The objective of this work is to suggest a maskless pattern fabrication technique using the combination of machining by Nanoindenter® XP and HF wet etching. Sample line patterns were machined on a borosilicate surface by constant load scratch (CLS) of the Nanoindenter® XP with a Berkovich diamond tip, and they were etched in HF solution to investigate chemical characteristics of the machined borosilicate surface. All morphological data of scratch traces were scanned using atomic force microscope (AFM).

Laser-induced thermochemical wet etching of titanium in phosphoric acid has been investigated to examine the feasibility of this method for fabrication of microstructures. Cutting, drilling, and milling of titanium foil were carried out while examining the influence of process parameters on etch width, etch depth, and edge straightness. Laser power, scanning speed of workpiece, and etchant concentration were chosen as major process parameters influencing on temperature distribution and reaction rate. Etch width increased almost linearly with laser power showing little dependence on scanning speed while etch depth showed wide variation with both laser power and scanning speed. A well-defined etch profile with good surface quality was obtained at high concentration condition. Fabrication of a hole, micro cantilever beam, and rectangular slot with dimension of less than 100㎛ has been demonstrated.

In mold machining, there are many concave machining regions where chatter and tool deflection occur since MRR (material removal rate) increases as curvature increases even though cutting speed and depth of cut are constant. Boolean operation between stock and tool model is widely used to compute MRR in NC milling simulation. In finish cutting, the side step is reduced to about 0.3㎜ and tool path length is sometimes over 300m, so Boolean operation takes long computation time and includes much error if the resolution of stock and tool model is larger than the side step. In this paper, curvature of CL (cutter location) surface and side step of tool path is used to compute the feedrate for constant MRR machining. The data structure of CL surface is Z-map generated from NC tool path. The algorithm to get local curvature from discrete data was developed and applied to compute local curvature of CL surface. The side step of tool path was computed by point density map which includes cutter location point density at each grid element. The feedrate computed from curvature and side step is inserted to new tool path to regulate MRR. The resultants were applied to feedrate optimization system which generates new tool path with feedrate from NC codes for finish cutting. The system was applied to the machining of speaker and cellular phone mold. The finishing time was reduced to 12.6%, tool wear was reduced from 2㎜ to 1.1㎜ and chatter marks and over cut on corner were reduced, compared to the machining by constant feedrate. The machining time was shorter to 17% and surface quality and tool was also better than the conventional federate regulation using curvature of the tool path.

Ceramics are very difficult-to-cut materials because of its high strength and hardness. Their machining mechanism is characterized by cracking and brittle fracture. In this paper, to give good machinability to the ceramics, h-BN powders are added to Si₃N₄ by volume of 20, 25 and 30%. And the machinability of the produced ceramics is tested using micro drilling system. Through required experimental works, it is shown that the micro drilling machinability is varied along with the volumetric percentage of h-BN powders. Also, it is verified that the obtained results can be used to develop new machinable ceramics of good material properties and machinability.

This paper describes a method for digitizing the compound surfaces which are comprised of several unknown feature shapes such as base surface, and draft wall. From the reverse engineering's point of view, the main step is to digitize or gather three-dimensional points on an object rapidly and precisely. As wen known, the non-contact digitizing apparatus using a laser or structured light can rapidly obtain a great bulk of digitized points, while the touch or scanning probe gives higher accuracy by directly contacting its stylus onto the part surface. By combining those two methods, unknown features can be digitized efficiently. The paper proposes a digitizing methodology using the approximated surface model obtained from laser-scanned data, followed by the use of a scanning probe. Each surface boundary curve and the confining area is investigated to select the most suitable digitizing path topology, which is similar to generating NC tool-paths. The methodology was tested with a simple physical model whose shape is comprised of a base surface, draft walls and cavity volumes.

The growing need for higher precision and productivity in manufacturing industry has lead to an increased interest in computer numerical control (CNC) systems. It is well known fact that the cross-coupling controller (CCC) is an effective method for contouring applications. In this paper, a multi-axis contour error controller (CEC) based on a contour error vector using parametric curve interpolator is introduced. The contour error vector is a vector from the actual tool position to the nearest point on the desired path. The contour error vector is the closest error model to the contour error. The simulation results show that the CEC is more accurate than the conventional CCC for a biaxial motion system. In addition, the experimental results on 3-axis motion system show that the CEC is simply applied to 3-axis motions and contouring accuracy is significantly improved.

