표면 연마 방법에 따른 니티놀 잔류응력 분석

정지선,홍광표,김운용,조명우,Jeong, Ji-Seon,Hong, Kwang-Pyo,Kim, Woon-yong,Cho, Myeong-Woo 한국금형공학회 2017 한국금형공학회지 Vol.11 No.2

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.

MR fluid Jet Polishing 시스템을 이용한 금형코어재료 연마특성에 관한 연구

이정원(J. W. Lee),하석재(S. J. Ha),홍광표(K. P. Hong),조용규(Y. G. Cho),여인규(I. G. Yeo),조명우(M. W. Cho),제태진(T. J. Je) 한국소성가공학회 2012 금형가공 심포지엄 Vol.2012 No.9

Ultra-precision polishing method by using MR fluid was come into the spotlight for the polishing of metal and optical materials. MR jet polishing process can be controlled by changing the viscosity of MR fluid according to imposed magnetic field. The used MR fluid for MR jet polishing process is composed with the mixture of CI particles, DI water, Na₂CO₃, and glycerin. The results can be obtained from the polishing parameters, such as polishing time, magnetic field, stand-off distance, pressure, etc. In this paper, MR jet polishing was applied to polish the nickel and brass surface with the corrosion and chemical resistance. Nickel and Brass mold materials have been used to fabricate the BLU (back light unit) for three-dimensional optical device in mobile display industries. The polishing results were investigated with the polishing time changing. In case of the MR jet polishing, ferromagnetic materials can be able to interrupt due to the cohesive MR fluid more than non-ferromagnetic materials during MR jet polishing. As the results, the surface roughness of brass (Ra=1.82㎚) was better than the one of nickel (Ra=2.24㎚) after 20min.

금합금 연마재 종류에 따른 금합금 소실량과 연마 정도

김명화,임순호,정문규,Kim, Myoung-Hwa,Yim, Soon-Ho,Chung, Moon-Kyu 대한치과보철학회 1997 대한치과보철학회지 Vol.35 No.2

After clinical adjustment of dental casting restoration, re-polishing procedure is recommanded because the smooth gold sureface is lost. But there is the possibility to get more loose contact than that intended by loss of gold alloy according to the kinds of polishing materials and polishing time. Therefore in this study I polished type II gold alloy with 390gm force, 20,000rpm speed, and 8 kinds of gold alloy polishing materials, fabricated by 4 companies and then measured the amount of loss of gold alloy with Surfcorder SEF-30D and observed alloy surfaces polished by 3 brown rubber points with SEM. The amount of loss of gold alloys polished with 8 kinds of polishing materials and the degree of smoothness of gold alloys according to polishing time and polishing materials were compared. The following results were obtained : 1. When the amount of loss of gold alloys polished with 3 kinds of brown rubber point was compared, Alphalex brown point had the most amount of alloy loss, followed in decreasing order by Shofu brown point and Eveflex brown point. There was statistically significant difference in the amount of alloy loss according to polishing materials. 2. When the amount of loss of gold alloys polished with 5 kinds of green rubber point was compared, Shofu green point had the most amount of alloy loss, followed in decreasing order by Alphaflex green point, Dedeco green clasp polisher, and Eveflex green point. There was statistically significant difference in the amount of alloy loss according to polishing materials except Alphaflex green point and Dedeco green clasp polisher. 3. When the amount of loss of gold alloys polished with all kinds of rubber point was compared, there was no significant difference in Eveflex brown point, Alphaflex green point, and Dedeco green clasp polisher. 4. When average amount of alloy loss per 1 revolution by polishing materials was compared, Alphalex brown point had the greatest value as $0.329{\mu}m$ and Shofu supergreen point had the lowest value as $0.022{\mu}m$. 5. When the degree of sureface smoothness of gold alloy polished with 3 kinds of brown rubber point was compared, In Alphalex brown point surface roughness was completely lost after 20 seconds polishing time, in Shofu brown point 30 seconds, in Eveflex brown point 40 seconds. But in every gold alloys fine scratch formed by rubber points was observed. Based on the results of this study, as rubber polishing materials used in polishing of dental casting restoration after clinical adjustment influenced on the tightness of occlusal or proximal contact, we should make dental casting restoration with minimum error through careful laboratory procedure and form very smooth surface of restoration with tripoli and rouge after use of silicone polishing materials.

