Papers by Author: Katsuhiko Sakai

Abstract: This study describes the effects of machining parameters on the thermal affected zone (heat-affected zone; HAZ) of carbon fiber reinforced plastic using fiber laser. The HAZ described in this study was defined as the area where only resin was removed. In three experiments, the HAZ area and the removal shape of carbon fiber were investigated. The study revealed that pulsed laser reduces the HAZ more than continuous-wave laser does, but it causes the swelling of the carbon fiber tip. Furthermore, the HAZ decreased as the scan speed increased, even if the number of scans was increased. In addition, it was found that nitrogen could restrain the HAZ and the swelling of carbon fiber.

Abstract: This paper discusses the development of an in-situ, real-time tool wear monitoring system using the cutting sound that occurs during machining. In this study, the turning of carbon steel was implemented to examine the relationship between tool wear and the waveform of the cutting sound. Characteristic waveforms were extracted by fast Fourier transform (FFT) analysis of the cutting sound. The results indicated that the sound pressure of a specific frequency range increased during the progress of cutting-tool wear. In addition, it was possible to monitor the progress of tool wear by measuring the spectrum of a specific frequency range, even if the shape of the tool rest and the shapes of the work material were different, under certain cutting conditions.

Abstract: This paper describes the effect of oil-immersion treatment on the surfaces of cutting tools. In this study, the ‘oil-immersion treatment’ refers to the modification of the tool’s surface by immersing the tool in a treatment solution and heating under pressure. Our previous study demonstrated that such treatment reduces the wear on cutting tools. In this study, the effect of oil-immersion treatment on a carbide cutting tool was investigated by EPMA (electron probe microanalysis) and XPS (x-ray photoelectron spectroscopy). SEM (scanning electron microscope) and EPMA examination revealed that oil-immersion treatment reduces the amount of cobalt on the tool’s surface and forms sulphur deposits. XPS analysis of the chemical bonds on the surfaces revealed the presence of cobalt sulphide and inorganic carbon. In addition, friction tests showed that the oil-immersion treatment reduces the friction coefficient of the tool.

Abstract: This paper investigates the effects of using nitrogen gas on Mist cutting. In this study we tried to improve the cooling effect of mist on cutting by using N2 gas to assist cooling. As a result, tool breakage was prevented when using carbide tools and a large reduction in tool wear was confirmed when using cermet tools. Our conclusion is that N2 gas assisted mist cutting reduces oxidation wear, which means that the cutting characteristics are better than in conventional mist cutting.

Abstract: This paper describes the effects of novel nitriding technique used in various carbide cutting tools. In manufacturing, eco-friendly machining is demanded of late. So far, many kinds of methods were made practical, for example MQL process. Through the development of coating technology, dry cutting process has been used and even now more improvement of tool life is required. Both coated and the non-coated carbide tool were applied with novel nitriding to elongate their tool life. The results show novel nitriding decreased the coated carbide tool wear and improved its tool life 1.4 times longer than non-treated carbide. Similarly, the non-coated carbide tool wear decreased and built-up edge on tool surface reduced. These improvements may be derived from the hardening effect on the binder material within the carbide tools.