• Design & Manufacturing
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• 제10권3호
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• pp.8-13
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• 2016

Despite technological advance, there have been several troubles in photo reaction injection molding (photo RIM) to produce ultra thin light guide panels (LGPs). In this study, micro leakage problem at cavity edge during photo RIM was investigated numerically. In order to obtain optimal processing conditions, we regulated inlet pressure of injected resin at the cavity edge and figured out micro leakage behaviors. At low inlet pressure (less than 100 Pa), though the micro leakage problem was not occurred, another problem, short shot due to not enough driving force, was appeared More than 1,000 Pa of the inlet pressure, injected resin was rapidly leaked through the micro gap at the cavity edge. Finally, we obtained optimal inlet pressure around 600 ~ 1,000 Pa. At this region, injected resin fully filled the cavity without micro leakage behavior. Based on the present study, further comparative investigations with experimental photo RIM should be performed to find optimal processing conditions for produce ultra thin LGPs.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2005년도 춘계학술대회 논문집
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• pp.317-320
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• 2005

The micro-alloying forging steels have been developed to save energy consumption during forging and subsequent heat treatment stages. The work hardening ability of micro-alloying forging steels is one of major hardening component while it gives severe die damage if the forging process design is poorly set up on the other hand. In the present study, it was tried to characterize three types of micro-alloying forging steels to understand the differences with the conventional low carbon steels used fur cold forging with a spherodizing heat treatment. After forging of a certain forging part with both micro-alloying forging steels and conventional low carbon steel, several mechanical tests were carried out.

• 한국공작기계학회논문집
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• 제16권6호
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• pp.193-200
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• 2007

Micro forming is a suited technology to manufacture very small metallic parts(several $mm{\sim}{\mu}m$). Al5083 superplastic alloy with very small grains has a great advantage in achieving micro deformation under low stress due to its relatively low strength at a specific high temperature range. Micro forming of $Zr_{62}Cu_{17}Ni_{13}Al_8$ bulk Metallic glass(BMG) as a candidate material for this developing process are feasible at a relatively low stress in the supercooled liquid state without any crystallization during hot deformation. In this study, the micro formability of Al5083 superplastic alloy and bulk metallic glass, $Zr_{62}Cu_{17}Ni_{13}Al_8$, was investigated with the specially designed micro vibration forming system using pyramid-shape, V-shape and U-shape micro die pattern. With these dies, micro vibration forming was conducted by varying the applied load, time. Micro formability was estimated by comparing the hight of formed shape using non-contact surface profiler system. The vibration load effect to metal flow in the micro die and improve the micro formability of Al5083 superplastic alloy and $Zr_{62}Cu_{17}Ni_{13}Al_8$ bulk Metallic glass(BMG).

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2003년도 춘계학술대회 논문집
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• pp.636-639
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• 2003

It is difficult to machine below 10 micrometers by conventional machining methods, such as micro-EDM. However, ultra micro machining using focused ion beam(FIB) is able to machine to 50 nanometers. In addition, 3 dimensional structures can be made by a combination of FIB and CVD to the level of 10 nanometers. Die ＆ moulds techniques are better than one-to-one machining techniques in the mass production of ultra size structures, in regards to production costs. In this case, the machining precision of die ＆ moulds affects produced parts. Also, it is advantageous to machine die ＆ moulds to the 10 micrometer level by FIB technique rather than other techniques. In this paper, the grooving characteristics for die ＆ mould materials by FIB were carried out experimentally in order to compare the machining characteristics of FIB with conventional machining methods. The results showed that the machining parameters and the scanning path of FIB affects the precision. The machined width and depth of the groove varied depending on the required depth due to the redeposition of the sputtered ion material accumulating on both the bottom and the side of the wall.

