• Elastomers and Composites
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• 제51권4호
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• pp.301-307
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• 2016

Additive manufacturing (AM), so called 3D Printing is a new manufacturing process and is getting attraction from many industries. There are several methods of 3D printing. Among them fused deposition modeling (FDM) type is most widely used by reason of cheap maintenance, easy operation and variety of polymeric materials. Articles manufactured by 3D printing have weak deposition strength compared with conventionally manufactured products. Deposition strength of FDM type 3D printed article is highly dependent of deposition temperature. Subsequently the nozzle temperature in the FDM type 3D printing is very important and it is controlled by heat source in the 3D printer. Nozzle is connected with heat block and barrel, and heat block contains heat source. Nozzle becomes hot through heat conduction from heat source. Nozzle temperature has been predicted for various thermal boundary conditions by computer simulation and compared with experimental measurement. Nozzle temperature highly depends upon thermal conductivities of heat block and nozzle. Simulation results are good agreement with experiment.

• 대한기계학회논문집A
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• 제41권9호
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• pp.839-844
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• 2017

최근 3차원 프린팅 기술은 비약적으로 발전하여 쾌속조형기술의 대명사가 되고 있다. FDM 방식의 3D프린터는 쾌속조형에 사용되는 가장 일반적인 프린터이지만, 열에 취약하고, 출력물의 표면이 매끄럽지 못하는 등의 문제를 가지고 있다. 본 논문에서는 FDM방식의 3D프린터로 ABS재질의 시편을 제작하였고, 아세톤에 시편을 담그는 방식으로 후처리를 수행하였다. 공정시간을 변수로 후처리를 진행하였으며, 처음 5초의 후처리 시간동안에는 시편의 표면조도가 급격하게 개선되는 결과를 획득하였으며, 5초 이후에는 표면조도의 변화정도가 미미하였다. 또한, 이러한 후처리 공정은 적지만 시편의 인장강도와 파단변형률을 상승시키는 결과를 나타내었다.

• International Journal of Internet, Broadcasting and Communication
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• 제16권1호
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• pp.176-181
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• 2024

The desktop-level 3D printing machines makes it easier for independent designers to produce collectible models. Desktop 3D printers that use FDM (Fused Deposition Modeling) technology usually use a minimum nozzle diameter of 0.4mm. When using FDM printers to make Gunpla models, Thin slice structures are prone to slicing errors, which lead to deformation of printed objects and reduction in structural strength. This paper aims to analyze the printing model that produces errors, control a single variable among the three variables of slice layer height, slice wall thickness and filament type for comparative testing, and find a way to avoid gaps. To provide assistance for using FDM printers to build models containing thin-walled structures.

• 한국기계가공학회지
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• 제16권4호
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• pp.1-8
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• 2017

This paper concerns the possibility of 3D printing reverse idle gears for tractor transmission. For the purposes of this experiment, idle gears were manufactured using a SLA 3D printer, FDM 3D printer, and through machining. The accuracy of the idle gears produced in these three different ways were evaluated by the properties of their outer diameter, inner diameter, roundness, concentricity, parallelism, span, backlash, and gear grade. The tooth characteristics of the idle gears were evaluated by their profile, lead, and the pitch of the gears. The results of this experiment determined that the surface conditions created by the finishing process had a significant impact on the dimensional accuracy of the gears and the characteristics of their teeth.

• 한국기계가공학회지
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• 제16권6호
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• pp.101-108
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• 2017

Recently, the patent rights for 3D printing technology have expired, while 3D printers with RP (Rapid Prototyping or Additive Manufacturing) and 3D printing technologies are receiving attention. In particular, the development of 3D printers is rapid in Korea, thanks to the increasing sales and popularity of FDM (Fused Deposition Modeling or Fused Filament Fabrication) 3D printers. However, the quality and productivity of the FDM 3D Printer are not good, so customers prefer the DLP (Digital Light Processing) method to avoid these shortcomings. The DLP method has high quality and productivity. However, because of the stereolithography equipment, it has few studies compared to optimal values for elements then FDM 3D printing study. In this study, to find the optimal conditions for 3D printing with the DLP method, the aim is to obtain the optimal values (strength, final time, quality) by changing the light exposure time, layer thickness, and z-axis speed.

• 한국기계가공학회지
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• 제17권3호
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• pp.93-101
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• 2018

FDM is one of the popular 3D printing technologies because of an inexpensive extrusion machine and multi-material printing. FDM can use thermoplastics such as ABS and PLA. The 3D-printed ABS parts fabricated by FDM are attractive in the automotive industry because of their weight. A 10% reduction in weight can increase the fuel economy by approximately 7%. To use 3D-printed ABS parts as automotive parts, we should evaluate the 3D-printed parts in terms of automotive reliability. In this study, 3D-printed ABS samples were evaluated using Ono's rotary bending fatigue test. We obtained an S-N curve for the 3D-printed ABS specimen from the finite-element analysis. The S-N curve can be useful in early-stage design decisions for 3D-printed ABS parts.

