Kazuya Kato

Influence of Scratch Marks on Undeformed Chip Thickness in Ultra-Precision Cutting of Al-Mg Alloys

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

Influence of Micro End Mill Tool Run-Out on Machining Accuracy

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.

Influence of Tool Wear on Cutting Characteristics in Ultra-Precision Cutting

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.

Tool Wear Characteristics in Near-Dry Cutting of Ni-Based Superalloy

Recently, high-combustion-efficiency jet engines have become required in the aircraft industry. High burning temperatures are necessary to maximize the combustion efficiency of jet engines. Inconel 718, which has excellent mechanical and chemical properties, has been selected for use in many jet engine parts. However, Inconel 718 is a difficult material to cut because of its low thermal conductivity. Consequently, wet cutting is typically used to reduce the heat generated in cutting Inconel 718. Wet cutting, which uses a large amount of cutting fluid, is costly and requires considerable energy for maintenance and disposal of the cutting fluid, making this cutting method environmentally unfriendly. To reduce the associated cost and environmental load, the near-dry cutting method, which uses a very small amount of cutting fluid, may be preferable for cylindrical cutting of Inconel 718. However, this method has some drawbacks, such as the cutting stock removal rate and the wear on cemented carbide tools. For example, the cutting stock removal rate is lower than with wet cutting because cutting edge fracture occurs easily in near-dry cutting. In this study, we conducted experiments to examine the relationships between the tool materials, cutting speed and tool fracture in near-dry cutting and wet cutting, and we compared the results obtained using the two cutting methods. We found that an S05-type cemented carbide coating can reduce tool wear. We also found that in the early stages of cutting, between cutting speeds of V = 50 and 90 m/min, the tool wear can be comparatively reduced.

Study on Ultrasonic Cavitation-Assisted Micro-Endmill Milling

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.