Papers by Keyword: Micro End Mill

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: High speed machining of the corner of hardened steel mould has a great influence to the entire product performance of the mould. In this paper, with the single factor experiments, the influence of feed per tooth, cutting speed and angle of the corner to the cutting forces, the vibration value and the surface roughness were analyzed. And the cutting parameters were optimized. The cutting forces, vibration value and surface roughness value of the corner of the mould reached the minimum value when the cutting speed was 80 m/min and the feed per tooth was 0.006 mm/z in the experiment. The surface quality of corner with angle of 90^o was better than the corner with angle of 60^o and 120^o with various milling parameters.

Abstract: The use of microfluidic devices brings some benefits such as low reagent consumption, shorter analysis time, portability and cost reduction. The potential of this technology has constantly grown over time and lead to the development of competitive manufacture processes. The production of such microfluidic devices is usually done by molding processes which allow mass production of polymer disposables with a low cost per unit. In a prototype phase these methods are, however, expensive. To overcome the multi-step fabrication the direct milling in polymer is an alternative. In this paper micro structures are directly milled in polymethyl methacrylate (PMMA) with self-developed micro end mills and the proper CAD/CAM integration offering a fast response in manufacturing of complex structures even in the micrometer range The direct milling of structures in PMMA with micro tools-diameter 120 μm is a feasible method to produce a physical prototype. The chosen micro end mills and strategies represent a competitive process in a prototyping level by reducing time to market.

Abstract: Micro end mills, for example, smaller than 0.5 mm in diameter have low strength and stiffness. They are rather difficult to be re-sharpened by grinding. Therefore they are usually used until their breakage or are exchanged for a new one when the machining results lose quality. In the previous study [, tool life up to breakage was experimentally investigated under various feed rates and some useful information was obtained to predict tool life considering a sort of bending fatigue. For each experiment, a new tool was used to machine slots till it broke due to fatigue and/or wear. In this study, in order to measure tool life based upon another point of reference, the machining accuracies of the above slots were investigated. The main results obtained are as follows: (1) Slot depth first increased due to thermal deformation of the spindle and then decreased due to tool wear, (2) Slot width decreased as the tool wear increased, (3) Slot bottom corner radius increased as the tool wear increased, (4) Burr size increased as the tool wear increased, (5) Surface roughness of the slot bottom seemed to be influenced by feed rate, tool wear and chatter.

Abstract: There is an increasingly growing demand for fabrication of micro-structured surfaces such as micro lens arrays and micro prism arrays. Micro end milling is one of the most efficient machining technologies for fabricating these microstructures. In this paper, micro electrodischarge machining (EDM) was applied to fabricate single flute micro end mills on polycrystalline diamond (PCD). Using the fabricated end mills, micro end milling tests of dimple arrays were performed on tungsten carbide (WC) molds and the machining characteristics were investigated.

Abstract: This study deals with the cutting characteristics of titanium materials when milled by a small-diameter end mill, or a micro end mill. It is well known that titanium is difficult to cut by conventional means. However, its cutting characteristics have not yet been made sufficiently clear in cases where a micro end mill less than 1 mm in diameter is used. This study chiefly involves the experimental investigation of tool wear and surface roughness of micro-end milling of Ti-6Al-4V. The findings were that tool wear did not increase much when the cutting speed was increased from 50 m/min to 200 m/min. Furthermore, the cutting force required to cut decreased at high speeds and during wet cutting. In wet cutting, the surface had a roughness (Rz) of only 0.3 μm at 200 m/min in contrast to 0.6 μm at 50 m/min.

Abstract: To obtain some knowledge to predict the tool life caused by breakage, a series of slotting experiments was performed at various feed rates for high carbon steel by using coated carbide square end mills of 0.5mm in diameter. The main results obtained are as follows, (1) There found a possibility to obtain an optimum feed rate for the maximum slotting distance. (2) Lower feed rate caused chatter but higher feed rate rarely caused chatter. (3) A newly defined cumulative damage seems to be useful in some extent to predict tool life by monitoring cutting force.

Abstract: The surfaces of Al6061, machined by 150 μm two flute micro end-mills, were studied to determine their roughness. The surface roughness, Ra, was less than 100 nm but the Ra/Rz ratio ranged from 0.03–0.12. The surface roughness was found to improve with increasing width of cut and to a lesser extent with increasing feed rate. A single pass of the end-mill was found to produce a smoother surface than two passes over the same surface. The surface roughness was found to correspond to the diameter of the end mill and the slope of the secondary cutting edge. To reduce the surface roughness, smaller diameter end mills and chip loads should be used.

Abstract: In this study, an approach by the feed rate control was applied for the improvement of form accuracy in the micro end milling process. In this approach called adaptive control constraint, the feed rate is controlled so that the cutting load is constantly kept and the deflection of tool does not occur. However, this method is not always effective in the micro cutting process that the influence of size effect cannot ignore. Therefore, the relationship between the cutting conditions and the form error in the micro end milling is experimentally investigated. The experiments on the machining of metal mold steel with the micro end mill are carried out and the formulation as function of the cutting conditions and the form error is identified by means of regression analysis. The performance of the feed rate control was validated based on experimental results. As the result, it was confirmed that the form accuracy was improved.

Abstract: This paper describes the cutting characteristics and the shape error of groove when PMMA and PTFE are finished by the end mill with small diameter. Direct cutting experiments of micro channel by a miniature end mill were carried out in order to consider the possibilities of the fabrication of micro devices by machining. As the results, it was found that the surface roughness of 1 μm Rz or less was obtained and the width of channel became less than the tool diameter and the deflection of the end mill caused by the cutting force affected the shape error of the groove.