• Journal of the Korean Society for Precision Engineering
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• v.18 no.7
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• pp.65-71
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• 2001

The development process of the polishing system for the aspherical lens mold for opto-electronics industry is described. The system uses the method that polishing tool is scanned on the surface under PC-NC control for the aspherical lens mold. The two axes interpolation of the minimum translation mechanism is applied to give uniform working condition by motion analysis. An aspherical surface is divided into multiple sections and each dwell time is calculated from the polishing rate model based on the Preston equation. As result of form error compensation experiment, initial form error is decreased about 25% while an average value of surface roughness is also reduced successfully from 180nm to 19nm.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.9 no.2
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• pp.26-32
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• 2010

This paper reports some experimental result in grinding and polishing of silicon cathodes used in semiconductor manufacturing process. Cup shape diamond core wheels were used in experiments and the radial and tangential grinding forces were measured with surface roughness. In polishing experiments, flat type and donut type wool polishing tools were tested. The experimental results indicate that the grinding forces are proportional to the material removal rates and the surface roughness are inversely proportional to the spindle speed. The surface roughness of polished Si decreases with polishing time and higher spindle speed.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.19 no.5
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• pp.616-621
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• 2010

New type of the base material of the light-emitting diode requires copper wafer in view of heat and electrical conductance. Therefore, polishing process of the substrate level is needed to get a nanometer level of surface roughness as compared with pattern structure of nano-size in the semiconductor industry. In this paper, a series of lapping and polishing technique is shown for the rough and deflected copper substrate of thickness 3mm. Lapping by sand papers tried air cooling method. And two steps of polishing used the diamond abrasives and the $Al_2O_3$ slurry of size 100mm considering the residual scratch. White-light interferometer proved successfully a mirror-like surface roughness of Ra 6nm on the area of $0.56mm{\times}0.42mm$.

• Transactions on Electrical and Electronic Materials
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• v.6 no.3
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• pp.128-132
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• 2005

In this paper, we have investigated the characteristics of the magnetic abrasive using sludge on polishing of internal finishing of seamless stainless steel (STS304) tube applying magnetic abrasive polishing. Either white alumina (WA) or green carborundum (GC) grain was used to resin sludge at a low temperature, and the sludge of magnetic abrasive powder was synthesized and crushed into 200 meshes. Surface roughness was measured before and after polishing, and more than $40\%$ of improvement of surface roughness was achieved when WA grain was used under a specific condition. Even though some degree of surface roughness due to deeper scratches still exist, but the result showed a prospective magnetic abrasive polishing using sludge with WA or GC grains.

• Journal of the korean academy of Pediatric Dentistry
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• v.43 no.3
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• pp.275-283
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• 2016

The aim of this study was to evaluate the surface characteristics of composite resins polished with two different polishing methods. 30 disk-shaped specimens were prepared with microhybrid (Filtek$^{TM}$ Z250) and nanofilled (Filtek$^{TM}$ Z350) resins respectively, and classified into three groups: not polished as controls, polished by an abrasive disk (Soflex), and polished by a polishing brush (Occlubrush). Surface roughness was increased after polishing. In terms of micro-roughness, there were no significant differences between the two polishing methods. But macro-roughness values were markedly increased in the Occlubrush group (p < 0.05). In the Sof-lex group, the matrix and fillers were polished together, resulting into a smoother and homogeneous surface. However, in the Occlubrush group, the matrix layer was torn off, with more heterogeneous surfaces and large scratches. In regards to micro-hardness, no significant differences were observed between the two polishing systems (p > 0.05). And the hardness value increased about 25% after polishing. In conclusion, the method of polishing should be chosen deliberately in view of the hardness characteristics of composite resins. Sof-lex is recommended to improve the surface characteristics of polished resins.

• Tribology and Lubricants
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• v.38 no.5
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• pp.222-226
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• 2022

Between diaphragms made of stainless steel (SUS), which is the main component of a hydrogen gas compressor, micro-slip occurs owing to repeated bending, resulting in scratches on the surface. The surface scratch of the compressor part is a problem with airtightness, which reduces the efficiency of the compressor; in severe cases, damage is a possibility. In this study, the changes in friction and wear characteristics due to the surface polishing of SUS and carbon-based solid lubricant films (graphene and CNT) were analyzed. Bare SUS, polished SUS, graphene film, and CNT film specimens were prepared. The surface roughness of the SUS was significantly reduced by surface polishing but increased by carbon-based solid lubricating films. In contrast, the friction coefficient maintained a similar value after surface polishing but was significantly reduced by the carbon-based solid lubricant films. In particular, the graphene film exhibited the lowest initial friction coefficient, while the CNT film exhibited the lowest overall average friction coefficient. Regarding the wear rate, polished SUS exhibited the lowest value, but the surface condition of the wear track showed that the carbon-based solid lubricating films were relatively less damaged. Although the wear rate measured was largely attributed to the solid lubricating film peeling off, the SUS surface under the film was considered protected.

