Papers by Author: Yasuo Yamane

Abstract: Behavior of the material adhered to the cutting edge of a cermet insert was evaluated based on the profile of the machined surface in continuous turning of an austenite stainless steel SUS304. Height of the adhesion material decreased rapidly with increase of the cutting speed from 10m/min to 20m/min. The behavior of the adhered material was more stable than we expected. The adhered layer near the cutting edge was very stable, while the growth or breakage of the adhered material happened on the surface of the stable layer.

Abstract: In the 1960s, Opitz discovered the formation of complex oxide protective layers (Belag) on worn surfaces of tools when cutting Ca deoxidized steel. Belag formation is used in a free-cutting technique for steel and cast iron because it significantly reduces diffusional wear by preventing direct contact between the tool and work material; hence, tool life can be dramatically prolonged. For Belag to form, one condition is that the tool material should contain TiC. It has been reported that Belag adheres to tool surfaces because TiC in the tool oxidizes and reacts with Belag. Our study aims to clarify the formation and adhesion mechanisms of Belag. In this study, Ca deoxidized steel was machined with noncoated carbide P10 tools, and the state of the interface between the tool and Belag layer was investigated by transmission electron microscopy (TEM) and elemental analyses. As a result, we found that Belag directly adhered to Ti carbide (Ti–W–C) particles on tool surfaces. In contrast, Belag did not directly adhere to WC or Co on tool surfaces. Unlike previous studies, we could not confirm the formation of the TiC oxide or its oxide layer near the interface to which Belag adhered. In addition, when we machined a Ca deoxidized steel containing MnS, a CaS layer formed in Belag at the interface between the tool and Belag layer.

Abstract: The requirement of the ultra-precision machine tools for ductile cutting of hard brittle materials was examined experimentally. One of the essential factors of achieving ductile mode cutting was not only high-resolution feedback control but also the dynamic performance of the machine tool in forming solid immersion lens of monocrystalline silicon. We also proposed newly developed method for ultra-precision machine tools, which does not have enough high dynamic performance in order to achieve ductile mode cutting of the hard brittle materials. An additional device consisted of air slider on the machine tool was applied to cutting of glass in order to keep stable ductile mode cutting. We fabricated high-value added structure, which are designed a diffraction grating, consisted of micro groove on a borosilicate crown glass surface with the developed device.

Abstract: This paper focuses on the influence of difference of tool materials on generation of wear protective layer when turning gray cast iron containing Al and Mg. In this experiment, the gray cast iron to which small quantities of Al and Mg was added were cut with cermet, P grade carbide (P10), silicon nitride ceramics (Si3N4), titanium nitride (TiN) coated carbide and K grade carbide (K10) at high speed. In turning gray cast iron containing Al and Mg with cermet, the tool wear was significantly reduced compared to that resulting from the cutting of conventional gray cast iron. Further, the protective layer consisting of nonmetallic inclusions in the work material was formed on the tool surface. In addition to cermet, this layer was formed on tool surface of Si3N4 and TiN coated carbide. The elements of Al and Mg added to the work materials were detected in the layers formed on these tool surfaces as well as cermet. The inhibiting effect on tool wear was also caused when turning with P10. However, P10 had much greater wear than cermet. On the other hand, in the case of turning with K10, the effect reducing wear with the addition of Al and Mg was not caused. The wear increased as cutting speed increased regardless of work materials.

Abstract: A new method for evaluation of adhesion in cutting is proposed. Adhesion of chip induces fluctuation in chip flow or stick-slip movement of chip, so that dynamic component of cutting forces depends on the cutting conditions and properties of the work materials. In this investigation continuous turning of a medium carbon steel was carried out and dynamic components of cutting forces are measured by piezoelectric dynamometer. Fluctuation in dynamic force on rake face of the tool is considered at a range of cutting speeds under dry condition and oil-mist lubrication. Surface profiles of machined surfaces and sticking of chip on tool face were also investigated. In cutting of medium carbon steel, the dynamic components below 500Hz increased under the condition of build-up edge (BUE) formation, and gradually decreased as increase of cutting speed. Tool-edge geometry well transferred onto the machined surface when the dynamic components were low level. Smoothness of chip flow on rake face is strongly associated with good surface finish.

Abstract: Stainless steel SUS304 is one of the typical difficult-to-cut materials due to strong tendency to adhesion and work hardening. Therefore finished surface becomes rough in machining operations. In this report, precision cutting of SUS 304 is discussed. Surface roughness depends on accuracy of the machine tool, adhesion and roughness of tool flank. We analyzed the factors of surface roughness in turning of SUS304 on an engine lathe. M20 tungsten carbide inserts, coated carbide inserts and cermet inserts were used. Peak-to-valley height of machined surface included approximately 1μm of machine error. Surface profile reflected roughness of tool flank. Polished flank decreased the roughness of finished surface. Adhesion was least in the case of cutting with cermet inserts. We also conducted face turning of SUS304 on an ultra-precision lathe with cermet inserts. Flank of the inserts were polished to 100nmRz. We obtained 50nm of minimum peak-to-valley height and 220nmRz of surface roughness.

Abstract: Gloss evaluation of a metal surface is important for the quality as the product. In general, gloss of a metal surface is influenced by specular reflection of light on the surface. Therefore to evaluate the specular reflection is almost the same as the evaluation of the gloss. We propose the method to evaluate the specular reflection using patterned area illumination. In the specular reflection, the angle of incidence is equal to the angle of reflection. Consequently when lights (rays) of the area illumination which has a stripe pattern are projected to a glossy metal surface, the stripe pattern occurs on the reflection image by the mirror-like reflection and the sharpness of the stripe pattern of the image has information of the specular reflection on the surface. This character is applied for the metal surface with hairline. The metal surface with hairline has different gloss feeling at different point of view. When the direction of the stripe pattern of the illumination is changed, the sharpness of stripe pattern on the reflection image varies owing to the surface roughness of hairline. Therefore we can evaluate the glossiness for various directions by rotating the stripe pattern. This paper shows the availability of the proposed method through the experiment.

Abstract: Truing and dressing are time-consuming processes in precise finishing with super-abrasive wheels because of the hard super-abrasive grains which cause extensive wear of truer. In this paper, laser-assisted truing method for super-abrasive wheels is introduced. Feasibility of the proposed method is confirmed by fundamental experiments conducted with metal-bonded diamond wheel and pulsed Nd:YAG laser. On the surface of wheel irradiated with laser beam, it is found that the abrasive grains are degraded and the machinability of surface layer is remarkably improved.