Abstract: Stainless steel is an excellent material that has properties such as heat and corrosion resistance. Thus, stainless steel is used as a material in steam turbine blades. Steam turbine blades are mainly manufactured using two methods. One is the cutting of unforged metal ingots. Another is the cutting of forged parts. Small blades are made by cutting metal ingots. Large blades are made by cutting forged parts. The mechanical characteristics of a metal ingot and a forged part, such as hardness and toughness, are almost the same. There were not researches related to a relationship between “an unforged ingot and a forged part of stainless steel” and “the differences of the tool wear and the finished surface by high-speed milling”.In this study, the high-speed milling of stainless steel was attempted for high-efficiency cutting of a steam turbine blade. The differences of the tool wear and the finished surface in the cuttings of an unforged ingot and a forged part were investigated. In the experiment, the cutting tool was a TiAlN coating radius solid end mill made of cemented carbide. The diameter of the end mill was 5 mm, and the corner radius was 0.2 mm. The cutting speed were 100 m/min-600 m/min. The workpieces used were a metal ingot and a forged part of stainless steel. In the results, it was found that the differences of the tool wear and the finished surface in the cuttings of an unforged ingot and a forged part. In the case of the unforged ingot, the flank wear became large with increasing cutting speed. On the other hand, in the case of forged part, the flank wear rapidly increased at a cutting speed of 100 m/min. In addition, the flank wear became smaller than the cutting speed 100 m/min at the cutting speed 200 m/min. Further, the flank wear became large with increasing cutting speed at cutting speeds higher than 200 m/min. That is, the flank wear was at a minimum at a cutting speed of 200 m/min. Although it could not be confirmed the characteristic of high speed milling at an unforged ingot, it has been identified at a forged part.
Abstract: This paper proposes a roller burnishing method that controls the sliding direction of the burnishing tool on the surface of cylindrical workpiece. In this study, the sliding direction was set by inclining the axis of the burnishing tool with respect to the axis of the workpiece and by actively rotating the roller of the burnishing tool. The workpiece was a cylindrical aluminum alloy bar, which was rotated in a bench lathe. The burnished surfaces at several sliding angles between 15º and 90º were evaluated. The sliding direction, which is set according to a theoretical equation, was experimentally obtained for every sliding angle in the range of 15-90º with respect to the circumferential direction of the workpiece. The sectional profile was flattened and surface roughness was decreased with increasing sliding angle. As a result, the burnished surfaces obtained in this work were superior to those obtained in an earlier study by the authors, in which the burnishing tool was not actively rotated.
Abstract: In this study, tool edge temperature was measured by a two-color pyrometer with an optional fiber. During one revolution of spindle, the tool edge passes over the fine hole at workpiece after cutting workpiece. An optical fiber inserted into the fine hole transmits infrared ray radiated from tool edge to two detectors with different spectral sensitivities. One peak signal from each detector can be obtained by each spindle revolution. The tool edge temperature can be calculated by taking the ratio of outputs from these two detectors. The relation between cutting heat calculated from cutting force and tool edge temperature was discussed. The tool edge temperature at the same cutting heat could be compared. The wet cutting condition caused lower tool edge temperature than the others at the same cutting heat. MQL and dry showed almost same tool edge temperature. The dispersion of tool edge temperature in wet cutting is wider than that in dry cutting and MQL cutting.
Abstract: Micro-channel chips used in micro total analysis systems have been attracting attention in the medical field. Photolithography, which is a technology used in semiconductor manufacturing, is used to manufacture micro-channel chip dies. This technology requires many processes, such as making photomasks, applying photoresist to a substrate, and the availability of expensive clean-room facilities. Micro-channel chips have ‘micro-channels,’ which are micro-grooves having a width of 30–100 μm. These fine grooves require high accuracy in manufacture; for example, the surface roughness on the bottom face is 1.0 μmRz. A previous study showed how tool run-out on the order of several μm incurred during micro-groove milling, reduced machining accuracy, and tool life. To bridge that gap, this study investigated how to form a fine groove by using micro endmilling. Specifically, a method was experimentally examined for reducing the influence of tool run-out on machining accuracy by using two types of endmill—two-tooth square and ball—by modifying the tool setting angle. Modifying the tool setting angle improved the surface roughness of one side of the groove, and reduced change of cutting force in two-tooth square-endmilling. In addition, it was able to reduce the influence of groove width on tool run-out by up to 1/10. A modification of tool setting angle in ball endmilling reduced the influence of tool run-out on machining accuracy.
