전사방식 광조형 시스템의 해상도 최적화를 통한 출력물의 정밀도 향상

김영흠(Yeong-Heum Kim),김규언(Kyu-Eon Kim),이치범(Chibum Lee) 한국생산제조학회 2015 한국생산제조학회지 Vol.24 No.6

Projection stereolithography is an additive manufacturing method that uses beam projection to cure the photo-reactive resin used. The light source of a crosssection layer-form illuminates photo-curable resin for building a threedimensional (3D) model. This method has high accuracy and a fast molding speed because the processing unit is a face instead of a dot. This study describes a Scalable Projection Stereolithography 3D Printing System for improving the accuracy of the stereolithography. In a conventional projection 3D printer, when printing a small sized model, many pixels are not used in the projection or curing. The proposed system solves this problem through an optical adjustment, and keeps using the original image as possible as filling the whole projection area. The experimental verification shows that the proposed system can maintain the highest level of precision regardless of the output size.

3-Dimensional Circuit Device Fabrication Process using Stereolithography and Direct Writing

장성현,오성택,이인환,김호찬,조해용 한국정밀공학회 2015 International Journal of Precision Engineering and Vol.16 No.7

Additive manufacturing (AM) technology is a method to fabricate a 3-dimensional structure by stacking thin layers. Among AM technologies, it is known that stereolithography (SL) technology can fabricate a structure having high dimensional accuracy. Recently, this technology is being applied for real manufacturing. Meanwhile, direct writing (DW) technology has been used to apply a lowviscosity liquid material on a substrate. In this regards, in this research, we applied the DW technology to deposit a conductive material on the surface of a three-dimensional structure. Moreover, a three-dimensional circuit device (3DCD) which is different from conventional two-dimensional PCBs can be fabricated by the hybrid process of SL and DW technologies. An insulated structure of circuit board having high precision was fabricated using stereolithography. Furthermore, a circuit is fabricated on the several layers using DW. And the 3DCD sample that detects a light was fabricated, successfully.

Liquid Bridge Stereolithography: A Proof of Concept

조광호,이석희,최재원 한국정밀공학회 2018 International Journal of Precision Engineering and Vol.19 No.8

Stereolithography (SL) is an additive manufacturing (AM) process that uses photopolymers for creating a 3D structure that has excellent surface roughness and allows precision fabrication. Nevertheless, the photopolymer used in this process is generally costly, in particular for medical-grade materials, and a relatively large amount of a photopolymer is required within vat that is necessary for this process. To overcome these disadvantages, a liquid bridge of a photopolymer formed between two plates has been suggested as an alternative to using a vat; a liquid bridge requires less photopolymer, resulting in cost savings. The proposed manufacturing platform utilizes Digital Light Processing (DLP) technology and the constrained surface method. Stacking directions using the suggested liquid bridge method have been investigated to evaluate the stability of the process, in which a liquid bridge of a photopolymer is formed between two substrates and a 3D structure is built within the liquid bridge. Finally, several manufacturing examples are introduced to prove the concept of liquid bridge SL and verify its advantage of material savings.

광조형물의 지지대 접촉면적 계산방안

안대건(Dae Keon Ahn),송정일(Jeong Il Song),권순만(Soon Man Kwon),이석희(Seok Hee Lee) 대한기계학회 2008 대한기계학회 춘추학술대회 Vol.2008 No.5

Stereolithography(SL) technology utilizes layered manufacturing(LM) process, which fabricates 3D physical models by stacking 2D layers. Hence, 3D physical model can be manufactured without geometric restrictions. However, part deformation occurs by stacking the layers in overhanging area. Support structure is used to prevent the deformation. After finishing build process, the support is removed from the part. But support removal burrs remain on the surface of the part so that the surface quality becomes poor. As a result, the required cost and time increase in the post processing stage. Therefore, minimization of support contact area (SCA) is required. In this paper, a computation methodology of the SCA is presented as a preparatory research related with SCA minimization in stereolithography. The STL file is directly used to compute the SCA of the 3D model including free formed surface. By several examples, it is demonstrated that the proposed methodology can be effective.

