• Journal of the Korean institute of surface engineering
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• v.55 no.4
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• pp.236-246
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• 2022

Electropolishing is a surface finishing treatment that compensates for the disadvantages of the mechanical polishing process. It not only has a smooth surface, but also improves corrosion resistance. Therefore, the purpose of this investigation is to examine the corrosion resistance and electrochemical characteristics in seawater of UNS S31603 with electropolishing process time. The roughness improvement rate after electropolishing was improved by about 78% compared to before polishing, indicating that the electropolishing is effective. As a result of potential measuring of mechanical polishing and electropolishing, the potential of electropolishing was nobler than the mechanical polishing condition. As a result of calculating the corrosion current density after potentiodynamic polarization experiment with electropolishing conditions, the corrosion current density of mechanical polishing was about 6.4 times higher than that of electropolishing. After potentiodynamic polarization experiment with electropolishing conditions, the maximum damage depth of mechanical polishing was about 2.2 times higher than that of electropolishing(7 minutes). In addition, the charge transfer resistance of the specimen electropolished for 7 minutes was the highest, indicating improved corrosion resistance.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.16 no.6
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• pp.133-139
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• 2007

In this paper, optics polishing technology using adaptive tool and eccentric motion mechanism was suggested. Optics polishing can make high reflective and accurate surface. The optics polishing process based on the eccentric motion mechanism has been used to manufacture the ophthalmic lens mold. Also ophthalmic lens mold factory hold conventionally a lot of the curved polishing tools for the versatile mold curves of eye diopters and want to reduce tool numbers. Therefore, a polishing machine with adaptive airbag tool was developed and experimentally verified in view of surface roughness and form accuracy.

• Journal of the Korean Ceramic Society
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• v.50 no.2
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• pp.122-126
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• 2013

The surface roughness of the inner and outer surfaces of a tube is an important requirement for nuclear fuel cladding. When an inner SiC clad tube, which is considered as an advanced Pressurized Water Cooled Reactor (PWR) clad with a three-layered structure, is fabricated by Chemical Vapor Deposition (CVD), the surface roughness of the substrate, graphite, is an important process parameter. The surface character of the graphite substrate could directly affect the roughness of the inner surface of SiC deposits, which is in contact with a substrate. To evaluate the effects of the surface roughness changes of a substrate, SiC deposits were fabricated using different types of graphite substrates prepared by the following four polishing paths and heat-treatment for purification: (1) polishing with #220 abrasive paper (PP) without heat treatment (HT), (2) polishing with #220 PP with HT, (3) #2400 PP without HT, (4) polishing with #2400 PP with HT. The average surface roughnesses (Ra) of each deposited SiC layer are 4.273, 6.599, 3.069, and $6.401{\mu}m$, respectively. In the low pressure SiC CVD process with a graphite substrate, the removal of graphite particles on the graphite surface during the purification and the temperature increasing process for CVD seemed to affect the surface roughness of SiC deposits. For the lower surface roughness of the as-deposited interlayer of SiC on the graphite substrate, the fine controlled processing with the completed removal of rough scratches and cleaning at each polishing and heat treating step was important.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.629-632
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• 2005

ELID(ELectrolytic In-process Dressing) grinding is an excellent technique for mirror grinding of various advanced metallic or nonmetallic materials. A polishing process is also required for elimination of scratches present on ELID grinded surfaces. MAP(Magnetic Assisted Polishing) has been used as a polishing method due to its high polishing efficiency and to its resulting in a superior surface quality. This study describes an effective fabrication method combining ELID and MAP of nano-precision mirror grinding for glass-lens molding mould, such as WC-Co, which are extensively used in precision tooling material. And for the optics glass-ceramic named Zerodure, which is extensively used in precision optics components too. The experimental results show that the combined method is very effective in reducing the time required for final polishing. The best surface roughness of the polished glass-ceramic was within 1.7nm Ra in this study.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1997.10a
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• pp.947-952
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• 1997

The magnetic polishing is the useful method to finish using magnetic power of a magnet. The time hasn't been that long since the magnetic polishing method was introduced to korea as one of precision polishing techniques. However, the reasons for not being spreaded widely are the magnetic polishing method don't have mediocrity for machine, the efficiency of magnet-abrasive is confined as a bad polishing, and there are not many researchers in this field. The mechanism of this R&D is dealing with the dynamic state of magnet-abrasive. This paper deals with mediocritizing magnetic polishing device into regular lathe and this experiment was conducted in order to get a best surface roughness with low cost. Beside the subsidiary experiment was performed using the mixed magnet-abrasive with general alumina, barium. This paper introduced the main reason for difficulty using this method in industrial field. It needs more continues research on it. This paper contains the result of experiment to acquire the best surface roughness, not using the high-cost polishing material in processing. The average diameters of magnet-abrasive are the particles of 150 $\mu\textrm{m}$, 250 $\mu\textrm{m}$.

