Abstract: An electroformed diamond tool with a tool tip radius of 0.2 mm was developed to achieve a surface roughness of less than 10 nm Rz on a mould made of cemented carbide. A polycrystalline diamond disc with a primary grain size of 0.5 µm and a diameter of 15 mm was used as a truer. A concentric guide groove with a reverse profile relative to the hemispherical tool and a surface roughness of 0.5 µm Rz was preformed on the truer by laser machining and wet lapping. It was verified through a truing test that 93 % of the diamond grains on the tool working surface could be flattened when the tool was placed in elastic contact with a guide groove with a depth of 50 µm. A grinding test revealed that the tool had the potential to efficiently fabricate a ground surface with a roughness of less than 10 nm Rz on cemented carbide with a hardness of 2600 Hv.
Abstract: The error due to tool deflection is detrimental to machining precision. In order to predict tool deflection more accurately, this paper presents a special three segments cantilever beam model for ball-end tool deflection in sculptured surface milling. Different from the traditional two segments cantilever beam method, the ball-end tool is divided into the shank, the flute and the ball-end parts in this new model. Then the ball-end tool deflection is simulated also by utilizing the finite element software ANSYS 12.0 Workbench to calibrate the accuracy of the tool deflection models. The three segments cantilever beam model for ball-end tool deflection matches better the finite element method (FEM). In the last part of the paper, the sculptured surface machining experimental results show that, the surface precision after tool deflection compensation based on the new three segments cantilever beam model is higer than that based on the two segments cantilever beam model.
Abstract: The hierarchical approach of multi-scale modelling was adopted to study the nanometric cutting process of calcium fluoride. Then fly cutting experiments of CaF2 were performed to analyze the influence of cutting speed upon the surface roughness of CaF2. The results of FEM simulations show that larger negative rake angle and larger cutting edge radius lead to lower tensile stress in the cutting region. Tangential cutting force will first increase with an increase of negative rake angle and cutting edge radius, and then start to decrease with them. The tensile stress in the cutting region will increase with cutting depth at first, and then become stable when it reaches a certain extent. The specific cutting force increases rapidly with decrease of cutting depth, showing an obvious size effect. Within the range of cutting speeds adopted in the simulations, cutting speed has little influence on the tensile stress in the cutting region. And the results of fly cutting experiments show that cutting speed has little influence on the surface roughness of a machined surface under the cutting speeds adopted. This verifies the validity of the simulation result to some extent.
Abstract: Ion beam figuring (IBF) is a novel technology for Ultra-precise optics. Material is removed from optic surface in atomic or molecular form by physical sputtering. Due to non-contact between the tool and the work piece, the problems involved in the conventional process are avoided, such as edge-effect and tool-wear. The ion beam figuring process is of high determinacy and high efficiency. All these properties make ion beam figuring one of the promising methods for producing mirrors of high precision with nm-rms accuracy. In this article, a new ion beam figuring system which contains doubled vacuum chambers is set up. Optics can be exchanged by a transport vehicle shuttling between the two vacuum chambers without opening the primary vacuum chamber and waiting for the ion source to cool completely, which means the efficiency can be increased greatly. A high performance processing robot contains three linear axes and two angular axes of motion, providing 5-axis ion source positioning capability with high accuracy. The angle can be up to 50° to figure very steep spherical and aspherical surfaces. Then, the beam removal function of Gaussian shape is obtained by an experimental method and it is extremely stable for a long time. Finally, two sample mirrors are figured by the ion beam figuring system: one is a fused silica flat mirror with a 100 mm diameter (90% effective aperture) and an ultra-precise flat mirror with a surface error of 0.89 nm rms, 14.7 nm PV is obtained; the other fused silica concave spherical mirror with a 100 mm aperture (90% effective aperture) and 420 mm radius of curvature is figured and a concave spherical mirror with 1 nm rms, 16.9 nm PV is obtained, which prove that the ion beam figuring system is favourable for the figuring process.
Abstract: In this research, a polydimethylsiloxane nanostamp for nanocontact printing was fabricated by replicating Si nanomoulds. Si moulds of various shapes and sizes were fabricated by interference lithography and deep reactive ion etching. As an anti-adhesion layer, octadecyltrichlorosilane was treated on Si nanomoulds. Further, superhydrophobic surfaces were obtained by self-assembled monolayer treatment on Si nanostructures.
