Papers by Keyword: Precision Machining

Abstract: SiC material removal mechanism and ELID grinding mechanism is analyzed, the character and condition of brittle to ductile transition of SiC single crystal, the critical depth of cut, and surface formation mechanism of ductile mode grinding of SiC single crystal are studied, the experiment results show that ELID grinding can realize ductile grinding ,this will lower the surface damage and improve the machining efficiency.

Abstract: Different inertia effect causes different control errors. To have an optimal control performance, the control parameters of a CNC machine tool should be adaptively tuned based on the variation of the weight of the workpiece in machining process. In this study, simulation based on a theoretical model was made to investigate the influence of inertial effect and friction force on the servo accuracy of a CNC machine tool’s. By using empirical method, an adaptive tuning system that can auto-tune the CNC control parameters based on the detected weight of workpiece was developed. An on-machine weight identification system that can on-machine identify the weight of the workpiece was developed. After integrating the two systems, a control parameter tuning system which can be implanted into CNC controller was developed with the macro executor. Experimental results have shown that the system can effectively improve the accuracy of a machine tool through adaptively tuning control parameters based on the current weight of the machined.

Abstract: Precision hard machining is a topic of high interest at present. Surface integrity requirements increase. Precision machining may substitute some abrasive operations with some advantages of precision machining over the abrasive machining. But, the availability of hard machining over abrasive machining can also lead to economic advantages. Manufacturing processes, machine tools, cutting tools, tool changes, cutting conditions, etc., are nowadays usually determined intuitively, very often non-professionally, without careful analysis and economic calculation. The determination of cutting conditions is very important aspect of the total optimisation of manufacturing processes. Hard machining is possible to realise by different cutting materials, especially by cubic boron nitride, ceramics and some types of sintered carbides.

Abstract: The precision turning experiments of aluminium composites reinforced with SiC whisker reinforcements were done by polycrystalloid diamond (PCD) tools. The measure analysis of the machined surface was carried out with Atom Force Microscope (AFM) and Scan Electronic Microscope (SEM). The roughness values of the machined surface were measured by Talysurf-6. The results show that the orientation of reinforcements in the machined surface will directly affect the deformation mechanism of SiC whiskers, microstructures of the machined surface, and to determine the quality of the machined surface. In the five types from A to E of SiC whisker orientation, the orientation of case A easily makes to produce SiC whisker deformation by cutting off directly, and to result in the best machined surface. However, for the orientation of case E, it easily makes to induce SiC whisker deformation by pulling out or pressing into aluminium matrix, and to produce the worst machined surface.

Abstract: Ultra-precision machining is used for many engineering applications where the traditional processes fail to work. Focused ion beam (FIB) technology is a very important part of the ultra-precision machining. It can realize the precise positioning, microscopic observation and micro machining. This paper introduces the FIB system and its application. FIB system contains ion source, focusing and scanning equipment and sample station. FIB technique has many unique and important functions. It is widely used in semiconductor device fabrication and circuit failure analysis. It can realize sample etching, imaging, thin film deposited, ion implantation and micromachining.

Abstract: Fast tool servo is increasing applied to manufacture optical freeform surfaces, which are adopted in aerospace, imaging, bioengineering, energy fields to improve the performance of the system, simplify the structure of the system and lower cost. The existing FTS have limited stroke and bandwidth. FTS driven by electromagnetic force is discussed. The analysis of the magnetic circuit, the requirements of the system and the corresponding design parameters are studied. The designed FTS can realize the bandwidth of 0-100kHz with a special designed driver.

Abstract: Monocrystalline silicon is typical of hard brittle materials, a high surface quality can be obtained in ductile-regime cutting. The success of the turning process depends on optimizing the machining parameters such as the tool edge radius, tool rake angles, depth of cut and cutting speed, etc. In this study, based on the ductile–brittle transition mechanism, the optimization of cutting parameters were determined with the commercial, general purpose FEA software Msc.Marc. The result demonstrates that the value of temperature is minimum when the tool rake angle is in the range of -15º～-30º. Smaller tool edge radius was selected while maintaining quality of tool edge radius and tool life. As long as beyond the range of cutting speed 6 ~ 8 mm/s, smaller residual stress can be obtain.

Abstract: This paper analyzes the factors affecting the machining accuracy. Specific analysis of the causes of error, and take appropriate precautions to reduce processing errors, improve the machining accuracy.

Abstract: The quality of a machined surface is becoming more and more important to satisfy the increasing demands of sophisticated component performance, longevity, and reliability. The objective of this paper is to analyze the performance of precision turning using conventional lathe on Ti6Al4V under dry working conditions. Various parameters that affect the machining processes were identified and a consensus was reached regarding its values. The proposed work is to perform machining under the selected levels of conditions and parameters and to estimate the, cutting temperature and surface roughness generated as the result of the machining process. ANOVA is used to find the percentage contribution of each parameter to the surface roughness and cutting temperature.

Abstract: The Ti-6Al-4V titanium alloy is commonly used in aerospace, automotive industries and for manufacturing of medical implants, due to its biocompatibility. The objective of this work is to investigate the performance of precision turning using conventional lathe on Ti6Al4V under dry working conditions. A range of parameters that involve the machining processes were recognized and a consensus was reached to finalize its values. The proposed work is to carry out machining under the selected levels of parameters to evaluate the cutting force and surface roughness generated as the consequence of the machining process. Cutting speed, feed rate, depth of cut and nose radiuses are considered as the machining parameters for experimentation. The variation in the surface roughness and the cutting force for the variation of each machining parameters are presented graphically.