Abstract: Recently, high efficiency and performance have become necessary attributes of information equipment such as laser printers. Thus, demand has increased for optical scanning parts that reduce optical aberration, scatter, and diffraction are required in laser printers. Polygon mirrors are manufactured by polishing a plating or glassy material to a mirror finish. In this study, we shortened the manufacturing process to improve the productivity and ultra-precision cutting technology of polygon mirrors made of aluminum. Thus, we had to reduce the geometric surface roughness achieved by mirror-cutting Al-Mg alloy and remove tear-out and scratch marks that occur during the cutting process. We investigated the cutting edge shape by using a straight diamond tool to decrease the surface defects produced during the ultra-precision cutting of Al-Mg alloy. We examined the mechanism for the occurrence of scratch marks and a method to reduce them. First, we measured the shape of the scratch marks and the cross-section with a scanning electron microscope. We found the tool collides with crystallization to produce small pieces, which then cause scratch marks. We developed a triple-facet tool with a double-facet at the end cutting edge to remove scratch marks and investigated the influence of surface defects. We clarified that using the triple-facet for a tool setting angle of 0° to 0.04° could achieve a good-quality machined surface without tear-out and scratch marks. In addition, the undeformed chip thickness was less than 80 nm
Abstract: Aluminum alloy die casting products are used for automotive LED lamp installation parts. The high aspect ratio shape used for large-volume heat problems needs thin rib parts. In the present study, we obtained basic data for the development of long axis type end mill tools for electrical discharge machining carbon material processing. At the same time, to evaluate the prototype development work, a special tool that enables high aspect ratio thin rib geometry processing was used. Longitudinal direction traverse cutting was done with a small diameter ball end mill tool in the carbon material for electrical discharge machining mold. The transfer accuracy and pick feed shape in the finished surface, the cutting resistance force, and the cutting edge shapes were examined to clarify the relationship between the cutting conditions set. Prototype development of the small-diameter end mill tool with a high rigidity, long axis was done using FEM numerical analysis method. The results showed that the small-diameter ball end mill tool with a tapered length axis in the prototype development had transfer accuracy of the cutting edge shape, and it was possible to reduce the finished surface roughness. Factors such as differences in tool shape are considered to greatly affect the tool rigidity.
Abstract: Built-up Layer (BUL)/Built-up Edge (BUE) formed on the tool surface can be treated as a protective, thermal barrier or lubricant films especially in the extreme severe conditions when machining the metal materials, which can sustain the tool effective and wear resistance. In order to have a thorough understanding of the adhesion effect during machining, experiments have been carried out to investigate the performance and the formation mechanisms of adhering layer on the carbide tool in machining of aluminium alloys A6063, carbon steel S45C and difficult-to-cut hardened steel S45C (H-S45C). The morphology of tool adhered surface was examined by employing Scanning Electron Microscopy (SEM), the dimensions of adhering layer were measured by Laser Scanning Microscopy (LSM) and the elements on the tool were analyzed by Electron Probe Micro Analyser (EPMA), respectively. The atomic-scale cluster adhesive friction model is proposed to explain the tool-chip contact conditions, which considers the nature of the shear strain, shear strain rate and temperature distribution in the secondary deformation zone. The model is a dynamic model and the rate equation approach can be applied to estimate the formation process of adhering layer during machining. Results have shown that the adhering layer will give rise to BUL on the tool rake face and the BUE on the cutting edge and clearance face.
Abstract: This study described the effect of mechanical properties on the roundness of a drilled hole in the drilling of low-rigidity workpieces. A thin-thickness part workpiece model involving a beam plate structure fixed on both ends was used in the study. The effects of feed, workpiece length, distance from the fixed end to the drilling point, and mechanical properties of the workpiece on the roundness of the hole were investigated. The thrust force increased with feed and the roundness became worse with feed. The hole was enlarged in the longitudinal direction of the workpiece at the upper section of the hole. An increase in the workpiece length decreased the rigidity of the workpiece and deteriorated the roundness of the hole. The roundness error was extremely small when the drilling point was near the fixed end. Carbon steel, aluminum alloy, stainless steel, and titanium alloy were used as workpiece materials. The thrust force in the drilling of titanium alloy and stainless steel was considerably larger than that of the carbon steel and aluminum alloy. The roundness of the hole was worse in the drilling of titanium alloy and stainless steel than that in the drilling of carbon steel and aluminum alloy. Plastic deformation occurred in the workpieces made of titanium alloy and stainless steel, which is probably because the workpiece was yielded by the large thrust force. The value of the ratio of the thrust force in drilling to the Young’s modulus of the workpiece was used in evaluating the deflection of the workpiece and the roundness error of the hole in drilling.
Abstract: In the hole drilling process, produced chip cannot be released from the inside hole which leads to broken glass plate due to the adhered chip on tool. Chip discharge method was announced by many researchers. However, the method using the tool-only with drilling command is rarely seen. In this laboratory, we have developed a tool in order to discharge chip. The developed tool is capable in preventing chip adhesion and producing high quality and efficient hole drilling process. The developed tool has several hundred times longer tool life than a conventional tool. However, the amount of adhered chips on cutting tool increase as the number of hole drilling process increases. The chip adhesion condition is different according to the kind of grinding fluid. Adhesion of chips on tool can be related to the properties of grinding fluid. Thus, in this study, the types of grinding fluid used during the hole drilling process were investigated to determine the state of chip adhesion. Three types of grinding fluid used are Emulsion, Soluble and Solution and all of them include surfactant which is considered to have an effect on prevention of chip adhesion. The main conclusions obtained in this study are as follows. Chip adhesion state was investigated after drilling process and it was found that instead of grinding fluid properties, surfactant also has significant effect on chip adhesion on tool by absorbing the adhered chip from the tool. The results showed that grinding fluid with long-chain surfactant has small amount of chip adhesion whereas grinding fluid with short-chain surfactant has large amount of chip adhesion. Therefore, it can be concluded that grinding fluid with long-chain surfactant is capable in preventing chip adhesion during hole drilling process.