Papers by Keyword: Micro End Milling

Abstract: An analysis of cutting force performance in the micro milling on steel has been carried out based on an experimental work using micro flat end mills on a precision CNC machine tool. It has been found that cutting forces occurred at low feed per tooth are relatively high by assessing the averaged peak forces from the experiments. When feed per tooth is relatively close to tool edge radius, the forces were not growing in linearity with the increasing feedrate. This finding indicates the significance of ploughing phenomenon as an effect of tool edge radius in micro milling.

Abstract: This paper presents the effect of high speed micro end milling parameters on tool vibration during machining of poly (methyl methacrylate) (PMMA). The main focus is to achieve minimum tool vibration by controlling the cutting parameters; spindle speed, feed rate and depth of cut. An empirical model for tool vibration has been developed using Taguchi method. The orthogonal array, signal-to-noise ratio and analysis of variance revealed that high spindle speed is the most influential parameter to increase the level of tool vibration.

Abstract: The analysis of cutting forces plays an important role in the design of machine tool systems as well as in the planning, optimization, and control of micro machining processes. Several parameters influence the cutting forces of which the friction is important in causing premature tool failure. This paper presents a force model that includes the friction force for sliding due to the contact between the tool and workpiece at the flank face. Simulation results were compared with the experimental results of Bao and Tansel [1] showing that the model can satisfactorily represent the cutting forces in two dimensional cutting.

Abstract: In this paper, the effect of minimum chip thickness on cutting temperature in micro-end- milling of aluminum alloy Al2024-T6 using a tungsten-carbide cutter are investigated and analyzed. The three-dimensional coupled thermal-mechanical finite element model is adopted to determine the effects of varying depth of cut on cutting temperature considering size effects. The simulation results show that the cutting temperature in micro-end-milling is lower than those occurring in conventional milling processes. When the depth of cut is approximately 40% of the cutting edge radius, there is no chip formation. The maximum temperature occurs at the contact region between micro cutting edge and workpiece, which shows an obvious size effect. The experimental verification of the simulation model is carried out on a micro-end-milling process of aluminum alloy 2024-T6 with a high precision infrared camera. The influence of various cutting depths on cutting temperature has been verified in experiments. The experimental measurements results are in a good agreement with the simulation results.

Abstract: The micro-end-milling process of aluminum alloy Al2024-T6 has been investigated by numerical simulations and experimental approach. The effects of different tool edge radii on the micro-cutter wear were investigated. A three-dimensional finite element model is adopted to determine the effects of tool edge radii on the effective stress and micro-cutter wear during the micro-end-milling process. It is observed that the the tool nose wears out much more quickly due to the high maximal effective stress occurring in this zone. The experimental verification of the simulation model is carried out on a micro-end-milling process of aluminum alloy 2024-T6. The experimental results of the micro-cutter morphologies are in a good agreement with the simulation results. The experimental results show that the model is suitable for studying the mechanism of micro-cutter wear.

Abstract: The applications of micro end milling have been gradually broadened to meet the ever-increasing demands for micro parts. In micro milling, premature tool failure and short service life are major problems. In this study, micro end milling with ultrasonic vibration in normal direction is investigated. Kinematical analysis is done to describe the exact trajectory of the tool tip when vibration is applied. Based on which, an analytical model of chip formation is proposed. By accurate calculation of instantaneous chip thickness, the cutting forces in micro end milling with and without ultrasonic vibration are predicted and verified by a slot-milling experiment. As a result, it is found that ultrasonic vibration in normal direction is helpful when reducing the cutting force owing to intermittent cutting effect.

Abstract: In micro endmilling, because of small uncut chip thickness comparable to the tool edge radius and low rigidity of tool, the cutting process must frequently transit between rubbing/ploughing and cutting, and it may deteriorate the machining stability, surface finish and tool wear. In this report, such unique cutting phenomena are investigated by modeling a mechanism, computer simulations and experiments. As a result, a possibility of the unique cutting phenomena proposed has been certified.

Abstract: In this study, a serial of dry milling experiments of 6061 aluminium alloy using single edge rhombus micro end mills were performed. The purpose is to examine the influences of various control factors on tool wear. Control factors under investigation include coating layer, side clearance angle, feed rate, and spindle speed. We applied Taguchi method to design the experiment in order to derive an optimum combination of cutting parameters quickly. During the milling test, we fixed depth of cut at 0.2 mm and width of cut at 0.50 mm to investigate the correlation among side clearance angle, feed rate, spindle speed and coating layer. Upon completion of each milling test, the cutting-edge wear and flank wear were measured in offline by the aforementioned tool microscope. The experimental results show that among the four control factors, side clearance turns out to be the most important one. By using TiCN-coating and setting side clearance angle at 10 degree, spindle speed at 6000 rpm, and feed rate at 0.0125 mm/rev, the micro end mills generate least wear and thus have longer tool life.

Abstract: Recently, ultra-precision micro patterns and shapes have been widely used in optical field. Various methods which are based on semi-conductor fabrication methods are nowadays used in fabrication of micro shapes and patterns, but micro endmilling technology has lately attracted considerable attention because of various available materials, flexibility of process and high-productivity. For the precision micro endmilling process, analysis of micro cutting error is mandatory. In general, tool deflection is a major factor which causes cutting error and limits realization of the high-precision cutting process. Specially, in micro endmilling process, micro tool deflection generates very serious problems compared to macro tool deflection. In this paper, it is performed to observe the real tool deflection shapes in micro endmilling process, so the trend of micro tool deflection was analyzed using real captured images in this study. To get the real images of micro tool deflection, micro slot cutting processes were executed under various cutting conditions using micro endmill and the real images of tool deflection were obtained during cutting process by high-speed camera. Finally, the extent of tool deflection was calculated by the deflection angle according to cutting conditions and two trends (the point of first tool contact and the cutting stage) of micro tool deflection were analyzed.

Abstract: We fabricated micro-patterned 2.5-D scaffolds using micro-end-milling with controlled pore and island sizes and interconnectivity to determine the effects of the micro-patterns on the cell culturing process. Micro-end-milling can easily realize a high aspect ratio and accuracy, and can be applied to various materials, including those that are biocompatible and biodegradable. Sixteen types of micro-patterned scaffolds were designed and fabricated using the micro-end-milling process. Fibroblasts were seeded and cultured to examine the viability of the developed micropatterned scaffolds and their absorbed cell adhesion. The results confirmed that the fabricated micro-patterns functioned successfully as scaffolds.