In this paper, a development of an inductive position sensor is described. The sensor is similar to a radial magnetic bearing in that the sensor stator is shaped like a heteropolar magnetic bearing and is driven by a switching amplifier. A demodulation filter extracts the gap information from the switching current ripples. A prototype sensor exhibits the resolution of 0.43㎛ and the dynamic bandwidth of about 800Hz. The dynamic performance can be improved by increasing the switching frequency. However, the eddy current effects become noticeable at high switching frequency, thus limiting the improvement of the bandwidth.

The light pattern reflected from a machined surface contains some information like roughness and profile on the projected surface as expected in the Beckmann-Spizzichino model. In applying the theory into a real reliable measuring device, many parameters such as incident light power, wave length, spot size shoud be kept a constant optical value. However, the reflected light power is likely to change with the environmental noise, the variations of the light source, the reflectivity of the surface, etc. even though the incident light power is constant. In this study, a method for adjusting the incident light power to keep the reflected light power projected on a CMOS image sensor constant was proposed and a simple adjustment algorithm based on PI digital control was examined. Experiments verified that the proposed method made the surface roughness measurement better and more reliable even under variations of the height of light source.

Recently, vehicle simulators are widely used to evaluate driver's responses and driver assistance systems. It needs much effort to construct the virtual driving environment for a vehicle simulator. In this study, it is described how to make effectively the roads and the driving environment for a vehicle simulator. The GIS (Geographic Information System) is used to construct the roads and the environment effectively. Because the GIS is the integrated system of geographical data, it contains useful data to make virtual driving environment. First, the outline and centerline of roads is abstracted from the GIS. From the road outline, the road width is calculated. Using the centerline, the grid model of roads is constructed. The final graphic model of roads is constructed by mapping road image to the grid model according to the number of lanes and the kind of surface. Data of buildings from the GIS are abstracted. Each shape and height of buildings is determined according to kind of buildings, the final graphic model of buildings is constructed. Then, the graphic model of roadside tree is also constructed. Finally, the driving environment for driving simulator is constructed by converting the three graphic models with the graphic format of Direct-X and by joining the three graphic models.

It is necessary to improve the exactness and adaptation of the working environment in the intelligent robot system. The vision sensor have been studied for this reason for a long time. However, it is very difficult to perform the camera and robot calibrations because the three dimensional reconstruction and many processes are required for the real usages. This paper suggests the image based visual servoing to solve the problem of old calibration technique and supports OLP(Off-Line-Programming) path compensation. Virtual camera can be modeled from the real factors and virtual images obtained from virtual camera gives more easy perception process. Also, Initial path generated from OLP could be compensated by the pixel level acquired from the real and virtual, respectively. Consequently, the proposed visually assisted OLP teaching remove the calibration and reconstruction process in real working space. With a virtual simulation, the better performance is observed and the robot path error is calibrated by the image differences.

Carbon fiber reinforced composites(CFRP) were fabricated with phenolic resin matrix by hot press molding, and its surface was modified by the ion-assisted reaction process. When we tested the friction coefficient and wear rate variation and observed the effect of fibers with respect to friction and wear characteristics, the amount of pitch based carbon fiber was 45wt% and the average friction coefficient was the lowest at 0.12. When the amount of ion-irradiation was 1×10¹? ions/㎠, the friction coefficient of the composites was about 0.12 and the wear mode was stable, whereas, the friction coefficient of the non-treated composites was about 0.16 and the wear mode was very unstable. But if the amount of ion-irradiation was 5×10¹? ions/㎠, the friction coefficients were higher compared to that of 1×10¹? ions/㎠ ion-irradiation case.

Rapid prototyping (RP) technologies have been widely used to reduce the lead-time and development cost of new products. VLM-_ST process has been developed to overcome the currently developed RP technologies such as a large building time, a high building cost, an additional post-processing and a large apparatus cost.
VLM-_ST process requires an additional human interaction due to the manual stacking and bonding. Hence, building time, building cost and the part quality are dependent on the skill of labor. A novel RP process, fully automated VLM-_STprocess (VLM-(VLM-_STA), has been developed to improve building efficiency of the process and the human dependency of the part. The objective of this work is to propose a VLM-(VLM-_STA process and to develop an apparatus for implementation of the process. VLM-(VLM-_STA process and its apparatus have various technical novelties such as two step cutting using a rotating table, an automatic stacking method using two pilot holes and two reference shapes, a concept of automatic unit shape layer (AUSL), and an automatic bonding using the bonding roller and building magazine.
In order to examine the efficiency and the applicability of the proposed process, various three-dimensional shapes, such as a piston, a human head shape and a human bust shape, were fabricated on the apparatus.