• The Journal of Advanced Prosthodontics
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• v.10 no.2
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• pp.132-137
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• 2018

PURPOSE. The purpose of this study was to evaluate and compare three polishing systems on the surface roughness and phase transformation of monolithic zirconia. MATERIALS AND METHODS. 100 disk shaped specimens (10 mm diameter, 3 mm thickness) were fabricated from monolithic zirconia blocks. 20 specimens were left as a control group and remaining specimens were grinded by diamond bur to simulate the occlusal adjustments. Grinded specimens were randomly divided into 4 groups: group G (no polishing), group M (Meisinger, zirconia polishing kit), group E (EVE Diacera, zirconia polishing kit), and group P (EVE Diapol, porcelain polishing kit). Surface roughness was measured with profilometer and surface topography was observed with SEM. XRD analysis was performed to investigate the phase transformation. Statistical analysis was performed with one-way ANOVA and Tukey's post hoc tests at a significance level of P=.05. RESULTS. All polishing groups showed a smoother surface than group G. Among 3 polishing systems, group M and group E exhibited a smoother surface than the group P. However, no significant differences were observed between group M and group E (P>.05). Grinding and polishing did not cause phase transformations in zirconia specimens. CONCLUSION. Zirconia polishing systems created a smoother surface on zirconia than the porcelain polishing system. Phase transformation did not occur during the polishing procedure.

• The Journal of Korean Academy of Prosthodontics
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• v.36 no.4
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• pp.549-565
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• 1998

Porcelain is considered to be one of the materials of choice for restoration where esthetics is of concern. But porcelain surface without final glazing treatment may induce undesirable results such as inflammatory response on adjacent soft tissues due to plaque accumulation and increased wear of opposing teeth. Therefore, rough porcelain surface must be smoothened by final glazing treatment or chairside polishing procedure. The purpose of this study was to compare the surface roughness among self-glazed, overglazed and polished porcelain with various polishing kit, and to detect which phase of polishing is optimal in clinic. Specimens were fabricated with Vita VMK porcelain. The surface treatment of each group was performed as follows. Group 1 : overglazing treatment Group 2 : self-glazing treatment Group 3 : polishing with the Truluster Polishing System for Porcelain(Brasseler, U.S.A.) Group 4 : polishing with the Exa Cerapol Adjustment kit (Edenta dental products, Switzerland) followed by finishing with diamond-filled polishing paste Group 5 : polishing with the Shofu Porcelain Adjustment kit (Shofu inc., Japan) followed by finishing with diamond-filled polishing paste. At each polishing steps, the measurement of Ra and Rq values were performed, and the surface was examined by scanning electron microscope. The results were as follows : 1. Overglazing treatment brought smoother surface than self-glazing treatment. 2. Polishing systems without porcelain polishing paste did not make better result than self-glazing treatment. 3. Polishing system with porcelain polishing paste made similar result to overglazing treatment. 4. Applying diamond-filled polishing paste after using polishing system which has no porcelain polishing paste produced surface as smooth as overglazing treatment does.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.15 no.1
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• pp.119-126
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• 2006

The finishing process of die requires the processing technique of a height efficiency and precision. Because the precision of die gives the quality of goods the influence directly. The hydro-static polishing device employs the hydro-static axis and is able to polish the structure of complex picture under the constant pressure and is got constant surface roughness at all polished plane. Therefore, In order to polish precision sculptured surface, it was used the hydro-static polishing device. Polishing device's polishing characteristic is estimated by polishing conditions which are size of abrasive, material of tools. And, because the surface quality of workpiece depends on polishing pattern which relates to motion of abrasive grain. The polishing characteristic according to polishing pattern was evaluated.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.20 no.10
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• pp.839-845
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• 2007