다양한 세마방법에 따른 유치법랑질 표면 세마효과에 대한 주사전자현미경적 연구

주종인,김종철 大韓小兒齒科學會 1991 大韓小兒齒科學會誌 Vol.18 No.1

The purpose of this study was to investigate the effects of various cleaning and polishing methods on primary enamel surfaces.Thirty-three extracted or exfoliated caries-free primary anterior human teeth were used.The cleaning and polishing methods used in this study were as follows;application of 10% NaOCl,polishing with a rubber cup at a low speed,polishing with a rubber cup and various polishing pastes and powders,and polishing with an air-powder abrasive system(Cleanjet).The following observations were obtained using the SEM: 1.Of all methods,the sixty-second polishing with an air polisher was the most effective one. 2.In the experimental groups of polishing with a rubber cup and various polishing pastes,Ziroxide paste group was the most effective. 3.Linear scratches were found in the experimental groups of Ziroxide,Nupro,and air polisher.Air polisher group produced less scratches than the others. 4.The effect of 10% NaOCl application for 30 seconds and polishing with a Whip-mix powder were lower than those of the other methods.

불화물 도포 전 치면연마 시행여부에 따른 우식예방효과

조민정 ( Min Jung Cho ),하명옥 ( Myung Ok Ha ),오한나 ( Han Na Oh ) 한국치위생학회 2012 한국치위생학회지 Vol.12 No.1

Objectives : This study was carried out to investigate the caries resistant effect of fluoride by dental polishing prior to fluoride application in vitro. Methods : Artificial caries lesion was made on the surface of specimen enamel taken from cow`s permanent cuspid on the part of labial surface after resin embedding and polishing. Artificial dental plaque was formed on the 72 dental specimen with 25~45 VHN(Vickers Hardness Number) which were divided into three groups(fluoride varnish, APF gel, control) with dental polishing and without polishing respectively. Fluoride varnish and APF gel group with 20 second polishing or without polishing were immersed in the artificial saliva respectively. Control group with or without polishing were immersed in the artificial saliva. Results : 1. Significant difference was not found by fluoride varnish between polishing group and non polishing group (p>0.01). 1) polishing group. The changes of Vickers Hardness Number(VHN) were 14.49±13.73. 2) non-polishing group. The changes of VHN were 11.67±5.39. 2. Significant difference was not found by APF gel between polishing group and non polishing group (p>0.01). 1) polishing group. The changes of VHN were 8.48±8.37. 2) non-polishing group. The changes of VHN were 5.32±2.59. Conclusions : Showed no significant difference between polishing group and non-polishing group regardless of fluoride materials (fluoride varnish, APF gel).(J Korean Soc Dent Hygiene 2012;12(1):113-122)

연마방법에 따른 탄성의치의 표면거칠기와 Candida albicans의 부착율 변화

오주원,서재민,안승근,박주미,강철균,송광엽 대한치과보철학회 2012 대한치과보철학회지 Vol.50 No.2

연구 목적: 본 연구는 탄성의치 제작 시 주로 사용되는 polyamide를 수종의 연마방법을 사용하여 처리 후 Candida albicans의 부착정도와 표면거칠기를 비교하고자 하였다. 연구 재료 및 방법: 25×15×2 mm 크기의 polyamide 시편을 4군으로 나누어 연마재를 사용하여 기공용 lathe 연마하는 방법(기공실내 연마방법)과 각기 다른 2종의 실리콘 포인트로 진료실내 연마하는 방법, 그리고 실리콘포인트 연마 후 pumice로 연마하는 방법으로 처리하였다. C. albicans의 부착성을 평가하기 위해 5×106 CFU/ml의 C. albicans 현탁액에 시편을 2시간 동안 침적하였고 5회 수세처리 후 한천배지에서 배양하였다. 그리고 주사전자 현미경(JSM-5900, JEOL LTd., Tokyo, Japan) 촬영을 시행하였다. Profilometer (Surf-pak; Kawasaki, Japan)를 이용하여 표면거칠기를 측정하였고 통계처리를 위하여 SPSS 18.0 프로그램을 사용하였다. 일원변량분석으로 비교 분석하였고 사후검증은 C. albicans의 부착성 검증을 위해 Scheffe test를 시행하였으며 표면조도검증을 위해 Tamhane’s T2 test를 시행하였다(α=.01). 결과: 최대 거칠기 값을 보인 군은 2단계의 연마용 버를 사용한 것으로 0.32 ㎛±0.10 값을 나타냈으며, 가장 낮은 거칠기 값을 보인 것은 tungsten carbide를 사용하지 않고 기공용 lathe로만 연마를 한 군으로 0.02 ㎛±0.00의 거칠기 값을 나타냈다. C. albicans 부착 실험에서는 기공용 lathe만을 이용한 연마방법이 가장 적은 부착수를 보였으며 다른 세 군과 유의한 차이가 발견되었다(P<.01). 결론: 표면거칠기 및 미생물 부착능 실험 결과 기공실 연마만을 시행한 경우 유의하게 낮은 거칠기 값과 부착율을 보였다. Pumice로 추가 연마한 군은 진료실연마를 시행한 군에 비해 낮은 거칠기 값을 보였으나 C. albicans 부착에 있어서는 유의한 차이를 보이지 않았다(P>.01). Purpose: The purpose of this study was to compare the effect of 3 chairside polishing methods and laboratory polishing methods on surface roughness and C. albicans adhesion of polyamide denture base. Materials and methods: Using contact profilometer, the surface of polyamide specimens (25×15×2 mm) was studied after conventional polishing without finishing and after chiarside polishing with 2 chiarside polishing kits and chairside-pumice polishing following finishing with tungsten carbide bur. To evaluate the adhesion of C. albicans, C. albicans suspension was overlayed on the test specimen. And the specimens were incubated for 2 hours. Imprint culture method was achieved and counted the colony on the agar plate. Polished polyamide were evaluated using a scanning electron microscope. The statistics were conducted using one-way ANOVA and in case of difference, Scheffe test and Tamhane’s T2 test were used. Results: Surface roughness (Ra) of surfaces polished with 2 chairside polishing kits had higher than conventional polishing and pumice polishing. The highest roughness value was 0.32 ± 0.10 ㎛, and the lowest was 0.02 ± 0.00 ㎛. The adhesion of C. albicans on the specimens polished with chairside polishing group and pumice polishing group were increased than conventional polishing group (P<.01). Conclusion: Conventional laboratory polishing was found to produce the smoothest surface and the lowest adhesion of C. albicans. Two groups polished with Chairside polishing kits were similar with respect to surface roughness. Surface of the specimen polished with pumice is significantly smoother than 2 chairside polishing groups, but the result of C. albicans adhesion is that group polished with pumice was similar with 2 chairside polishing groups (P>.01).

