An investigation into Vibratory Grinding of hard-to Machine Aerospace Materials
There is an increased demand for high surface finishes and tight tolerances, especially in high value manufacturing processes. However, progress in materials science has led to the development of new materials especially in the aerospace industry, where high heat resistance materials are preferred such as Ti-6Al-4V. These new materials have different mechanical properties from conventional ones. This makes their machinability very unusual when compared to that of conventional materials. Consequently machining these materials poses a significant challenge to industry. Since this alloy has got low density, high strength to weight ratio and also high temperature strength, it is used for aerospace, civil and military aircraft turbine engine compressor blades manufacturing. This research programme sets up an investigation into vibration assisted grinding in a range of frequencies and amplitudes combined with various process parameters in the attempt to grind advanced aerospace materials. Such a novel approach called “Resonance machining” also depends on the Taguchi experimental design method, with the aim of improving the grinding quality and efficiency. The novelty of this new approach is that the vibration assisted resonance was implemented in the axial direction of the grinding feed rate, using an aluminium oxide grinding wheel, with the application of coolant fluid to enhance grinding difficult to machine aerospace materials, this approach is considered to be an alternative to the usage of super abrasive wheels such as CBN and diamond wheels currently been used, with negative effect where damage to the workpiece surface and subsurface crack have been reported. However, the advantages of vibration assisted grinding as a new technique are the reduction of wheel wear and cutting forces. Through over this study it has been proven that vibration assisted grinding allows the wheel to cut in two directions and that will increase the material removal rate reduce the wheel wear, cutting forces and also the power consumption. The purpose of this research is to achieve an optimum performance of vibration assisted grinding processes using difficult-to-machine advanced aerospace materials. The first step in this investigation is to identify the material under investigation. Therefore, the above mentioned aerospace materials have been tested. Initial hardness testing was carried out on two types of materials involved this study, namely Nickel alloy (Inconel 718) and Ti-6Al-4V. This was followed by a chemical element content analysis undertaken on the scanning electron microscope with X-Ray setup. However, this work investigates the grinding performance of titanium and nickel alloys using aluminium oxide (Al2 O3) grinding wheel. Hence, experiments were carried out in wet conditions with/without vibration grinding and the results are provided to confirm the effectiveness of this approach.
TJ Mechanical engineering and machinery, TL Motor vehicles. Aeronautics. Astronautics
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