The demand fer small and high-capacity optical data storage devices has rapidly increased. The areal density of optical disk is increased by using higher numerical aperture objective lens and shorter wavelength source. A wafer-scale stacked micro objective lens with a numerical aperture of 0.85 and a focal length of 0.467mm for the 405nm blue- violet laser was designed and fabricated. A diffractive optical element (DOE) was used to compensate the spherical aberration of the objective lens. Among the various fabrication methods for micro DOE, the UV-replication process is more suitable fur mass-production. In this study, an 8-stepped DOE pattern as a master was fabricated by photolithography and reactive ion etching process. A flexible mold was fabricated for improving the releasing properties and shape accuracy in UV-replication process. In the replication process, the effects of exposing time and applied pressure on the replication quality were analyzed. Finally, the surface profiles of master, mold and molded pattern were measured by optical scanning profiler. The geometrical deviation between the master and the molded DOE was less than $0.1{\mu}m$. The diffraction efficiency of the molded DOE was measured by DOE efficiency measurement system which consists of laser source, sample holder, aperture and optical power meter, and the measured value was $84.5\%$.

In the present research, the simultaneous punching of ultra small size hole of $2\~10\;{\mu}m$ in diameter on flat rolled thin metal foils was conducted with elastic polymer punch. Workpiece used in the present investigation were the rolled pure copper of $3{\mu}m$ in thickness and CP titanium of 1.5fm in thickness. The metal foils were punched with the dies and arrays of circular and rectangular holes were made. The process set-up is similar to that of the flexible rubber pad farming or Guerin process. Arrays of holes were punched successfully in one step forming. The punched holes were examined in terms of their dimensions. The effects of the wafer die hole dimension and heat treatment of the workpiece on ultra small size hole formation of the thin foil were discussed. The process condition such as proper die shape, pressure, pressure rate and diameter-thickness ratio (d/t) were also discussed. The results in this paper show that the present method can be successfully applied to the fabrication of ultra small size hole away in a one step operation.

The rapid thermal response (RTR) molding is a novel process developed to raise the temperature of mold surface rapidly to the polymer melt temperature prior to the injection stage and then cool rapidly to the ejection temperature. The resulting filling process is achieved inside a hot mold cavity by prohibiting formation of frozen layer so as to enable thin wall injection molding without filling difficulty. The present work covers flow simulation of thin wall injection molding using the RTR molding process. In order to take into account the effects of thermal boundary conditions of the RTR mold, coupled analysis with transient heat transfer simulation is suggested and compared with conventional isothermal analysis. The proposed coupled simulation approach based on solid elements provides reliable thin wall flow estimation for both the conventional molding and the RTR molding processes.

A optical head unit for nano optical probe array was developed. The optical probe array is generated by Talbot effect. The shape and thickness of microlens array(MLA) were designed to minimize the spot size at the foci of MLA. To increase the optical efficiency of the system and obtain the large tolerance for fabrication, aperture size was theoretically optimized. Then microlens illuminated aperture array(MLIAA) as an optical head unit was fabricated using a ultra violet(UV) molding process on aluminum aperture array. In this process, Al aperture array was fabricated separately using the photolithography and reactive ion etching(RIE) process. Optical properties of the generated optical probes were measured and compared at Talbot distance from the aperture array having a diameter of $1{\mu}m$ and MLIAA.

It is necessary to improve the pattern replication and birefringence in LGP(Light guide panel) for better optical performance. In the present paper, the effects of injection-compression and injection-press mode with normal injection mold on the distribution of transcription of pattern and birefringence were studied. It was found that the values of pattern replication was improved and the birefringence was reduced for the cases of low initial clamping force in injection-compression mode and for the cases of longer mold opening length in injection-press mode, repectively.

Microlens arrays were fabricated by a modified LIGA process composed of the exposure of a PMMA (Polymethylmethacrylate) sheet to deep x-rays and subsequent thermal treatment. A successful modeling and analyses for microlens formation were presented according to the experimental procedure. A nickel mold insert was fabricated by the nickel electroforming process on the PMMA microlens arrays fabricated by the modified LIGA process. For the replication of microlens arrays having various diameters with different foci on the same substrate, both hot embossing and microinjection molding processes have been successfully utilized with the fabricated mold insert. Replicated microlenses showed very good surface roughness with the order of 1 nm. The focal lengths of the injection molded microlenses were successfully estimated theoretically and also measured experimentally.

