• Proceedings of the Korean Society of Precision Engineering Conference
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• 2000.11a
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• pp.330-333
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• 2000

Dimensional accuracy and surface quality are very important in rapid prototyping especially when the models are used for the production of tools. This paper presents the development of benchmarking part to investigate dimensional accuracy and surface finish. A new test part is designed to perform benchmarking of major rapid prototyping processes such as selective laser sintering, laminated object manufacturing, stereolithography apparatus, and fused deposition modeling. The test part design includes basic manufacturing features such as holes, walls, squares, cylinder and etc. In addition, the small features are included in order to evaluate the fine details that can be manufactured by a specific RP process. The CMM program that automatically measures different features in the test part is also developed. The evaluation of accuracy as well as surface roughness are discussed for major rapid prototyping processes.

• CDE review
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• v.2 no.2
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• pp.12-16
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• 1996

Rapid Prototyping(RP)이란 짧은 시간 내에 CAD 그래픽 데이터로부터 3차원 형상의 시제품을 만들어 내는 기술을 일컬으며, 1986년 3D Systems라는 회사에 의하여 상용화된 SLA(Stereolithography Apparatus)방식을 선두로 하여 지난 10년간 급속히 발전을 해왔다. 원하는 형상의 부품을 만들 때 기존의 machining은 원자재에서 재료를 깎아내면서 만드는 반면에, RP는 재료를 한 층씩 차례로 쌓아서 부품을 만드는 가산적인 공정 특징을 가지고 있다. 액체, 고체, 심지어 기체 상태의 재료까지 다양한 재료를 사용하고 있으며 또한 여러가지 적층방법으로 부품을 제작하고 있다. 성공적인 RP기술의 창출에는 RP기계제작에 직접 관계되는 기술뿐만 아니라, 재료 기술, RP제작에 적합한 CAD데이터 생성기술, 후처리 및 가공기술 등이 모두 관건이 된다. 여기서는 RP기술의 주요 파트 제작방법과 RP에 쓰이는 재료, RP의 용도 및 그 한계성 등에 대하여 생각하여 보았다. RP기술은 3차원 CAD 모델이 없으면 실현이 불가능하다. 3차원(3D)화는 제품을 설계하고 만드는 대부분의 회사가 경쟁력을 갖기 위하여 싫든 좋든 이루어야 하는 목표 중의 하나라고 할 수 있는데, RP기술 도입은 이러한 3차원화를 단축시키는 촉매제의 역할을 할 수 있다고 생각한다. RP기술이 부분적으로 정확도의 문제와 제작 가능한 재료의 종류 및 성능에 제한이 있지만, 현재로서도 여러 응용분야에 성공적으로 이용되고 있으며 향후에는 더욱 그 응용 범위를 넓혀갈 것으로 전망된다.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1994.10a
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• pp.884-889
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• 1994

In this work, rapid prototyping and three dimensional finite element analysis are simltaneously applied to design metal forming processes. Rapid prototyping is a new prototyping technology which producess three dimensional part models directly from CAD data and has been extensively applied to various manufacturing processes. There are many types of rapid prototyping systems due to their building principles and materials. In this work, Stereolithography Apparatus (SLA) which is the most widely-used rapid prototyping system is introduced to manufacture the die set. To prepare STL file generally, mesh data which are in describing the die surface in finite element analysis are translated so that rapid prototyping and finite element analysis are effectively connected. The die sets are manufactured using SLA prototypes, and matal forming experiments are carried out using them. Comparing experiments results with analyses, the processes can be predicted and designed successfully.

• Design & Manufacturing
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• v.2 no.2
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• pp.20-24
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• 2008

Recently, the study for production technology is focused on cycle time reduction as various products are manufactured. In order to manufacture tool and die, rapid prototyping and rapid tooling are researched. Stereolithography apparatus, selective laser sintering, 3D printing, laminated object manufacturing are developed in rapid prototype. The purpose of this study is to develop rapid tooling technology using thermal spray process. This technology is not well-known to korea, but this study will be contributed in development of domestic molds industry through continuous research and development.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.10a
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• pp.514-517
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• 2005

Microstereolithography(MSL) has evolved from the stereolithography technique, and is also based on a light-induced layer-stacking fabrication. Although integral MSL allows the manufacture of a complete layer by one irradiation only, there is a problem related with shape precision due to the light-intensity distribution of focused image. In this study, we developed the integral MSL apparatus using Digital Micromirror Device ($DMD^{TM})$, Texas Instruments) as dynamic pattern generator. It is composed of Xenon-Mecury lamp, optical devices, pattern generator, precision stage, controllers and the control program. Also, we have studied curing depth and width of photocurable resin according to the change of exposure energy.

• Journal of the Korean Society for Precision Engineering
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• v.16 no.11
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• pp.74-80
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• 1999

In this study, a stereolithography apparatus (SLA) prototype is used as a master model to be transformed into the silicone pattern by vacuum tool forming. The tool for the first prototype is fabricated by using this silicone pattern. Following this procedure, a temporary tool with metal powder and epoxy for wax injection is prepared for the die set of quick change type which consists of upper and lower base die나 and an insert die. The die set of quick change type appears to be very effective in casting operation by changing tools rapidly. The original wax pattern is formed through the die set, and is made of lost-was. Finally the lost-wax pattern is applied to investment casting. The final casting product is checked regarding its dimensional accuracy.