Effect of post-rinsing time and method on accuracy of denture base manufactured with stereolithography

Awutsadaporn Katheng,Manabu Kanazawa,Yuriko Komagamine,Maiko Iwaki,Sahaprom Namano,Shunsuke Minakuchi 대한치과보철학회 2022 The Journal of Advanced Prosthodontics Vol.14 No.1

PURPOSE. This in vitro study investigates the effect of different post-rinsing times and methods on the trueness and precision of denture base resin manufactured through stereolithography. MATERIALS AND METHODS. Ninety clear photopolymer resin specimens were fabricated and divided into nine groups (n = 10) based on rinsing times and methods. All specimens were rinsed with 99% isopropanol alcohol for 5, 10, and 15 min using three methods-automated, ultrasonic cleaning, and hand washing. The specimens were polymerized for 30 min at 40°C. For trueness, the scanned intaglio surface of each SLA denture base was superimposed on the original standard tessellation language (STL) file using best-fit alignment (n = 10). For precision, the scanned intaglio surface of the STL file in each specimen group was superimposed across each specimen (n = 45). The root mean square error (RMSE) was measured, and the data were analyzed statistically through one-way ANOVA and Tukey test (α < .05). RESULTS. The 10-min automated group exhibited the lowest RMSE. For trueness, this was significantly different from specimens in the 5-min hand-washed group (P < .05). For precision, this was significantly different from those of other groups (P < .05), except for the 15-min automated and 15-min ultrasonic groups. The color map results indicated that the 10-min automated method exhibited the most uniform distribution of the intaglio surface adaptation. CONCLUSION. The optimal postprocessing rinsing times and methods for achieving clear photopolymer resin were found to be the automated method with rinsing times of 10 and 15 min, and the ultrasonic method with a rinsing time of 15 min.

Three-dimensional Bio-printing Technique: Trend and Potential for High Volume Implantable Tissue Generation

Duong, Van-Thuy,Kim, Jong Pal,Kim, Kwangsoo,Ko, Hyoungho,Hwang, Chang Ho,Koo, Kyo-in The Korean Society of Medical and Biological Engin 2018 의공학회지 Vol.39 No.5

Recently, three-dimensional (3D) printing of biological tissues and organ has become an attractive interdisciplinary research topic that combines a broad range of fields including engineering, biomaterials science, cell biology, physics, and medicine. The 3D bioprinting can be used to produce complex tissue engineering scaffolds based on computer designs obtained from patient-specific anatomical data. It is a powerful tool for building structures by printing cells together with matrix materials and biochemical factors in spatially predefined positions within confined 3D structures. In the field of the 3D bioprinting, three major categories of the 3D bioprinting include the stereolithography-based, inkjet-based, and dispensing-based bioprinting. Some of them have made significant process. Each technique has its own advantages and limitations. Compared with non-biological printing, the 3D bioprinting should consider additional complexities: biocompatibility, degradability of printing materials, cell types, cell growth, cell viability, and cell proliferation factors. Numerous 3D bioprinting technologies have been proposed, and some of them have been making great progress in printing several tissues including multilayered skin, cartilaginous structures, bone, vasculature even heart and liver. This review summarizes basic principles and key aspects of some frequently utilized printing technologies, and introduces current challenges, and prospects in the 3D bioprinting.

High-Speed Printing Process Characterization using the Lissajous Trajectory Method

이상원,김대근 한국물리학회 2018 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.72 No.8

We present a novel stereolithographic three-dimensional (3D) printing process that uses Lissajous trajectories. By using Lissajous trajectories, this 3D printing process allows two laser-scanning mir- rors to operate at similar high-speed frequencies simultaneously, and the printing speed can be faster than that of raster scanning used in conventional stereolithography. In this paper, we first propose the basic theoretical background for this printing process based on Lissajous trajectories. We also characterize its printing conditions, such as printing size, laser spot size, and minimum printing resolution, with respect to the operating frequencies of the scanning mirrors and the capability of the laser modulation. Finally, we demonstrate simulation results for printing basic 2D shapes by using a noble printing process algorithm.

