Papers by Keyword: Tool Wear

Abstract: An attempt is made to reduce the process forces and tool wear during friction stir welding of 409M ferritic stainless steel and to enhance the mechanical properties by induction preheating of base metal with different preheating temperatures at the leading of tool. It is observed that the preheating significantly decreased the longitudinal and axial forces. Tool degradation analysis was carried out to find out the loss of tool profile and material. Mechanical properties especially impact toughness values were increased due to significant reduction in the tool wear.

Abstract: As the requirements of MEMS continuously increase, the micro ceramic structures are widely used due to their favorable material properties such as high strength, hardness and resistance to high temperature, wear and erosion. However, the sintered ceramic compact is hard to be machined as its high strength. On the other hand, the low strength of green ceramic body makes it difficult to guarantee the machining accuracy. In this paper, ceramic compacts are pre-sintered below the sintering temperature. Pre-sintered ceramic compacts have suitable strength and are easy to be machined. Simple ceramic micro structures are easily generated with micro tools fabricated on line by wire electrical discharge grinding method (WEDG). Extensive experiments are carried out to investigate the influence of the strength of pre-sintered ceramic compact on the tool wear. It was found that the best machining results are achieved under the conditions of using the tool with a semi-circle cross section, the tool rotation speed of 1500 rpm and the pre-sintered ceramic compact formed under the pressure of 150MPa within the range of experimental conditions in this study.

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: Recently, increasingly high efficiency and high performance have become to be required of information equipment. As a result, optical scanning parts that reduce optical aberrations, scatter, and diffraction are required in laser printers. It is therefore necessary to improve the geometric surface roughness achieved in mirror cutting of Al alloys and eliminate tear-out marks and scratch marks that can be created during the cutting process. In this study, we investigated the effect of tool wear on the occurrence of surface discontinuities in ultra-precision cutting of Al alloys. In our previous studies, a crystal orientation of {110} plane was adopted in cutting an Al-Si alloy (AHS material, 11wt% Si) and Al-Mg alloy (A5186 material, 4.5wt% Mg) using a straight diamond tool. The cutting edge recession that occurs when cutting AHS material has been reported to be approximately 5 times greater than that which occurs when cutting A5186 material. Therefore, we cut the AHS material for accelerated wear and investigated the cutting edge recession, the surface roughness and the cutting force. We found that the cutting edge recession decreases as the tool wear angle γ increase. For example, at a tool wear angle γ = 40°, the cutting edge recession is approximately 7 times greater than that which occurs at a tool wear angle γ = 12°. As the tool wear angle increases, the cutting distance increase, which produces a mirror like surface. In addition, we were able to obtain a good machined surface using a positive tool setting angle because side cutting edge produces residual stock of removal 0.1 μm when the cutting edge recession is 0.3 μm or more and when it is cut by following end cutting edge.

Abstract: Micro-channel chips used in micro total analysis systems are attracting attention in medicine. In generally the photolithography technology used in semiconductor manufacturing is used to manufacture micro-channel chip Si-dies. However, this technology requires many processes, such as mask fabrication and the application of photoresist to a substrate as well as expensive clean room facilities. A micro-channel chip has a micro-groove 30–100 μm wide. This study examined how to form a fine groove by cutting with a micro-endmill, with the aim of shortening the window time and reducing the cost. This steel die requires high accuracy, for example, a burr area ratio of not more than 5% of the groove bottom area, a surface roughness of the side and bottom faces of less than 1μmRz, and a change in the sectional area of less than 1%. So, this study examines micro-endmill’s cutting conditions, for example cutting speed, feed per tooth, and axial depth of cut. In MQL (minimum quantity of lubricant) cutting, the early fracture occurs when cutting was began. The cause has bad removing of the chips in MQL cutting, it is considered that the chips of hardened work have been re-cut as the result. Therefore, this study applied ultrasonic cavitation to milling, in order to solve this subject. This report experimentally examined the cutting performance of ultrasonic cavitation-assisted milling. We obtained the following results. In cutting distance of 20 m, the burr of MQL cutting is generated more than 5%, on the other hand, the burr of ultrasonic cavitation-assisted milling is less than that. In ultrasonic cavitation-assisted milling, a tool wear and fracture can be decreased by improvement of removing chips and lubrication.