Abstract: Electrical circuits of Printed Wiring Boards (PWBs) have become multi-layered. Therefore, the formation of micro-blind holes for interlayer electrical connections (blind via holes: BVH) is required. As a result, Cu-direct laser drilling is attracting attention. However, Cu-direct drilling is problematic in that it produces a copper overhang as a result of copper and resin, which have different decomposition points, being melted simultaneously. In addition, the state of PWB surface after the laser drilling is very important. However, this procedure restricts the board density that can be achieved as a result of the limited positional accuracy of the etching process. Consequently, using a Cu-direct drilling process, which does not require etching of the copper foil, to drill BVHs to connect copper foils using a CO2 laser beam has been receiving considerable attention for the next-generation high density PWB manufacturing. However, in the Cu process of generating a direct and overhang problem, there is the problem of accuracy on the substrate surface. In contrast, in-depth research on quality companies has not been performed. Thus, we observe the removal process. Furthermore, we demonstrated reduced overhang.
Abstract: Precision micro-machining without crack and heat affected zones is required in order to use high-performance materials such as silicon and silicon carbide, and it is expected that the higher harmonics of the Nd:YAG laser can perform precision micro-machining due to its high photon energy. However, even by using the harmonics of the Nd:YAG laser, a heat affected zone is inevitable due to the plasma generation. In order to reduce the influence of plasma on the processing results, it is important to understand the generation mechanism of plasma. Therefore, the laser induced plasma in micro-drilling of silicon carbide was observed by a high-speed shutter camera, and the influence of laser wavelength and surrounding conditions on the machining characteristics were experimentally investigated. The removal depth increased with decreasing wavelength and the surrounding gas pressure. The surface integrity was improved by the combination of shorter wavelength and reduced pressure conditions. The behavior of laser induced plasma was different from the wavelength of the laser beam and the surrounding gas pressure. Under atmospheric pressure conditions, the plasma grew greatly and affected the wider surface around the drilled hole with increasing wavelength. Under reduced pressure conditions, there was little difference in plasma size by wavelength, and the affected zone around the drilled hole became relatively smaller. It became clear that a low surrounding gas pressure and shorter wavelength were important to obtain better surface integrity and highly efficient processing.
Abstract: The Winston cone baffle was developed for the space observation camera of the MIRIS (Multi-purpose Infrared Imaging System) which is the main payload of STSAT-3 (Science and Technology Satellite). The Winston cone baffle reduces the orbital heat load to the STSAT-3 and is thermally connected to the radiator to cool down. The jig and ultra precision machining jig was designed using a 3D modelling program and analyzed using a computer aided engineering program (ANSYS). The reasons for designing the jig for the baffle were to enhance the stability of the machining and improve the form accuracy of the baffle. The strength, weight and barycentre of the jig are investigated to find the optimized ultra precision machining conditions. To maintain the weight balance of the baffle at high speed rotation, there are lots of holes that can be inserted by heavier bolts. Vibration of the natural diamond bite tool is reduced by using thin copper pipe and urethane silicone. Using this bite tool, we could decrease patterns on the surface of the Winston cone baffle. The results of the simulation using ANSYS show that maximum deformation of the baffle is less than the tolerance limit. Surface roughness of the fabricated Winston cone baffle is machined with the jig and the machining tool is under 5 nm. The Winston cone baffle is plated with gold after being electroless plated with nickel. This baffle is applied to the flight model of the MIRIS.
Abstract: In this paper, we describe the development of a needle based dispenser for high-viscosity liquid, and pick & place of micro objects using capillary force. Recently, miniaturization of portable devices and their electronic parts has been remarkable. So we think that there are a lot of needs for micro manipulation for making more complex and smaller devices. There are a lot of possibilities to manipulate complex-shaped micro objects by using liquid because it changes its shape flexibly according to the shape of the contact surface.
We have developed a unique surface mounting technology which is based on a movable shaft driven by a piezoelectric linear motor. We can simply apply high-viscosity liquid drops by stamping the wet tip of the shaft on a substrate, and we confirm that the device is able to apply a liquid the viscosity of which is about 1200Pas. We have studied the relation between viscosity and diameters of applied liquid drops via several experiments. We have also conducted interesting experiments in which we pick and place some small and complex-shaped objects using capillary force. We confirmed that if capillary force between the shaft and micro object is larger than that between the substrate and the micro object, we are able to place a chip-capacitor weighing below 1 mg. This simple method is very effective because any shaped object can be mounted. However, fast control and accurate control of the shaft are needed for efficient production and accurate mounting. To realize this, we developed a PID controller for the dispenser with an optical liner encoder with a resolution of 30 nm. We confirm that settling time becomes less than 50 ms when the shaft moves 5 mm with 1 micrometre accuracy.