• Design & Manufacturing
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• v.13 no.3
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• pp.12-18
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• 2019

Fluid jet polishing is a method of jetting a fluid to polish a concave or free-form surface. However, the fluid jet method is difficult to form a stable polishing spot because of the lack of concentration. In order to solve this problem, MR fluid jet polishing system using an abrasive mixed with an MR fluid whose viscosity changes according to the intensity of a magnetic field is under study. MR fluid jet polishing is not easy to formulate for precise optimal conditions and material removal due to numerous fluid compositions and process conditions. Therefore, in this paper, quantitative data on the factors that have significant influence on the machining conditions are presented using various simulations and the correlation studies are conducted. In order to verify applicability of the fabricated MR fluid jet polishing system by nozzle diameter, the flow pattern and velocity distribution of MR fluid and polishing slurry of MR fluid jet polishing were analyzed by flow analysis and shear stress due to magnetic field changes was analyzed. The MR fluid of the MR fluid jet polishing and the flow pattern and velocity distribution of the polishing slurry were analyzed according to the nozzle diameter and the effects of nozzle diameter on the polishing effect were discussed. The analysis showed that the maximum shear stress was 0.45 mm at the diameter of 0.5 mm, 0.73 mm at 1.0 mm, and 1.24 mm at 1.5 mm. The cross-sectional shape is symmetrical and smooth W-shape is generated, which is consistent with typical fluid spray polishing result. Therefore, it was confirmed that the high-quality surface polishing process can be stably performed using the developed system.

• Journal of the korean academy of Pediatric Dentistry
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• v.51 no.3
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• pp.197-207
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• 2024

This study aims to evaluate the color stability and surface roughness of the single-shade composite resin after finishing and polishing for primary molars. A single-shade composite resin (OM, OMNICHROMA) and two multi-shade composite resins (FT, Filtek^TM Z350XT; ES, ESTELITE^® SIGMA QUICK) were included. The specimens were divided into three subgroups using different polishing methods: control, Sof-Lex XT, and Sof-Lex Diamond. For color stability tests, cavities were prepared on extracted primary second molars and restored with experimental composite resins. Each specimen was immersed in the coffee solution for 48 hours. The color difference of each specimen was calculated. For surface roughness tests, cylindrical specimens were crafted with experimental composite resins. Surface roughness was analyzed using an atomic force microscope and a scanning electron microscope. In the color stability tests, FT demonstrated a significantly lower ΔE_ab than ES among the control groups, but no significant differences were observed between the ΔE_ab values of OM and FT or OM and ES. Additionally, no significant differences were found between the Sof-Lex XT and Sof-Lex Diamond subgroups in the three composite groups. Moreover, no significant differences in the surface roughness were found between the three composite groups, regardless of the polishing methods. The single-shade composite resin demonstrated comparable color stability and surface roughness to that of the multi-shade composite resins regardless of the polishing methods used in restoring primary molars. The single-shade composite resin is expected to be applicable in clinical pediatric dentistry reducing chair time due to the easy shade matching procedures.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.35 no.12
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• pp.1641-1646
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• 2011

The second-generation magnetic abrasive polishing is one of the nontraditional machining technologies newly developed. Because of the flexibility effect in magnetic abrasive polishing, the precise and mirror like surface can be obtained during this process. In this study, magnetic abrasive polishing process was applied in small grooved surface. As a result, it was seen that the flexible magnetic abrasive tool was effective to remove burrs on the edge of the groove. However, the efficiency of magnetic abrasive polishing at the slot was very low according to increasing depth and width of slot. So, correlation between geometric parameters, such as the depth and width, and surface roughness was evaluated and the minimum width for suitable polishing was found by experimental results.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 1998.03a
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• pp.59-64
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• 1998

We need to achieve th mass product through methods of higher efficient, higher precise manufacturing process than those of existing precision abrasive machining. Thus, this study is to develop mirror-like surface machining technique of outer diameter of the piston pin by the compound magneto-electrolytic abrasive polishing system. The procedure of machining is followed as first, fulfill the pre-processing by cylindrical grinder, second, complete mirror-like surface by the method of magneto-electrolytic abrasive polishing used CBN non-woven abrasive pads. In this study, it was found that the best suitable conditions of mirror-like surface polishing were that the electrode density was 0.1A/$\textrm{cm}^2$, the applied pressure 1.5kgf/$\textrm{cm}^2$, the feed rate 0.5mm/rev, and the rotoation velocity of workpiece 80rpm, and that the surface roughness was reduced in this conditions.