Abstract: Ni based heat-resistant alloys have high strength at high temperature. In addition, they have low thermal conductivity and work-hardening properties. Therefore, Ni based heat-resistant alloys are known as a difficult-to-cut material. The final goal of our study is to develop a cutting method for extending the life of cutting tools for Ni based heat-resistant alloys. As a first step, this study investigated the size effect in machining on initial tool wear in Ni based heat-resistant alloys cutting. Using two types of Ni based heat-resistant alloys with different average grain size, orthogonal cutting tests were performed under changing uncut chip thickness from 12.5 to 200 μm. The cutting speed and width of cut were 30 m/min and 1 mm, respectively. As a result, it was found that when the uncut chip thickness is less than the average grain size, the initial tool wear strongly depends on the average grain size. In contrast, when the uncut chip thickness is sufficiently larger than the average grain size, the initial tool wear does not depend on the average grain size. These results indicate that the ratio of the uncut chip thickness to the average grain size is an important factor to extend the life of cutting tools for Ni based heat-resistant alloys.

Abstract: This paper presents a novel concept for extending the life of the tools that are used in the milling process of carbon-fiber-reinforced plastic (CFRP) composites. Three types of tools were compared in milling tests; tool I: an uncoated tungsten carbide (WC-Co) tool, tool II: a polycrystalline diamond (PCD) tool, and tool III: a combination tool comprising a PCD layer surface with a thickness of 100 μm and a WC-Co substrate flank surface. The measurement of changes in cutting forces over cutting distance revealed that tool III had a better (tool) life performance than the other tools. Additionally, observation of changes in the edge profiles of the tools revealed that the effective edge sharpness of tool III remains constant during the milling tests. The difference between the wear rates of the PCD rake and WC-Co flank surfaces in tool III maintained a constant effective sharpness during the milling process, and it extended the tool life. Based on our findings, we concluded that using the difference between the wear rates of rake and flank surfaces is an effective technique for tool life extension in the milling process of CFRP laminates.

Abstract: The high-pressure coolant supply cutting has attracted attention from a viewpoint of chip evacuation and tool life. In this study, the influence of high-pressure coolant supply on chip shape, cutting force and tool wear were investigated. The tests were carried out during external turning of stainless steel with cemented carbide cutting inserts. The results suggest that the length and radius of the chips got shorter with high-pressure coolant supply, especially supply pressure more than 5MPa. The cutting force was increase slightly with high-pressure coolant supply. However the thrust force was decrease. The uniform flank wear and crater wear were reduced and tool life was improved by high-pressure coolant supply.

Abstract: In this paper, driven rotary cutting of maraging steel was carried out and the influence on tool wear of difference cutting conditions was investigated. As cutting conditions, different coolant conditions, cutting speeds, circumferential velocity ratios, tool inclination angles, tool rotation directions and normal rake angles were tested. We found that as the coolant quantity decreased and cutting speed increased, the width of flank wear increased. It was also found that the circumferential velocity ratio, tool inclination angle, tool rotation direction and normal rake angle have optimal conditions that decrease wear. Optimal conditions were chosen, and a tool life test was carried out. As a result, driven rotary cutting was achieved with 11 or more times the tool life of conventional turning.

Abstract: This paper is related to the air jet assisted machining method for a titanium alloy, Ti-6Al-4V ELI. The air jet assisted machining method is a new machining method, in which jet of the compressed air is applied to a tool tip together with flood coolant for reducing tool wear and also for extending tool life. In this experimental study, the new method was used in high-speed end milling for confirming the effect on tool life extension. Also, the optimal position of the jet nozzle was found. It was spotted that the new method is highly effective in reducing tool wear even at a high cutting speed. It is particularly noticeable that flank wear near the corner land, which is often severely damaged, was considerably reduced by the method. It turned out that the cutting forces and the degree of surface roughness observed through this method were almost the same as those through an ordinary method with flood coolant alone.