• Elastomers and Composites
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• 제52권3호
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• pp.216-223
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• 2017

The additive manufacturing technology, also called 3D printing, is growing fast. There are several methods for 3D printing. Fused deposition modeling (FDM) type 3D printing is the most popular method because it is simple and inexpensive. Moreover, it can be used for printing various thermoplastic materials. However, it contains the cooling of layered road and causes thermal shrinkage. Thermal shrinkage should be controlled to obtain high-quality products. In this study, temperature distribution and cooling behavior of a layered road with cooling are studied through computer simulation. The thermal shrinkage of the layered road was simulated using the calculated temperature distribution with time. Shape variation of the layered road was predicted as cooling proceeded. Stress between the bed and the layered road was also predicted.This stress was considered as the detaching stress of the layered road from the bed. The simulations were performed for various thermal conductivities and temperatures of the layered road, bed temperature, and chamber temperature of a 3D printer. The simulation results provide detailed information about the layered road for FDM type 3D printing under operational conditions.

• Journal of Yeungnam Medical Science
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• 제40권3호
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• pp.302-307
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• 2023

With recent developments in digital dentistry, research on techniques and materials for three-dimensional (3D) printing is actively underway. We report the clinical applications and outcomes of 3D printing of temporary crowns fabricated with polylactic acid (PLA) using a fused deposition modeling (FDM) printer. Five participants were recruited from among patients scheduled to be treated with a single full-coverage crown at a dental clinic in a university medical center from June to August 2022. We used 3D-printed crowns fabricated with PLA using an FDM printer as temporary crowns and were assessed for discomfort, fracture, and dislodging. The 3D-printed temporary crowns were maintained without fracture, dislodging, or discomfort until the permanent prosthesis was ready. The average time required for printing the temporary crowns was approximately 7 minutes. The 3D printing of temporary crowns with PLA using an FDM printer is a convenient process for dentists. However, these crowns have some limitations, such as rough surface texture and translucency; therefore, the 3D printing process should be improved to produce better prostheses.

• 한국기계가공학회지
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• 제19권1호
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• pp.63-71
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• 2020

Recently, to improve convenience, flexible electronics are quickly being developed for a number of application areas. Flexible electronic devices comprise characters such as being bendable, stretchable, foldable, and wearable. Effectively manufacturing flexible electronic devices requires high efficiency, low costs, and simple processes for manufacturing technology. Through this study, we enabled the rapid production of multifunctional flexible bending sensors using a simple, low-cost Fused Deposition Modeling (FDM) 3D printer. Furthermore, we demonstrated the possibility of the rapid production of a range of functional flexible bending sensors using a simple, low-cost FDM 3D printer. Accurate and reproducible functional materials made by FDM 3D printers are an effective tool for the fabrication of flexible sensor electronic devices. The 3D-printed flexible bending sensor consisted of polyurethane and a conductive filament. Two patterns of electrodes (straight and Hilbert curve) for the 3D printing flexible sensor were fabricated and analyzed for the characteristics of bending displacement. The experimental results showed that the straight curve electrode sensor sensing ability was superior to the Hilbert curve electrode sensor, and the electrical conductivity of the Hilbert curve electrode sensor is better than the straight curve electrode sensor. The results of this study will be very useful for the fabrication of various 3D-printed flexible sensor devices with multiple degrees of freedom that are not limited by size and shape.

• 한국기계가공학회지
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• 제19권1호
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• pp.81-88
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• 2020

In this paper, the performances of the electrical characteristics of the Fused Deposition Modeling (FDM) 3D-printed flexible resistance sensor was evaluated. The FDM 3D printing flexible resistive sensor is composed of flexible-material thermoplastic polyurethane and a conductive PLA (carbon black conductive polylactic acid) polymer. While 3D printing, polymer filaments heat up quickly before being extruded and cooled down quickly. Polymers have poor thermal conductivity so the heating and cooling causes unevenness, which then results in internal stress on the printed parts due to the rapidity of the heating and cooling. Electrical resistance measurements show that the 3D-printed flexible sensor is unstable due to internal stress, so the 3D-printed flexible sensor resistance curve does not match the increases and decreases in the displacement curve. Therefore, annealing was performed to eliminate the mismatch between electrical resistance and displacement. Annealing eliminates residual stress on the sensor, so the electrical resistance of the sensor increases and decreases in proportion to displacement. Additionally, the resistance is lowered in comparison to before annealing. The results of this study will be very useful for the fabrication of various devices that employ 3D-printed flexible sensor that have multiple degrees of freedom and are not limited by size and shape.