비골을 이용한 3차원적 하악골 재건 시 가상모의수술 및 입체조형기법을 이용한 골절단 가이드의 활용: 증례보고

Nam, Woong,Makhoul, Nicholas,Ward, Brent,Helman, Joseph I.,Edwards, Sean 대한악안면성형재건외과학회 2012 Maxillofacial Plastic Reconstructive Surgery Vol.34 No.5

The osseous or osteocutaneous free fibula flap has become the gold standard for most mandibular reconstructions because of its favorable osseous characteristics. However, disadvantages, such as the time-consuming reconstructive step, difficulty in performing the osteotomies to precisely recreate the shape of the missing segment of mandible and poor bone-to-bone contact play a role in making the surgeons look for alternative flaps. With the advent of computerized design software, which accurately plans complex 3-dimensional reconstructions, has become a process that is more efficient and precise. However, the ability to transfer the computerized plan into the surgical field with stereolithographic models and guides has been a significant development in advancing reconstruction in the maxillofacial regions. The ability to "pre-plan" the case, mirror and superimpose natural structures into diseased and deformed areas, as well as the ability to reproduce these plans with good surgical precision has decreased overall operative time, and has helped facilitate functional and esthetic reconstruction. We describe a complex case treated with this technique, showing the power and elegance of computer assisted maxillofacial reconstruction from the University of Michigan, Oral and Maxillofacial Surgery.

Additively Manufactured Lattice Structures and Materials: Present Progress and Future Scope

Ganesh P. Borikar,Ashutosh R. Patil,Snehal B. Kolekar 한국정밀공학회 2023 International Journal of Precision Engineering and Vol.24 No.11

Lattice patterns are designed to create lighter and stronger structures for various industrial applications. With progress in additive technology, lattice structure investigations have become feasible and realistic for efficient product and structural developments. The present study provides an overview of additively manufactured lattice structures along with their cell types, properties, model analysis, printing, and testing mechanical behaviour with adapted materials. The study focus on the behaviour of polymer lattice structures, including thermoplastics and resins, studying energy absorption, weight minimization, improvement of mechanical properties, and failure modes. Systematic literature research has been carried out (from 2006 to 2023) to highlight research gaps and challenges associated with lattice structures, simulation modelling, 3D prints, and structural tests. The study portrays insufficient investigations on fused deposition modelling and stereolithography-based lattice structures with polymers, composites, and metals, limited lattice structures comparative output data, design not withstanding specific energy absorption, low mechanical properties of materials and lattice, lag on the ceramic resins study. The authors report that by applying topology optimisation, comparison, and combination of lattice structures, the use of functionally graded materials, multi-material structures, controlled porosity and flexibility, they can resolve these challenges. The authors are hopeful that this research will be useful for next generation researchers and practitioners in miniaturisation and green product development.

UV-LED를 이용한 광조형 장치 개발

윤해룡(Hae-yong Yun),고태조(Tae-Jo Ko),김호찬(Ho-Chan Kim) 한국기계가공학회 2014 한국기계가공학회지 Vol.13 No.2

The stereolithography(SL) process is a type of fabrication technology which relies on photopolymerization. It has a relatively simple fabrication process and a resolution of several tens of μm. Recently, SL technology has been applied to various areas, such as bioengineering and MEMS devices, due to the development of advanced materials. This technologycan be divided in to the scanning(SSL) and projection (PSL) types. In this paper, in stereolithography, parts are fabricated by curing photopolymeric resins with light. The application of stereolithography can now include fabricated parts. This process, called stereolithography, can fabricate parts by taking into account their degrees of geometry complexity. In particular, UV-LED stereolithography can perform quite rapid fabrication in which specific cross-sections are cured upon exposure to light.