Manuscript numerical simulation on ultra-precision polishing of monocrystalline silicon by SPH method

Xiu Lei,Lv Gang,Xu Yan,Qiao Yang,Jiang Hai,Wang Xianwei,Ye Xia 대한기계학회 2018 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.32 No.7

Ultra-precision polishing is an important processing method for monocrystalline silicon, in order to improve the machining efficiency and obtain good machining quality, it is necessary to investigate the material removal process and process parameters of ultra-precision polishing. Smoothed particle hydrodynamics (SPH) is a meshless method with good self-adaptability, it can be used in the simulation of ultra-precision polishing which has high speed deformation characteristics. The calculation model and SPH analysis model of ultraprecision polishing are established according to the principle of ultra-precision polishing, SPH method is used to simulate and analyze ultra-precision polishing of the monocrystalline silicon. The material removal process of ultra-precision polishing is investigated, the effects of abrasive size and indentation depth on the equivalent plastic strain (PEEQ), Mises stress and the force of abrasive is investigated. The result is that, at the different time of ultra-precision polishing, the maximum PEEQ is different, but the difference is not obvious; the X direction force of the abrasive increases with the indentation depth; the size of abrasive has a great influence on the soft coefficient of stress state in ultra-precision polishing. According to the simulation results, it is possible to optimize the technological parameters of ultra-precision polishing, and provide the theoretical guidance for practical production.

MR Polishing을 이용한 커버글라스의 굽힘강도 향상에 관한 연구

이정우,김지훈,임동욱,하석재,Lee, Jeong-woo,Kim, Ji-Hun,Lim, Dong-Wook,Ha, Seok-Jae 한국금형공학회 2022 한국금형공학회지 Vol.16 No.1

Coverglass of electronic equipments is thinner and slimmer, so the glass must have good bending strength. In these days, the polishing edge of glass is used by solid tool like grinding wheel. But solid tool leave micro crack or edge chipping in edge of glass. MR polishing is an optimal method by polishing edge of glass. MR polishing is used MR fluid that is a liquid tool. MR polishing doesn't leave tool path or residual stress, micro crack and edge chipping unlike grinding wheel polishing. In this paper, the results of grinding and MR polishing were compared and analyzed to improve bending strength by minimizing edge chipping of cover glass. It was derived that the depth and size of cracks have a significant influence on the bending strength of the glass edge. The edges of the glass using MR grinding were analyzed to have a better surface and higher bending strength than the glass using abrasive wheel grinding. It was confirmed that MR polishing had an effect on strength improvement by effectively removing cracks in the specimen.

