Nobuyuki Moronuki

Effect of Material Properties on Ultra Precise Cutting Processes

Abstract In ultra precise cutting processes, the effect of work-material properties on the cutting force, cutting surface, etc. must be taken account in relation with its micro size of produced chips. This paper made it clear that the cutting mechanism became quite different either for polycrystal, single crystal and amorphous materials and for brittleness and ductileness. The specific cutting forces for several kinds of materials were experimentally obtained and discussed in view of “the size effect”. In the micro-cutting test of aluminum alloy with different grain size prepared by a special heat treatment, the cutting force varied several times at the grain boundary. Its effect on the surface finish was observed by optical microscope and it well coincided with the cutting force variation. The similar behavior could be investigated in the case of cutting germanium, however, the single crystal fluorite and amorphous acrylic resin gave more random or smooth cutting forces with rather regular and homogeneous surface properties.

Calculations of the effect of material anisotropy on microcutting processes

Abstract The depth of cut used in a microcutting process is comparable with the size of crystal grains; therefore, those polycrystal materials that could be regarded as homogeneous in conventional machining must be treated as heterogeneous. This article analyzes the relation between the crystallographic characteristics of a material with the microcutting process using the finite element method. The effects of crystal orientation and grain boundaries on the cutting process can be predicted, and the results were experimentally verified.

Development of Ultra Precision Machine Tool Made of Ceramics

Summary Most of the structural members of the developed machine consist of Alumina Ceramics, whose high specific rigidity and small coefficient of thermal expansion are expected to suit for ultra precise requirements. In addition, the ceramics are very easy to finish to a complete flatness by lapping operation. On the straight slideway obtained in this way, the slider must be traversed rigidly without any friction. For this purpose, a surface restricted type aerostatic slideway was adopted at the present design. The principle is that the air-restriction is given by narrow and very shallow grooves instead of annular oriffices. The characteristics of this type of bearing were solved by the help of computer and tested for several sliding models, and the one which was adopted is as follows; the clearance is 5 am, the rigidity is realized up to 200 N/am. The motion of machine should be as simple as possible, and only the linear motions are composed to a planer type machine tool, where X axis gives a cutting motion by a wire tension mechanism. Y axis presents a cross feed motion by laser feed back. friction drive mechanism, where two shafts cross each other, supported by aerostatic bearings at each end, and the rotational motion given by the servo motor to the one shaft is transformed to a linear motion to the other at the contact point. This system can afford positioning up to 0.08 μm. Z axis gives the tool engagement, where fine positioning is by a piezo-electric element. Here, the hysteresis loop is memorized in a computer and the response is linearized. This mechanism could realize a resolution of 0.03 μm. Some cutting tests were performed with a single crystal diamond tool. The test had shown the result of less than 0.05 μm of surface roughness.

Experiments on the effect of material properties on microcutting processes

Abstract The influence of workpiece material properties on microcutting processes were investigated in order to clarify the chip formation mechanism. Experiments were performed either with a constant depth of cut or a continuously increasing method with tool advance. The results obtained are as follows: (a) When the depth of cut is kept less than a micron, the material crystal structure affects the results. Polycrystal material must be treated as discrete and heterogeneous. Single crystal material is continuous and homogeneous, but anisotropic characteristics must be taken into consideration. (b) The behavior at the beginning of chip formation was influenced by the anisotropy, and the surface integrity varied with crystal orientation.

Frictional Properties of the Micro-Textured Surface of Anisotropically Etched Silicon

Abstract Anisotropic etching of silicon produces regular shapes that consist of {111} crystal planes. Applying a line-and-space mask pattern, textured surfaces with periodic regular shapes such as V-grooves are easily obtained. This paper first describes the design principle for such textures. By choosing an appropriate crystal orientation, symmetric or asymmetric grooves can be obtained. Variation of the texture profile is also discussed. The frictional properties are then examined. The effects of the texture were: (1) friction could be decreased, and (2) frictional directionality could be obtained with a combination of asymmetric texture and softer materials.

An Analysis of Surface Properties of Hetero-Epitaxially Grown SiC Surface on Si Substrate

Abstract The molecular beam epitaxy process can produce single crystal and smooth surface at atomic level as well as synthesizing the desired material by supplying the multiple materials on substrates. This paper deals with an application of the hetero-epitaxial process of silicon carbide (SiC) on silicon (Si) substrate, and aims to make clear the attainable surface roughness and its properties. It was found that the steep pits were formed during the carbonization process before the epitaxy and that they strongly affected the final roughness. The attainable roughness was 0.4nm rms. Finally, the applicability to toroidal mirror optics was discussed.

Functional Texture Design and Texturing Processes

Int. J. of Automation Technology submitted 1 Abstract. Various functions can be obtained by applying regular patterns or texture on a surface. Depending on the functions, required dimension of the texture, e.g. pitch, varies in wide range from nanometers for optical function to millimeters for friction. In addition, high aspect ratio of the cross sectional profile or hierarchical structure of micro/nano-structure is required for example to control the wettability. This paper reviews various processes for functionalities including their applications.

Selective Cell-Adhesion on Micro-Structured Fine Particles

The present paper describes spatially selective adhesion of rat phenochromocytoma (PC12) cells on micro-structured fine particles. The particles are packed hexagonally in two-dimensional arrangements by self-assembly. Incubation allows most cells to be successfully adhered to the region of self-assembled particles, while few cells are found on the rest of the glass substrate. The line-and-space structure of particles aligns the cells in straight lines. The desired location of cells can be obtained for both appropriate line width and space of particles, because they dominate a spatial selectivity of cell adhesion.

Fabrication of Spatially-Patterned Cells Using Selective Adhesion on Pre-Structured Fine Particles

The application of a neuron network to a bio/micro-sensor has potential as a drug screening device. In this study, micro-structures of surface-modified particles were applied to a scaffold for selective cell adhesion and growth. Silica particles were covered with a specific protein (fibronectin) or multi-walled carbon nanotubes (CNT) by electrostatic adsorption or transfer printing, respectively. They formed spatial patterns in a line-and-space structure tens of micrometers wide on a glass substrate. This paper investigates the effect of the coated material on the selectivity and adhesiveness of PC12 phenochromocytoma cells. An incubation process causes PC12 cells to autonomously align with selective adhesion on the micro-structures of both particles. The cells are minimally adhered to the glass surface around the particles. The structure of the fibronectin-coated particles enables a straight and uniform alignment of adhered cells, while that of bare silica particles causes randomly distributed cells. It was also found that the structure of CNT-adsorbed particles enhances cell adhesiveness to grow pseudopods of adhered cells.

Microlinear Motion Bearing Produced by Anisotropic Etching of Silicon

Abstract This paper demonstrates the applicability of silicon anisotropic etching to the production of linear motion bearing. Machining accuracy of this etching depends not on the copying rule but the crystal regularity. As a result, accurate shapes such as V-grooves can be machined without precise control. The etched V-grooves are applied to the linear bearing system whose slider size is of the order of sub-millimeters and its stroke is about 3mm. First, the geometrical accuracy is evaluated. Then, the slider is driven by an actuator and the frictional force was measured. The coefficient of friction exceeds 3 in this case. Finally, the possibility of larger scale and more precise application is discussed.