• Design & Manufacturing
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• 제2권5호
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• pp.43-47
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• 2008

Micro Electrochemical Machining(Micro ECM) has traditionally been used in highly specialized fields such as those of the aerospace and defense industries. It is now increasingly being applied in other industries where parts with difficult-to-cut material, complex geometry and tribology such as compute. hard disk drive(HDD) are required. Pulse Electrochemical Micro-machining provides an economical and effective method for machining high strength, high tension, heat-resistant materials into complex shapes such as turbine blades of titanium and aluminum alloys. Usually aluminum alloys are used bearings to hard disk drive in computer. In order to apply aluminum alloys to bearing used in hard disk drive, this paper presents the characteristics of Micro ECM for aluminum alloy.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2001년도 춘계학술대회 논문집
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• pp.1080-1084
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• 2001

In manufacturing a micro die with half spherical cavity by MEDM, it is necessary to prepare an electrode with the same shape. This paper suggests a simple method to manufacture a half spherical electrode based on tool wear. The tool wears more rapidly at the edge of a cylindrical electrode. In order to make a half spherical micro electrode, cylindrical electrode was fed into the workpiece by the distance of its radius. The d/R(depth/Radius) value varied with respect to capacitance and electrode diameter. The smaller the size of electrode was, the closer the electrode tip geometry approached to a half sphere.

• Design & Manufacturing
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• 제10권3호
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• pp.25-29
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• 2016

Recently, a hyaluronic acid micro needle patch for therapeutic and cosmetic purposes has been used by attaching directly to the skin with a pattern having a micro needle shape of 1/3 thickness of hair. These products are attracting attention as an innovative product that maximizes the effect by activating the active ingredient in the skin in the deep skin without blocking the horny layer because the micro needle shape exists on the patch surface so that it can penetrate effectively to the skin. Currently, DAB (droplet air blowing) or MEMS technology is used to make pattern shapes for patches. Because of this technology, manufacturing time is long and manufacturing cost is high, so we tried to develop the mold technology to machine the microneedle shape directly to the metal. In this study, we first fabricated a needle pattern with a quadrangular pyramid shape and finally produced a conical needle pattern.

• Design & Manufacturing
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• 제12권1호
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• pp.47-51
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• 2018

As the IT industry rapidly progresses, the functions of electronic devices and display devices are integrated with high density, and the model is changed in a short period of time. To implement the integration technology, a uniform micro-pattern implementation technique to drive and control the product is required. The most important technology for the micro pattern generation is the exposure processing technology. Failure to implement the basic pattern in this process cannot satisfy the demands in the manufacturing field. In addition, the conventional exposure method of the mask method cannot cope with the small-scale production of various types of products, and it is not possible to implement a micro-pattern, so an alternative technology must be secured. In this study, the technology to implement the required micro-pattern in semiconductor processing is presented through the photolithography process and plasma etching.

• 소성∙가공
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• 제9권5호
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• pp.533-538
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• 2000

This study has been carried out to develop a CRT die using hot forging. The conventional CRT die made by casting has defects such as void and inclusion. These defects of the cast die make micro-spots on the surface of the CRT which affect the quality of the final product. So, a hot forging process is developed to avoid these defects of CRT die by the model material test and the rigid-plastic FEM. Firstly, model material tests are carried out with plasticine billets in order to investigate the material flow pattern in the die cavity and to get the reasonable initial values for designing the preform in the FE simulation. And then a finite element analysis has been performed to Predict the preform and the forging load of a CRT die. We also suggest an integrated die-set which combines two die-sets into one die-set to save manufacturing time and cost in case of similar die-size.

• 반도체디스플레이기술학회지
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• 제18권2호
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• pp.6-10
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• 2019

In the presence of $\mu-tip$ for narrow stripe coating, there appears lateral capillary flow along the hydrophilic head lip because the $\mu-tip$ has some resistance to flow. It was known to be suppressed by increasing the contact angle of the head lip. In this paper, we have demonstrated by computational fluid dynamics(CFD) simulations that it can also be suppressed by the formation of micro-patterns on the shim and meniscus guide embedded into the slot-die head. To optimize the micro-patterned structure, we have performed simulations by varying the groove width, depth, and clearance. In the absence of micro-patterns, it is shown by experiment and simulation that the solution spreads to a distance of $1,300{\mu}m$ from the ${\mu}-tip$. In the presence of micro-patterns with the groove width and clearance of $50{\mu}m$, the distance the solution spreads is reduced to $260{\mu}m$. However, no further suppression in the capillary flow is observed with micro-patterns with the groove width of $40{\mu}m$ or less. It is also observed that the capillary flow is not affected by the groove depth if it is larger than $10{\mu}m$. We have shown that the distance the solution spreads can be reduced further to $204{\mu}m$ by coating a hydrophobic material (contact angle of $104^{\circ}$) on the surface of micro-patterns having the groove width and clearance of $50{\mu}m$.