Advanced Materials Research Vols. 76-78

Abstract: Magnetic compound fluid (MCF), a functional fluid responding to magnetic field, is expected for an application to many engineering fields. In this paper, the effect of magnetic fields on the polishing force and the restoring ability of the MCF are studied followed by the proposal of a new polishing technique using the MCF. Under a fluctuating magnetic field generated by a revolution of permanent magnet, the magnetic particles in the MCF show a higher particle disposition and an accumulating action compared to a static magnetic field. Thus the MCF generates the greater restoring ability but the lower polishing force compared to that under the static magnetic field. When the MCF under the fluctuating magnetic field is applied to the polishing as the flexible tool, it shows the high polishing performance. As a result, a feasibility of a new polishing technique using the MCF for a three-dimensional structure is confirmed.

Abstract: The distribution of magnetic field in the container is important for the polishing ability of a permanent magnet-type magnetic barrel finishing machine. Therefore, in this study, the magnetic field distribution was measured with different magnets arrangement. It is found that the polarity and strength of magnets on a magnet block greatly affect the distribution of magnetic field. Polishing experiments were done to investigate the polishing ability. The relationship between the magnetic field distribution and the polishing ability was discussed. As a result, it was concluded that strong magnetic field led to superior polishing ability.

Abstract: For the improvement of the performance in centrifugal disc finishing, the flow-through system for supplying the compound solution is tried and its influences on finishing characteristics are experimentally investigated. Workpieces (22 mm in diameter and 15 mm in thickness) of plain carbon steel (S45C in JIS), aluminum alloy (A2017) and copper alloy (C3604) are finished with ceramic media (Equilateral triangular prism 6 mm in side and 5 mm in thickness). The conclusions are summarized as follows; The compound solution has more influences on finishing characteristics than plain water. It makes the relative stock removal larger and the surface roughness smaller than the water. The relative stock removal and the media weight loss on the flow-through system are larger than those on the batch system.

Abstract: This paper proposed an on-machine laser deburring method for narrow slits made by laser cutting. Burrs are generally unwanted materials which remain at the cutting edge after machining operations, such as grinding, drilling, milling or turning. A cost necessary to remove burrs becomes a significant portion of the machining costs. In laser cutting, dross removal was significant problem. It is difficult to prevent completely dross from adhering in laser cutting for stainless sheets. In laser cutting for adornments, it is necessary to remove the dross and to chamfer the cutting edges in order not to injure the hand. It is difficult to remove the dross and to chamfer the edges of a narrow slit by machine work or handwork. We irradiated the defocused laser beam to the slits again for these post-processing. To control the depth and width of the removal area, we examined the relationship between the removal area and the deburring conditions. It was clarified that the width and depth of removal area can be controlled by irradiation time and energy fluence.

Abstract: The size of the photo mask and mother glass used in liquid crystal display production has increased yearly. Large rectangular glass plates are difficult to planarize using rotary-type polishing machines. We have developed a rotary-type polishing machine with tool path control that is optimized by polishing simulation for a rectangular wafer. The present paper describes the planarization of a rectangular plate by simulation. The influence of tool size and the aspect ratio of the rectangular plate on the flatness are clarified. For a square plate, the flatness obtained under optimized oscillation speed is less than a quarter of that obtained under uniform oscillation speed. For rectangular plates with aspect ratios of 1:1.25 and 1:1.5, planarization using a tool having a diameter equal to half the diagonal length of the plate is shown to be difficult because the stock removal distributions in diagonal and short side of the workpiece become the different shape.

Abstract: . A polishing process, which is the final process in manufacturing optical elements, takes a long time and often depends on the experience and special skills. Development of a skill-less polishing technology and automation of its process, therefore, has been required. One of the most promising polishing technologies is Field-assisted Fine Finishing (FFF). In this study, an Electro-rheological Gel (ERG) polishing pad with one-sided patterned electrodes is developed to polish insulator materials and, moreover, a novel electric-field-assisted polishing technology for glass polishing is proposed applying this pad. The ERG polishing pad can change the polishing performance according to applied electric field due to “electro-adhesion effect”. Results of several polishing tests show that the performance of polishing a blue glass can be controlled by applying electric field to the ERG pad.

Abstract: This paper proposes a new dynamic friction polishing method which utilizes resistance heating for solving a problem of too high pressure on a workpiece in the previous dynamic friction polishing method proposed by the authors. In the new method, an electrically conductive diamond workpiece (which has proper electric resistance) is heated by an electrical current flowing from a stainless steel disc tool to the diamond workpiece during the dynamic friction polishing and the polishing efficiency increases remarkably even at a very low pressure on the workpiece. For example, polishing efficiencies of 233 and 800 µm/min are attained at low pressures of 2 and 5 MPa, respectively, at a disc sliding speed of 2500 m/min.

Abstract: This paper deals with the experimental investigation on the detailed performance of MCF (magnetic compound fluid) polishing liquid (MPL) in nano-precision surface treatment of acrylic resin that is essentially required for producing the model in the process of developing an inaugural mechanical system. The MPL is produced in practice by mixing iron powder, abrasive particle and -cellulose fiber into a MF (magnetic fluid), and hence a kind of functional fluid reacting to magnetic fields. Following the previous works confirming the performance of MPL in the surface finishing of acrylic resin, in this work a series of experiments were conducted to reveal how the process parameters affect the machining characteristics in details in order to establish the new technique. The results showed that a mirror surface can be easily obtained once the process parameters have been set up optimally.

Abstract: This study targets the development of a polishing technique that uses a photocatalyst and a fluorescent substance excited by an ultraviolet ray. Nickel (hereafter referred to as Ni) was polished chemically and mechanically at the micrometer level under ultraviolet-ray irradiation. Measurements clarified that TiO2 of 0.1-μm grain size, at which size the excitation by the ultraviolet ray was less influential, mechanically polished the Ni. Cathilon (a luminous dye) chemically polishes Ni. The corrosion of the Ni surface became large under ultraviolet-ray excitation. A flat surface was attained on the Ni by chemical and mechanical polishing using both the TiO2 and cathilon, when was irradiated by an ultraviolet ray.

Abstract: This paper introduces a study on modeling of the wear of composite carbide nozzles in Abrasive Waterjet (AWJ) cutting. The model was built based on many long-term wear test data. In the model, the effects of jet-parameters such as water pressure, abrasive mass flow rate, orifice diameter, and initial nozzle diameter were taken into account. The model can be used for calculation the nozzle lifetime and therefore used for programming the AWJ cost optimization problem. Through the analyzing of the model, the effects of above parameters on the composite carbide nozzle wear were also more understood.