여러가지 수복물의 polishing조건에 따른 치수 온도변화

김재곤,이승영,박종하,백병주,양종숙 大韓小兒齒科學會 1999 大韓小兒齒科學會誌 Vol.26 No.2

수복물의 연마의 중요성에 대하여 많은 연구들이 이루어져 왔으며, 이는 수복물의 금속성질의 개선, 변연적합성의 증가 그리고 치태축적의 감소 등을 이유로 시행된다. 그러나 불행하게도 수복물에 대한 연마시 열의 발생으로 인하여 치수부위에 손상을 초래하므로 열의 발생을 최소화하려는 노력이 뒤따라야 할 것이다. 이에 본 연구에서는 수복물의 연마시 회전속도의 차이, 냉각제의 적용 유무, 여러 종류의 수복물의 차이, 간헐적인 연마와 연속적인 연마의 차이 그리고 잔존 상아질의 두께의 정도에 따른 치수내부에서의 열의 변화를 알아보기 위하여 발거된 구치에 5급 와동을 형성한 후 복합레진(Z100, 3M co), resin-mod-ified GLC(Dyract, Fuji II LC), 그리고 아말감(Degussa)등으로 충전하였으며, 다양한 조건에서의 연마를 시행, 치수내부에서의 열의 변화를 측정하여 다음과 같은 결과를 얻었다. 1. Amalgam을 건조한 상태에서 연마시 다른 재료에 비해 큰 치수내 온도 상승을 보였다.(P<0.05). 그러나 Z100, Dyract, Fuji II LC간에는 간헐적 수복물 연마와 연속적인 수복물 연마 모두 어떤 경우든 유의차가 없었다.(P>0.05). 2. 같은 조건으로 연마를 시행했을 때, 간헐적인 연마보다 연속적인 연마를 한 경우가 치수내 온도가 더 크게 상승하였다.(p<0.01). 3. 아말감과 Dyract에 있어서는 잔존 상아질의 차이에 따른 치수내 온도변화에 유의한 차이를 보였으나(P<0.01), Fuji II LC에 있어서는 유의성이 없었다(P>0.01). 4. 냉각제의 유무에는 관계없이 어떤 경우든 시간에 따른 온도 상승을 보였다. 그러나, 냉각제를 사용한 경우가 냉각제를 사용하지 않은 경우에 비해 온도 상승값이 훨씬 작았다.(P<0.01) The importance of finishing and polishing the restoration has been described by several authors. The final step provides for improved metallurgical properties, better marginal adaptation, reduced plaque accumulation. Unfortunately, finishing of the restorations can produce damage from temperature rises at the pulpal wall. The aim of this study was to determine the changes in temperature can be occurred during the use of finishing and polishing instruments under a variety of conditions. ; with or without a water coolant, intermittent or continuous operation, high or low rotation speed, remaining dentin thickness, and various restorative materials. Class V preparations were cut on extracted molars and restored with composite resin(Z 100), resin-modified glass ionomer cements(Dyract, Fuji II LC), and amalgam. Finishing was done with aluminum oxide coated disc(Sof-lex polishing disc, 3M, USA). The following results were obtained. 1. The rise of temperature during polishing of amalgam restorations was the highest among the all experimental groups except polishing with water coolant(P<0.05). However, there were no statictical differences in temperature rises between Z 100, Dyract and Fuji II LC(P>0.05). 2. The intrapulpal temperature was greatly influenced by the applied time, and intermittent polishing was showed significantly lower temperature rises than continuous polishing(p<0.01). 3. The intrapulpal temperature was increased according to the application of polishing regardless of using water coolant. However, polishing with water coolant showed significantly lower temperature in the pulp than not used water coolant(P<0.01).

연마방법에 따른 복합레진의 표면특성 평가

백민경,김종철,장기택 大韓小兒齒科學會 2016 大韓小兒齒科學會誌 Vol.43 No.3

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 (FiltekTM Z250) and nanofilled (FiltekTM 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. 본 연구는 복합레진의 연마방법에 따른 표면특성을 평가하기 위해, microhybrid 레진(FiltekTM Z250)과 nanofill 레진(FiltekTM Z350)을 연마 전, abrasive disk(Sof-lex) 연마 후, polishing brush(Occlubrush) 연마 후로 나누어 분석하였다. 그 결과 레진 표면조도는 연마 후 증가하였는데, 미세조도는 연마방법에 따른 차이가 없었으나 거시조도는 Occlubrush를이용한 경우 현저하게 커졌다(p < 0.05). Sof-lex 연마의 경우 레진의 filler까지 연마되어 표면이 보다 균일한 형상을 보였으나 Occlubrush 연마시편은 기질층이 뜯겨져 나간 불균일한 형상을 보였다. 두 연마방법 간의 미세경도 유의차는 없었으며(p > 0.05), 연마 후 경도 값이 약 25% 상승하였다. 결론적으로, 복합레진의 표면경도 향상을 위하여 적합한 연마가 필요하며, Sof-lex를 이용한 연마가 더 우수한 것으로 사료된다.