For mass production, usually injection mold has multi-cavity which is filled through geometrical balanced runner system. Despite geometrical balanced runner system, filling imbalances between cavity to cavity have always been observed. These filling imbalances are one of the most significant factors to affect quality of plastic parts. Filling imbalances are results from non-symmetrical shear rate distribution within melt when it flows through tile runner system. It has been possible to decrease filling imbalance by optimizing processing conditions, but it has not completely eliminated this phenomenon during injection molding processing. This paper presents a solution for these filling imbalances by using Runner Core pin (RC pin). The Runner Core pin which is developed in this study creates a symmetrical shear distribution within runner. As a result of using Runner Core pin, a remarkable improvement in reducing filling imbalances was confirmed.

It is well known that the family-mold has an advantage to reduce the cost for production and mold. However, defects are frequently occurred by over packing the smaller volume cavity during molding, especially when the family-mold has a volumetric difference between two cavities. In this study, the cavity-filling imbalance was confirmed by the temperature and the pressure sensors, and a variable-runner system was developed for balancing the cavity-filling. Experiments of balancing the cavity filling was carried out in the family-mold with the variable-runner system, and balancing the cavity-filling was confirmed by changing the cross-sectional area of a runner in the variable-runner system with the temperature and pressure sensors. The influence of the injection speed to the balancing-capability of the variable-runner system was also examined in the experiment.

High speed milling experiment on the hardened mold steel (CALMAX at hardness of HRC 55) is carried out using small diameter ball endmills. Tool lift and wear characteristics under the various machining parameters are investigated Effect of dynamic runout on the wear of the tool is also studied. For most of the cases, catastrophic chipping of tool edge is not observed and uniformly distributed wear on the flank surface of the tool is obtained. It is found that lower rate of tool wear is obtained as the cutting speed is increased. Also, high pick feed rate is found to be more favorable in terms of the tool wear and material removal rate.

In recent industry, with the miniaturization and high-precision of machine part, the development of mold manufacturing technology for mass production is accompanied by the development of new technology such as IT and BT In this study, the spiral type injection mold with a $200{\mu}m$ thickness is made to. investigating the influence of injection molding parameter and the flow length is measured through an experiment. Besides, Taguchi method is used in this experiment and the obtained data are analyzed using ANOVA method.

In recent, various shapes of pattern in micron or nano scale are adapted in many applications due to their good mechanical or optical properties. Light guide panel (LGP) of the LCD is one of important applications for micro pattern and micro prism shape is one of the typical patterns. The size of the surface patterns in most applications is decreasing to the order of micron or even under micron. On the other hand, the area to be patterned keeps enlarging. These two trends in patterned products require tooling micro patterns on large surface, which has still many technical problems to be solved mainly due to pattern size and the tooling area. In this study, we fabricated prism shape of patterns using diamond cutting tool on some metal core and plastic core like PMMA. Some cutting conditions were investigated including cutting force, cutting depth and speed for different core materials.

In this study, warpage characteristics of mobile phone cover through injection molding process were investigated using design of experiments in injection molding process. Warpage in plastic injection molding has a significant effect on quality of product. Effects of injection time, packing pressure, packing time, mold temperature and melt temperature on the warpage of mobile phone cover were considered by numerical analysis and experiment with Taguchi method. The degree of warpage for the injection molded part was measured by using three dimensional coordinate measurement machine. It was shown that temperature control factor has more significant effect on the warpage of mobile phone cover than pressure control factor.

In this paper, the web-based monitoring system is developed for the effective process monitoring of mold manufacturing using web. In developed system, the cutting force for monitoring the manufacturing condition is measured using hall-sensor that is low cost and useful to be installed in a machine tool indirectly. Specially, the current of main spindle in a machine tool is converted into cutting force by various experiments. For effective web-based monitoring, the program which runs in the local computer of client is made to exchange message between a server and a client by making of ActiveX control and the result of manufacturing is shown on web-browser by Ch language. The developed system in this study is the foundation of establishing E-manufacturing in mold factory.