Papers by Keyword: ELID (ELectrolytic In-Process Dressing) Grinding

Abstract: Silicon carbide (SiC) materials have increasingly been needed in the wide range of industries, such as for structural components, automobile parts, space telescope, X-ray mirror, and next-generation semiconductors. However, SiC materials have difficulties in super-smooth finishing because of their hard and brittle characteristics. The authors have been investigating appropriate conditions on their finishing by fine-grinding with the unique grinding process called ELID (Electrolytic In-process Dressing) grinding method. The ELID grinding method has a stable grinding ability, so very detailed characteristics of their material-remove mechanisms were to be investigated. Surface analysis of each material has been discussed through the ELID, and this study proposes good finishing conditions for SiC. In this paper, the advantages of the applied fine-grinding are shown, and unique features on grinding characteristics of SiC through various grinding experimental parameters are described.

Abstract: Progress of new dental materials such as biocompatible metal, ceramics is being accelerated because of aging society and sophistication of medical treatment. In addition, the demand for dental implant treatment is increasing. Currently, dental implant crowns (superstructures) are formed by cutting semi-sintered ceramics and then sintering the ceramics at a high temperature. So, there is some concern that to maintain the form accuracy of the workpiece is difficult. Meanwhile, it is usually difficult to machine sintered ceramics with high precision and high efficiency. In this paper, we tried to apply grinding with metal bonded superabrasive wheels, and investigated the grinding and surface characteristics of an alumina and zirconia ceramics for dental implant superstructure due to lack of such data. As a result of experiments, sintered dental ceramics can be ground with high precision and Fe, it has harmful effect to human body, was not detected in sintered dental ceramics.

Abstract: ELID Grinding, since its introduction over two decades ago, has helped in material removal of hard and difficult-to-cut engineering materials. A gist of the important research milestones on the process has been organized in this report. The hybrid process of ELID Grinding has a simultaneous electrolytic reaction and grinding action. Electrolysis takes place between the conductive anodic wheel and highly conductive cathode in presence of a special electrolyte. The resulting anodic oxide wears off easily to allow efficient grinding. The different parameters involved in electrolysis complicate the mechanism of grinding and makes it significantly different from conventional grinding. Different variants of the process have also been reported, though the basic philosophy of operation is the same as basic ELID. Several authors have also suggested mathematical explanations, among other fundamental studies, that provide further insight. The basic components of the process, machine tool, power supply, grinding wheel, electrode and electrolytes, have also undergone several modifications and developments to deliver better results and suit specific purposes. The process has been successfully applied in stock removal operations for hard and brittle ceramic materials with low grinding forces compared to conventional grinding. Fine finishing of almost all kinds of hard and brittle materials, ranging from hardened steels, BK7 glass, mono-crystalline silicon, silicon carbide, aluminum nitride, silicon nitride etc, has been successfully carried out, to provide high quality surfaces with low sub-surface damage. Finally, discussions on the different stages of evolution of the process have been put forward as a conclusion to the report.

Abstract: Ceramics has many advantages that cannot be substituted by metals, but its machining induced defects, such as crack and crater, are the obstacle of using ceramics in engineering. Thus, the further studies on the materials removal mechanism of ceramics should be done. As known, the cutting theory of metals is very successful and it is helpful to understand the material removal mechanism of ceramics. Through doing comparative experiments, the material removal mechanism of ceramics may be more deeply ascertained. Four types of material, such as ZrO2, SiC, STAVAX and SKD11, were ground by ELID (ELectrolytic In-process Dressing) method in this study. The grinding forces, roughness and topography of the ground surface were investigated. On the basis of this experiment, the difference of material removal mechanism between ceramics and steels was explained.

Abstract: Quartz has excellent optical properties and thus it is often used as the material of mirror and lens. However, it is almost impossible to be machined by cutting due to its brittle and high hardness. Grinding is a common method for machining quartz. One of the authors designed a new type of a paraboloidal mirror of quartz for the neutron optical devices. The fabrication process of this mirror was investigated in this experiment. A jig with two grooves of 90 degrees was made and two workpieces were stuck on the jig using the wax melt at about 60 degrees centigrade. The two workpieces were first ground applying ELID (electrolytic in-process dressing) grinding method with #325 and #1200 cast iron bonding diamond abrasive wheels. Then the ground surface was polished with CeO2 slurry. The finished surface roughness was Ra2.0nm and rms2.4nm and its form error about 2μm. After coating process, its properties of focusing neutron beam were measured. The results were that the reflecting rate was 42%, gain 1.9 and 2.3mm×10.1mm beam focused to 1.6mm×2.1mm.

Abstract: In this study, grinding of Si3N4, SiC, and Al2O3 ceramics under the condition of electrolytic in-process dressing (ELID) system was investigated. The surface appearances of these engineering ceramics during the ELID grinding process were attentively observed to describe the formation of finely finished surfaces. Based on the analysis of material properties and detailed micro-observation of ground surfaces, it can be concluded that the material removal mechanism of engineering ceramic is closely related to its mechanical properties. The silicon nitride ceramic was most easily machined to precision surface among these three engineering ceramics.

Abstract: A new CAD system, which is called Volume-CAD (VCAD) have been developed. We carried out research and development of VCAD fabrication process based on VCAD/CAM precision control. In this study, a developed V-CAM had been used for a polishing fundamental experiment of a free form surface. The relationship between NC resolution and form accuracy of polished surface are discussed.

Abstract: Nano-cemented carbide is a novel material, which is superior to common cemented carbide on physical and mechanical properties, such as high hardness, toughness, flexural strength and higher wear resisting property. It is proposed to have wide application prospect to tools and mould manufacturing. In this paper, ELID grinding technique is applied to grind nano-cemented carbide tools. And the ground surface quality, cutting edge radius, and machinability of nano-cemented carbide tools are studied, compared with common cemented carbide. It is demonstrated by experimental results that nano-cemented carbide has higher grinding surface quality with less surface flaw than that of common cemented carbide. The cutting edge radius of nano-cemented carbide tool is less than that of common cemented carbide tool. Under the same conditions, the tool life of nano-cemented carbide is 1~2 times longer than that of common cemented carbide. The research results indicate that ELID grinding technique is suitable for grinding cemented carbide tools. Nano-cemented carbide tools have better machinability than common cemented carbide tools.

Abstract: The purpose of this experimental research are investigation the growth behaviors of the oxide layer at different pre-dressing conditions in ELID pre-dressing, effects of voltage and duty ratio of the power supply, wheel speed on the oxide layer formation characteristics on the metal bond diamond wheel surface. The results indicated that the oxide layer thickness on the wheel surface increase with pre-dressing time. The oxide layer growth rate is faster in beginning period time of pre-dressing process then slow down. Both the thickness and growth rate of oxide layer increase with the increase of duty ratio and applied voltage. It takes longer time for oxide layer growth rate to reach to stable state in lower duty ratio condition than in higher duty ratio condition. There are no effects of wheel speed on oxide layer growth behaviors in the wheel speed range of 1000rpm to 4000 rpm.