We are engaged in the development of eco-friendly ELID grinding technology, and have manufactured a conductive carbon bonded diamond wheel for ELID grinding using plant carbon. A nonconducting layer was formed on the carbon wheel surface by electrolytic dressing. The layer has a high friction coefficient, and the layer on a reed carbon wheel has high wear resistance compared with that on a water hyacinth carbon wheel. A plant carbon resin bonded diamond wheel using #1200 abrasive grain was manufactured for the grinding experiment. In the grinding experiment with single-crystal silicon, the surface roughness was set to Ra: 5.2 nm for the combination of plant carbon wheel and ELID grinding.

View full abstract

Due to the retirement of many middle-aged technicians, it is becoming important to pass on their skills to the younger generation. To support the passing on of these skills, a "process template," which can visualize, reveal, and store skills related to cutting techniques, has been developed. The process template is constructed with a flowchart to demonstrate sequences of machining process and tables to represent the detailed conditions of machining. To skills related to the milling of thin sheet metal are stored in the process template and applied in small- and medium-sized enterprise environments. The process template allows younger engineers to perform machining successfully because the template demonstrates how a skilled technician fixes the low-stiffness work material.

View full abstract

The first report described the cutting force, specific energy, and depth of cut for a single grain found during ductile-mode grinding of BK7 glass. To achieve a more intermittent machining process, the application of thrust force directional vibration was demonstrated. Here, a single-crystal silicon wafer (1,0,0) surface was ground with and without thrust force directional vibration-assisted grinding. The normal grinding force of grinding with vibration showed a comparatively low value, but was quite stable. The removal rate was about 3 times that without vibration. Further, in a fly-cut experiment, single-crystal Si could be cut in ductile mode using a single cutting edge with vibration. The removal process by successive cutting edges was determined by the cutting conditions including vibration. The results of this study suggested that a multi-cutting tool with uniform cutting space is required to achieve more effective ductile-mode machining with thrust force directional vibration.

View full abstract

This study was performed to clarify the friction and wear phenomena important in abrasive machining with atomic-scale material removal, such as polishing of magnetic disk substrates and CMP of semiconductor substrates. Here, various phenomena in the region from sliding to atomic removal on a well-defined copper workpiece surface by an extremely fine rigid diamond abrasive were analyzed using a molecular dynamics model in which an abrasive grain is connected to a three-dimensional apring and holding rigidity of the abrasive grain is taken into account. A series of simulations under several indentation depth conditions clarified that the one- or two-dimensional atomic-scale stick-slip phenomenon in proportion to the period of atomic arrays of workpiece surface occurs in sliding processes withouto atomic removal. On the other hand, it was also demonstrated that the period and amplitude of stick-slip phenomenon vary when accompanied with atomic removal due to the increase in normal load. These are specific phenomena in such abrasive machining processes at the atomic-scale.

View full abstract

The diamond wheel with a diameter within several millimeters has the disadvantage that it is difficult to improve the surface roughness, because the circumferential speed of the wheel is slow and the number of grains on the wheel is low. To suppress the decrease in grain number, a thermoplastic resin was chosen as a bonding material. This material softens on heating and solidifies again when cooled. A method of returning the abrasive grains to the wheel with the possibility of dropout was developed using heat under grinding. In this paper, a newly developed thermoplastic resin-bonded diamond wheel and a conventional thermosetting resin-bonded diamond wheel were tested under the same conditions, and their performances were compared. The arithmetic-mean-deviation of the profile of the newly developed diamond wheel was 51% of the value of the conventional diamond wheel at the first stage of grinding. The wear volume of the new wheel was a 57% of the value of the conventional wheel.

View full abstract