• Journal of the Korean Society for Precision Engineering
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• v.28 no.8
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• pp.929-935
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• 2011

As a deterministic finishing process for the optical parts having complex surface, machining performance of the magnetorheological(MR) fluid jet polishing of optical glass are studied and compared with a general water jet polishing. First, design of the jet polishing system which has the special electromagnet-nozzle unit for stabilizing the slurry jet based on MR fluid and the change of jet shape as magnetic field is applied are explained. Second, for the BK7 glass, machining spot and its cross section profile are analyzed and the unique effect of MR fluid jet polishing is shown. Third, both material removal depth and surface roughness are explored in order to investigate the polishing performance of MR fluid jet. With the same ceria abrasives and amount in the polishing slurries, MR fluid jet shows superior machining performance compared to water jet and the difference of material removal mechanism and its resulting performance are described.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1994.10a
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• pp.98-102
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• 1994

There are many difficulties in automatic polishing for die & mold surfaces. Even though the process has been studied in the past 15 years, it has not been achieved yet, but by the process of actual hand work of well-skilled workers. A new magentic assisted polishing process, which is one of the potential method for automation of surface finishing has been studied in the past 10 years by colleagues. The process has many merits, but on the other hand also has demerits, one being low efficiency of gridability by comparision with grinding wheel polish. Therefore, some attempts were tried to improve the grindability by adopting electropolishing, ultra-high speed milling, 5-axis controlled machine etc... most recently by collegues. This study also aims to improve the efficiency of polishing by introducing the easily-polished shape surface milling method equalizing the tool feed per tooth to the pick feed. This milling method was experimentally confirmed to have sufficient grindability to polish milled surface (with 10 .mu. mRmax surface roughness) into mirror surface (with 0.4 .mu. mRmax surface roughness).

• The Journal of Advanced Prosthodontics
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• v.11 no.1
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• pp.41-47
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• 2019

PURPOSE. Surface finishing of a zirconia restoration is essential after clinical adjustment. Herein, we investigated the effects of a surface finishing protocol for monolithic zirconia on final roughness and bacterial adherence. MATERIALS AND METHODS. Forty-eight disk-shaped monolithic zirconia specimens were fabricated and divided into four groups (n = 12) based on initial surface treatment, finishing, and polishing protocols: diamond bur+polishing bur (DP group), diamond bur+stone grinding bur+polishing bur (DSP group), no diamond bur+polishing bur (NP group), and no diamond bur+stone grinding bur+polishing bur (NSP group). Initial and final surface roughness was measured with a profilometer, and shown using scanning electron microscope. Bacterial adhesion was evaluated by quantifying Streptococcus mutans in the biofilm. Kruskal-Wallis and Mann-Whitney U tests were used to compare results among groups, and two-way analysis of variance was used to evaluate the effects of grinding burs on final roughness (${\alpha}=.05$). RESULTS. The DP group had the highest final Ra value, followed by the DSP, NP, and NSP groups. Use of the stone grinding bur as a coarse-finishing step significantly decreased final Ra values when a diamond bur was used (P<.001). Omission of the stone grinding bur increased biofilm formation on specimen surfaces. Combining a stone grinding bur with silicone polishing burs produced the smallest final biofilm values, regardless of the use of a diamond bur in initial surface treatment. CONCLUSION. Coarse finishing of monolithic zirconia with a stone grinding bur significantly decreased final Ra values and bacterial biofilm formation when surfaces had been roughened by a diamond bur.

• Journal of Technologic Dentistry
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• v.45 no.2
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• pp.39-47
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• 2023

Purpose: This study aimed to confirm the applicability of gloss polishing using automatic barrel finishing with respect to three-dimensional (3D)-printed resin specimens. The surface roughness and grinding angle of the 3D-printed resin specimens were observed with respect to gloss polishing time using automatic dental barrel finishing. Methods: Herein, experiments were conducted on four types of 3D-printed resin specimens. The specimens, with a thickness of 100 ㎛ each, were printed using a 3D printer. Subsequently, light polymerization was performed on these specimens for 15 min. Post this surface treatment, the specimens underwent grinding for 25 min. This process was followed by gloss polishing at 5-min intervals for up to 25 min using automatic dental barrel finishing. The specimens were photographed using a 3D optical microscope, and their surface roughness and grinding angle were measured. Results: The Ra (centerline average roughness) values of all the specimens, except for crown & bridge 10 group and those in the control group that were not polished using automatic barrel finishing, were <0.2 ㎛. However, polishing time needs to be controlled to realize the desired surface roughness and grinding amount considering the hardness of the resin used. Conclusion: Gloss polishing of 3D-printed resin can be realized using automatic dental barrel finishing. However, polishing time needs to be controlled to realize the desired surface roughness and grinding amount considering the hardness of the resin used.

• Restorative Dentistry and Endodontics
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• v.36 no.2
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• pp.119-124
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• 2011

Objectives: The purpose of this experiment was to evaluate four different polishing systems of their polishability and polishing time. Materials and Methods: 4 mm diameter and 2 mm thickness Teflon mold was made. Z-250 (3M ESPE) hybrid composite resin was slightly overfilled and pressed with slide glass and cured with Optilux 501 for 40 sec each side. Then the surface roughness (glass pressed: control group) was measured with profilometer. One surface of the specimen was roughened by #320 grit sand paper and polished with one of the following polishing systems; Sof-Lex (3M ESPE), Jiffy (Ultradent), Enhance (Dentsply/Caulk), or Pogo (Dentsply/Caulk). The surface roughness and the total polishing time were measured. The results were analyzed with one-way ANOVA and Duncan's multiple range test. Results: The surface roughness was lowest in Pogo, and highest in Sof-Lex. Polishing times were shortest with Pogo, and followed by the Sof-Lex, Enhance and Jiffy. Conclusions: One-step polishing system (Pogo) is very effective to get the smooth surface in a short time, therefore it can be recommended for final polishing system of the restoration.