowledge is useful to further understand and analysis of the cutting mechanism, machining quality and tool wear. The study on the machined surface integrity includes the following content: surface roughness, metallographic examination, work hardening and residual stress.