In this paper, a polishing pad has been analyzed in detail, to understand surface phenomena of polishing process. The polishing pad plays a key role in polishing process and is one of the important layer in polishing process, because it is a reaction layer of polishing[1]. Pad surface physical property is also ruled by pad profile. The profile and roughness of pad is controlled by different types of conditioning tool. Conditioning tool add mechanical force to pad, and make some roughness and profile. Formed pad surface will affect on polishing performance such as RR (Removal Rate) and uniformity in CMP Pad surface condition is changed by conditioning tool and dummy run and is stable at final. And this research, we want to reduce break-in and dummy polishing process by analysis of pad surface and artificial machining to make stable pad surface. The surface treatment or machining enables to control the surface of polishing pad. Therefore, this research intends to verify the effect of the buffing process on pad surface through analysis of the removal rate, friction force and temperature. In this research, urethane polishing pad which is named IC pad(Nitta-Haas Inc.) and has micro pore structure, is studied because, this type of pad is most conventional type.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.14 no.6
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• pp.136-141
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• 2015

Laser surface polishing is a polishing method for improving surface roughness using an integrated laser beam. Using a laser for surface polishing can improve the surface condition without physical contact or chemical action. Laser polishing has mainly been used to polish the surface of diamond or optical articles, such as lenses and glasses. Recently, diverse studies on laser polishing for metals have been conducted. The analytic study of laser surface polishing has been conducted with experimental trials for comparison, so that the proper conditions for laser polishing can be recommended. In this study, laser surface polishing was simulated in order to predict the heat-affected zone on the die steel depending on the power of the pulsed laser. The simulated results were verified by comparing them to those of the experimental trials. Through this study, therefore, the application of FEM to the selection of appropriate laser conditions could be possible.

• 제어로봇시스템학회:학술대회논문집
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• 1996.10b
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• pp.1312-1315
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• 1996

Polishing work for a curved surface die demands simple and repetitive operations and requires much time while it also demands high precision. Therefore it is operated by skilled worker in handiwork. But workers avoid polishing work gradually because of the poor environments such as dust and noise. In order to reduce the polishing time and to alleviate the problem of shortage of skilled workers, researches for automation of polishing have been pursued in the developed countries such as Japan. In this research we develop a polishing robot with 2 degrees of freedom motion and pneumatic system, and attach it to machining center with 3 degrees of freedom to form an automatic polishing system which keeps the polishing tool vertically on the surface of die and maintains constant pneumatic pressure. The developed polishing robot is controlled by real time sliding mode control using DSP(digital signal processor). A synchronization between machining center and polishing robot is accomplished by using M code of machining center. A performance experiment for polishing work is executed by the developed polishing robot.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2003.10a
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• pp.318-323
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• 2003

In order to polish complicated shaped inner surfaces of molds, a new polishing method with consolation liquid was Invented The MAGIC (MAGnetic Intelligent Compound) Polishing is the best method, a countermeasure of polishing trouble that is reduce of productivity and instability of quality. But because MAGIC polishing is new polishing method there is no study of the standardization of polishing by MAGIC wheel yet. So we want to standadize MAGIC polishing condition. For the First time, we will evaluate the influence of composition ratio and kind of polishing grain in polishing surface roughness. In this study, we determined amount of dressing oil and dressing point as kind and composition ratio of polishing grain. we compared surface roughness case by case

• The Journal of Korean Academy of Prosthodontics
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• v.34 no.2
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• pp.246-265
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• 1996