• The Journal of Korean Academy of Prosthodontics
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• v.58 no.1
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• pp.7-13
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• 2020

Purpose: This study was to evaluate marginal and internal discrepancy of 3-unit fixed dental prostheses (FDP) fabricated by subtractive manufacturing and additive manufacturing. Materials and methods: 3-unit bridge abutments without the maxillary left second premolar were prepared (reference model) and the reference model scan data was obtained using an intraoral scanner. 3-unit fixed dental prostheses were fabricated in the following three ways: Milled 3-unit FDP (MIL), digital light processing (DLP) 3D printed 3-unit FDP (D3P), stereolithography apparatus (SLA) 3D printed 3-unit FDP (S3P). To evaluate the marginal/internal discrepancy and precision of the prosthesis, scan data were superimposed by the triple-scan protocol and the combinations calculator, respectively. Quantitative and qualitative analysis was performed using root mean square (RMS) value and color difference map in 3D analysis program (Geomagic control X). Statistical analysis was performed using the Kruskal-Wallis test (α=.05), MannWhitney U test and Bonferroni correction (α=.05/3=.017). Results: The marginal discrepancy of S3P group was superior to MIL and D3P groups, and MIL and D3P groups were similar. The D3P and S3P groups showed better internal discrepancy than the MIL group, and there was no significant difference between the D3P and S3P groups. The precision was excellent in the order of MIL, S3P, and D3P groups. Conclusion: Within the limitation of this study, the 3-unit fixed dental prostheses fabricated by additive manufacturing showed better marginal and internal discrepancy than the those of fabricated by subtractive manufacturing, but the precision was poor.

• Journal of radiological science and technology
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• v.40 no.3
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• pp.433-441
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• 2017

The 3D printing selective laser sintering (SLS) and stereo lithography apparatus (SLA) method used for bone model production has good precision and resolution, but the printers are expensive and need professional knowledge for operation. The program that converts computed tomography digital imaging and communications in medicine (DICOM) file into STL (stereolithography) file is also expensive so requesting 3D printing companies takes a lot of time and cost, which is why they are not generally utilized in surgery. To produce bone models of fractured patients, the use of 3D imaging conversion program and 3D printing system should be convenient, and the cost of device and operation should be low. Besides, they should be able to produce big size bone models for application to surgery. Therefore, by using an fused deposition modeling (FDM) method 3D printer that uses thermoplastic materials such as DICOM Viewer OsiriX and plastic wires, this study developed 3D printing system for Fracture surgery Patients customized bone model production for many clinics to use for surgery of fracture patients by universalizing with no limit in printing sizes and low maintenance and production cost. It is expected to be widely applied to the overall areas of orthopedics' education, research and clinic. It is also expected to be conveniently used in not only university hospitals but also regular general hospitals.

• The Journal of Korean Academy of Prosthodontics
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• v.57 no.3
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• pp.225-231
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• 2019

Purpose: This study was undertaken to compare fracture and flexural strength of provisional restorative resins fabricated by additive manufacturing, subtractive manufacturing, and conventional direct technique. Materials and methods: Five types of provisional restorative resin made with different methods were investigated: Stereolithography apparatus (SLA) 3D printer (S3Z), two digital light processing (DLP) 3D printer (D3Z, D3P), milling method (MIL), conventional method (CON). For fracture strength test, premolar shaped specimens were prepared by each method and stored in distilled water at $37^{\circ}C$ for 24 hours. Compressive load was measured using a universal testing machine (UTM). For flexural strength test, rectangular bar specimens ($25{\times}2{\times}2mm$) were prepared by each method according to ISO 10477 and flexural strength was measured by UTM. Results: Fracture strengths of the S3Z, D3Z, and D3P groups fabricated by additive manufacturing were not significantly different from those of MIL and CON groups (P>.05/10=.005). On the other hand, the flexural strengths of S3Z, D3P, and MIL groups were significantly higher than that of CON group (P<.05), but the flexural strength of D3Z group was significantly lower than that of CON group (P<.05). Conclusion: Within the limitation of our study, provisional restorative resins made from additive manufacturing showed clinically comparable fracture and flexural strength as those made by subtractive manufacturing and conventional method.

• Korean Chemical Engineering Research
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• v.62 no.1
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• pp.105-111
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• 2024

The SLA (Stereolithography Apparatus) method is a type of 3D printing technique predicated on the transformation of liquid photocurable resin into a solid form through UV laser exposure, and its application is increasing in various fields. In this study, we conducted research to enhance the hydrophobicity and transparency of SLA 3D printing surfaces for microfluidic system production. The enhancement of surface hydrophobicity in SLA outputs was attainable through the application of hydrophobic coating methods, but the coating durability under different conditions varied depending on the type of hydrophobic coating. Additionally, to simultaneously achieve the required transparency and hydrophobic properties for the fabrication of microfluidic systems, we applied hydrophobic coatings to the proposed transparency enhancement method from prior research and compared the changes in contact angles. Teflon coating was proposed as a suitable hydrophobic coating method for the fabrication of microfluidic systems, given its excellent transparency and high coating durability in various environmental conditions, in comparison to titanium dioxide coating. Finally, we produced an Electrophoresis of Charged Droplet (ECD) chip, one of the digital microfluidics systems, using SLA 3D printing with the proposed Teflon coating method (Fluoropel 800). Droplet manipulation was successfully demonstrated with the fabricated chip, confirming the potential application of SLA 3D printing technology in the production of microfluidic systems.