Key Engineering Materials Vols. 291-292

Abstract: The stable industrial trends towards improvement of product accuracy and quality call for necessity to widen the nomenclature of details surfaces and materials, which need finishing. The method of magnetic abrasive finishing (MAF) helps to meet these challenges. This paper presents the results of study of technological potential of MAF equipment with rotating working area, filled with magnetic-abrasive powder. Such equipment allows to polish the cylindrical, conical and helical surfaces of core details made of magnetic and non-magnetic materials. Geometrical accuracy and roughness of the above mentioned surfaces after MAF and also the conditions of their performance theoretically and experimentally studied. It is established that MAF changes the fine structure of detail surface layer made of hardened high-speed steels, titanium and aluminum alloys and improves their surface performance.

Abstract: The results of the research of the interaction of the abrasive granule with processed surface at vibroabrasive processing are presented. The mechanism of the micro cutting process is described on the base of the analysis of the nature of single traces of the processing, dynamic parameters of the process, geometric parameters of abrasive grains and granules.

Abstract: The examination of deburring and surface finishing (DSF) quality was held at the enterprises of Russia. Here are the results of the examination. It was held on the base of general conclusion from the Scientific Research Institute “V and T” investigation results. The practical use of DSF at the engineering plants was also taken into account.

Abstract: The purpose of the research is the development of theoretical foundation of processing of details by free abrasives, the increase of efficiency of finishing processing of details on the base of creation of methodical principles of optimization of technological processes by means of CAD.

Abstract: In resent years, ceramic balls have been applied into precision bearings and other parts far and wide because of its advantages in light weight, high hardness, abrasive resistance, high-temperature resistance, corrosion resistance, little heat expansion coefficient and so on. The high-precision ceramic balls are machined by lapping usually, and the method of lapping has an important influence on the machining precision and efficiency of ceramic balls. In order to improve the precision and efficiency of ceramic ball machining, in the paper, a new cone lapping method is researched by the lapping experiment. The research result shows that the cone method is the optimal lapping method with high precision, high efficiency and the very simple machine. Furthermore, the mechanics characteristic of the cone lapping method have been analyzed and summarized, which will provide the basic principle and theoretical basis for the choice of primary geometry and mechanics parameter in the process of ceramic balls lapping.

Abstract: In order to avoid the stochastic damage of micro cleavage on cutting edge, a brittle-ductile transition lapping mechanism is proposed for the mechanical lapping of single crystal diamond cutting tools to direct the tools lapping. As expected, the critical depths of cut for brittle-ductile transition in different orientations and on different crystal planes are calculated. According to the theoretical results, the actual dynamic depth of cut is controlled within the critical depth of cut, which ensures that the tool lapping is carried out in ductile regime and the changes of cutting edge radius characterize with some specific time laws in lapping. Therefore, the time series and nonlinear least square methods are used to analyze the changing laws of cutting edge radius. As a result, a coupled model to build a bridge between the cutting edge radius changes and lapping time is developed. In terms of this developed model, a required cutting edge radius restricts a tool’s lapping time. Above all, the cutting edge radius is known in advance and has no needs measuring. So the production efficiency of diamond cutting tools is improved and its production cost is reduced accordingly.

Abstract: This paper describes an experimental investigation of the effects of the particle blend ratio on surface quality in surface polishing using magnetic polishing liquid (MPL). MPL is produced by mixing sub-micrometer- or micrometer-size abrasive particles into a Magnetic Compound Fluid (MCF), a functional fluid composed of MF(Magnetic Fluid) and MRF (Magneto-rheological Fluid), that reacts with magnetic fields. As a step toward establishing the new surface finishing technology using MPL, it is essential to clarify the effects of the blend ratio of particles to solvent in MPL. For this purpose, first five kinds of kerosene-based MPLs with different blend ratios of particles were prepared, then polishing operations involving stainless steel workpieces were carried out on an experimental rig developed in-house. During the experiments, steady state magnetic fields with different strengths were applied while the contact force between the workpiece and the polishing pad was kept constant. The experimental results showed that the blend ratio of particles affects the work-surface quality significantly. Following SEM and optical microscopy observations of the polished work-surfaces, an appropriate blend ratio, under which the surface roughness improved from the original value of Ra100nm to a final one of Ra24nm after polishing for 30min, was recommended.

Abstract: When a light-excitation substance such as a high polymer absorbs the light energy of an ultraviolet ray, it will be excited. If this substance reacts with the processing material in an atomic order under the excited conditions, it may be available for use in fine processing. Thus, it appears that the processing in a sub-nanometer order may be realized by a phenomenon called luminescence. The following merits can be considered: 1) little reaction heat, 2) little heat influence on the processed material, 3) easy reaction control in comparison with chemical processing. In this research, the processing principle was verified by dipping the processing material for a fixed time in pure water mixed the fluorescent substance exposed to an ultraviolet ray. The surface of copper that had been precisely lapped was used in the experiment. The abrasion of its surface was observed by AFM. Based on the results of these basic experiments, an ultraviolet-ray irradiation type polisher was manufactured for use in the polishing experiment of copper. This paper describes the polishing characteristics of copper exposed to an ultraviolet ray.

Abstract: Micro axis-symmetric aspherical glass lenses are being increasingly used in digital devices and optical devices. The glass lenses are molded by using micro ceramic dies such as tungsten carbide [1].Recently, as the pixel number of digital image sensors increases, the accuracy of micro molding dies are required to be much more precise than ever [2]. In this study, ultrasonic assisted polishing method is proposed and developed in order to finish micro axis-symmetric aspherical dies which were pre-ground with a diamond wheel [3]. In this paper, the proposed polishing method was applied to the micro aspherical molding dies to finish form compensation processing.

Abstract: The miniaturization of semiconductor devices is advancing rapidly. The requirement for wafer flatness is becoming increasingly stringent as the use of shorter wavelengths in the latest laser lithography results in a smaller focusing depth of field. In our research, a flatness of 0.1 µm has been achieved over an entire 12" wafer surface by planarization with oscillation speed control type polishing. However, in addition it is necessary to increase the removal rate in order to reduce the polishing time. Although high rotational speed polishing is a solution to meet this requirement, the polishing characteristics change with the rotational conditions. Using a simulation program, we calculated that the stock removal saturates as the rotational speeds of the wafer and polishing pad are increased beyond a certain point. Also, experimental results showed that at high rotational speeds actual stock removal is significantly less than that indicated by the simulation, and that too much slurry causes unnecessary etching.