After adjusting glazed surface of laminate veneer porcelain by reduction in the clinical procedure, an additional polishing procedure is required to smoothen the roughened surface by reduction, as it is difficult to glaze it again in the furnace. In this study, four kinds of laminate veneer porcelain were ground with diamond points as done in the clinical procedure. The adjusted porcelain surface was polished with Durawhite stone, Ceramiste points, Exa cerapol, Porcelain polishing wheel, Diamond polishing paste. The degree of surface roughness was evaluated with SEM and profilometer at each step, The self glazed surface and the glazed surface with glazing powder were compared with the polished surface and surface roughness of four kinds of laminate veneer porcelain according to the polishing method and step were obserbed. The following results were obtained : 1. There was no difference in the average surface roughness Ra value and the surface roughness obserbed under SEM according to the polishing methods and steps used, among the four kinds of laminate veneer porcelain including Colorlogic, Exelco, Vintage, and Vitadur alpha product. 2. Due to porosities, the surface in the course of polishing by polishing instruments was rougher than the glazed surface, evaluated with a SEM. 3. Insta-Glaze diamond polishing paste has no statistical difference with self glazed group 1, although it has a lower value in average surface roughness Ra value. 4. Group 2 which was glazed with galzing powder was lowest in view of SEM, but it revealed higher surface roughness Ra value than group 1, the glazed surface and group 8, polished by diamond polishing paste, due to surface waveness. 5. Proper surface smoothness could not be in the surface roughness analysis of SEM and profilometer by Shofu laminate polishing kit composed of Diamond point, Durawhite stone and Ceramiste points. Based on the results of this study, the following conclusions can be drawn. We obtain low surface roughness than glazed surface by polishing instruments, but not perfect results clinically. In order to obtain a perfect clinical result or a surface smoothness comparable to glazed porcelain there is a need for further improvement of porcelain materials, condensa-tion techniques, polishing instruments and polishing methods. Furthermore card should be taken not to breakdown the glazed surface during the clinical and laboratory procedure.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.1579-1582
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• 2005

Polishing is cutting process that polished workpiece by relative motion of abrasive grain between polishing tool and workpiece. According to relative motion forms(polishing patterns) of abrasive grain, the surface quality is different. Then, polishing patterns are important essential in polishing process. In work field, polishing patterns are determined by an expert of experience. Therefore, to work effective polishing, it is necessary that evaluate polishing characteristics for polishing patterns. And, polishing machine is made with cartesian coordinate robots, we estimate polishing characteristics by measurement of surface roughness.

• Design & Manufacturing
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• v.11 no.2
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• pp.51-56
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• 2017

Nitinol, a shape memory alloy (SMA), is manufactured from titanium and nickel and it used in various fields such as electrical applications, micro sensors. It is also recommended as a material in medical for implant because it has excellent organic compatibility. Nitinol is intended to be inserted into the human body, products require a high-quality surface and low residual stress. To overcome this problems, explore electrolyte polishing (EP) is being explored that may be appropriate for use with nitinol. EP is a particularly useful machining method because, as a non contact machining method, it produces neither machining heat nor internal stress in the machined materials. Sandpaper polishing is also useful machining method because, as a contact machining method, it can easily good surface roughness in the machined materials. The electrolyte polishing (EP) process has an effect of improving the surface roughness as well as the film polishing process, but has a characteristic that the residual stress is hardly generated because the work hardened layer is not formed on the processed surface. The sandpaper polishing process has the effect of improving the surface roughness but the residual stress remains in the surface. We experimented with three conditions of polishing process. First condition is the conventional polishing. Second condition is the electrochemical polishing(EP). And Last condition is a mixing process with the conventional polishing and the EP. Surface roughness and residual stress of the nitinol before a polishing process were $0.474{\mu}mRa$, -45.38MPa. Surface roughness and residual stress of the nitinol after mixing process of the conventional polishing and the EP were $1.071{\mu}mRa$, -143.157MPa. Surface roughness and residual stress of the nitinol after conventional polishing were $0.385{\mu}mRa$ and -205.15MPa. Surface roughness and residual stress of sandpaper and EP nitinol were $1.071{\mu}mRa$, -143.157MPa. The result shows that the EP process is a residual stress free process that eliminates the residual stress on the surface while eliminating the deformed layer remaining on the surface through composite surface machining rather than single surface machining. The EP process can be used for biomaterials such as nitinol and be applied to polishing of wafers and various fields.