• Journal of the Korean Society for Precision Engineering
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• v.29 no.3
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• pp.266-272
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• 2012

This paper has aims to share fundamental knowledge for magnetic abrasive polishing and to mainly introduce recent research results. In order to enhance a magnetic flux density for nonferrous materials, advanced magnetic abrasive polishing system which is called 2nd generation system was established by electro-magnet array table, and the effectiveness of the electromagnet array table was evaluated in real polishing experiments. To increase adhesiveness of the abrasives in high speed polishing, a silicone gel agent was proposed and carbon nanotube particles as new magnetic abrasives were applied in the magnetic abrasive polishing. In addition, a strategy for optimal step-over determination by heuristic algorithm was introduced for applying large size workpiece. Curved surfaces having a uniform radius were simulated and tested with installed electro-magnet array table.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.51 no.7
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• pp.311-315
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• 2002

Chemical mechanical polishing (CMP) process was required for the global planarization of inter-metal dielectric(IMD), inter-level dielectric (ILD) layers of multi-layer interconnections. In this paper, we studied the characteristics of polishing pad, which can apply shallow trench isolation (STI)-CMP process for global planarization of multi-level interconnection structure. Also, we investigated the effects of different sets of polishing pad, such as soft and hard pad. As an experimental result, hard pad showed center-fast type, and soft pad showed edge-fast type. Totally, the defect level has shown little difference, however, the counts of scratch was detected less than 2 on JR111 pad. Through the above results, we can select optimum polishing pad, so we can expect the improvements of throughput and device yield.

• The Journal of Advanced Prosthodontics
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• v.11 no.2
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• pp.128-137
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• 2019

PURPOSE. The aim of this study was to compare the effect of different finishing and polishing techniques on water absorption, water solubility, and microhardness of ceramic or glass-polymer based computer-aided design and computer-aided manufacturing (CAD/CAM) materials following thermocycling. MATERIALS AND METHODS. 150 disc-shaped specimens were prepared from three different hybrid materials and divided into five subgroups according to the applied surface polishing techniques. All specimens were subjected up to #4000 grit SiC paper grinding. No additional polishing has been done to the control group (Group I). Other polishing procedures were as follows: Group II: two-stage diamond impregnated polishing discs; Group III: yellow colored rubber based silicone discs; Group IV: diamond polishing paste; and Group V: Aluminum oxide polishing discs. Subsequently, 5000-cycles of thermocycling were applied. The analyses were conducted after 24 hours, 7 days, and 30 days of water immersion. Water absorption and water solubility results were analyzed by two-way ANOVA and Tukey post-hoc tests. Besides, microhardness data were compared by Kruskal-Wallis and MannWhitney U tests (P<.05). RESULTS. Surface polishing procedures had significant effects on water absorption and solubility and surface microhardness of resin ceramics (P<.05). Group IV exhibited the lowest water absorption and the highest microhardness values (P<.05). Immersion periods had no effect on the microhardness of hybrid ceramic materials (P>.05). CONCLUSION. Surface finishing and polishing procedures might negatively affect physical properties of hybrid ceramic materials. Nevertheless, immersion periods do not affect the microhardness of the materials. Final polishing by using diamond polishing paste can be recommended for all CAD/CAM materials.

• Journal of the Speleological Society of Korea
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• no.82
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• pp.8-12
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• 2007

In this paper, we have investigated the characteristics of the magnetic abrasive using sludge on polishing of internal finishing of seamless stainless steel tube applying magnetic abrasive polishing. Either 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 38% of improvement of surface roughness was achieved when 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 green carborundum grains.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.06a
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• pp.485-485
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• 2009

Double side polishing process has been used for various industrial applications, such as polishing of semiconductor substrates and flat panel display glasses. In wafer manufacturing, double side polishing process is applied to improve wafer flatness and to minimize particle generation from wafers in device manufacturing processes, which is recognized as one of the most important processes. Whereas the kinematical modeling and analysis results of single side polishing, extensively used for chemical-mechanical polishing (CMP) in device manufacturing, are well investigated, the studies in conjunction with double side polishing are barely carried out, due to the complication of polishing system and the uncertainty of wafer motion in the carrier. This paper suggests the derivation of kinematical model with consideration of carrier and wafer motion in double side polishing, and then presents the effect of kinematical parameters on material removal amount and its non-uniformity. The kinematical analysis results help to understand the double side polishing process and to control the polishing results.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2002.04a
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• pp.38-42
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• 2002

In the recent, electro-rheological fluid has been used for micro polishing of the 3-dimensional micro-aspherical lens and some sectional parts with defects on the wide flat wafer. The ER fluid has the properties that its viscosity has drastic changed under some electric fields. Therefore, ER fluid can be applicable to the micro polishing fur some parts using these properties. In this paper, the experimental device has been constructed using the precision milling machine in order to micro polishing far some sectional parts of a 4 inches wafer It is consisted of a small steel electrode, a wafer fixture, DC10mA and 5KV power supply unit, and a controller unit. Using the ER experimental device, possibility of amending for wide flat wafer and micro polishing of some micro part has been analyzed.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.21 no.2
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• pp.246-251
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• 2012

Pulse electrochemical polishing process has been used to improve mechanical properties such as surface roughness and corrosion resistance on conductive metallic materials. In addition, pulse electrochemical polishing process with various frequency may produce a lustrous, smoother, deburred and cleaned surface on workpiece. The aim of this paper is to study surface characteristics of pulse electrochemical polishing for various frequency conditions using AFM to verify localized surface variation in nanometer scale.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.11a
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• pp.77-80
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• 2004

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.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.1832-1835
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• 2003

This paper suggests the selective ultra precision polishing techniques for micro die and mold parts using magnetic-assisted machining. Fabrication of magnetic abrasive particle and their polishing performance are key technology at ultra precision polishing process of micro parts. Conventional magnetic abrasives have disadvantages. which are missing of abrasive particle and inequality between magnetic particle and abrasive particle. So, bonded magnetic abrasive particles are fabricated by several method. For example, plasma melting and direct bonding. Ferrite and carbonyl iron powder are used as magnetic particle where silicon carbide and Al$_2$O$_3$ are abrasive particle. Developed particles are analyzed using measurement device such as SEM. Possibility of magnetic abrasive and polishing performance of this magnetic abrasive particles also have been investigated. After polishing, surface roughness of workpiece is reduced from 2.927 $\mu\textrm{m}$ Rmax to 0.453 $\mu\textrm{m}$ Rmax.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.1682-1687
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• 2003

Die polishing technology is very critical to determine quality and performance of the final products. Generally, the rotation-type tool is used most widely in the polishing process. However it is difficult to make the mirror surface, because the method using the rotation-type tool causes a lot of tiny scratch on the polished surface. This paper proposes a new method using the oscillation-type tool that reduces the scratch and improves the surface roughness. As result. the mirror surface was able to obtain by using the oscillation-type tool. AE is known to be closely related to material removal rate(MRR). As the surface is rougher, MRR gets larger and AE increase. The surface roughness can be indirectly estimated using the AE signal measured during automatic die polishing process. In this study. an AE sensor based monitoring system was developed to investigate the relation the level of AE RMS with the surface roughness during polishing process.