• Journal of the Korean Crystal Growth and Crystal Technology
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• v.33 no.6
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• pp.276-281
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• 2023

With the high design freedom of the additive manufacturing process, there is a growing interest in multi-dimensional lattice structures among researchers, who are studying intricate structural modeling that is challenging to produce using conventional manufacturing processes. In the case of titanium alloy implants for human insertion, a multi-dimensional lattice structure is employed to ensure compatibility with bones, adjusting strength and elastic modulus to levels similar to those of bones. Therefore, securing a database on the mechanical properties based on lattice structure design variables and the development of related simulation techniques are believed to efficiently facilitate the customization of implants. In this study, lattice structures were additively manufactured using Ti-6Al-4V alloy, and the elastic modulus was measured based on design parameters. The results were compared with simulations, and an approach to finite element analysis for accurate prediction of the elastic modulus was proposed.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.33 no.6
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• pp.268-275
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• 2023

This paper delves into the crucial realm of support structures in metal additive manufacturing (AM) processes and their direct impact on the stiffness of printed components. With the continuous evolution of AM technologies, optimizing support structures has become imperative to enhance the overall quality and performance of manufactured metal parts. Therefore, in this study, tensile specimens were manufactured using various representative support design variables such as support type, spacing, and penetration depth, and the differences in displacement-load curve were analyzed though tensile test. Using additively manufactured support shaped tensile specimen, the paper presents a comprehensive examination of the effect of support parameters on their stiffness. The findings contribute to advancing the understanding how to design supports to suppress thermal deformation of metal parts during AM process, thereby paving the way for enhanced design freedom and functional performance in the ever-expanding field of AM.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.30 no.2
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• pp.153-162
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• 2020

Objectives: 3D printing technologies have become widely developed and are increasingly being used for a variety of purposes. Recently, the evaluation of 3D printing operations has been conducted through chamber test studies, and actual workplace studies have yet to be completed. Therefore, the objective of this study was to determine the emission of volatile organic compounds(VOCs), metals, and particles from printing operations at a workplace. This included monitoring conducted at a commercial 3D printing service workplace where the processes involved material extrusion, material jetting, binder jetting, vat photo polymerization, and powder bed fusion. Methods: Area samples were collected with using a Tenax TA tube for VOC emission and MCE filter for metals in the workplace. For particle monitoring, Mini Particle Samplers(MPS) were also placed in the printer, indoor work area, and outdoor area. The objective was to analyze and identify particles' size, morphology, and chemical composition using transmission electron microscopy with energy dispersive spectroscopy(TEM-EDS) in the workplace. Results: The monitoring revealed that the concentration of VOCs and metals generated during the 3D printing process was low. However, it also revealed that within the 3D printing area, the highest concentration of total volatile organic compounds(TVOC) was 4,164 ppb at the vat photopolymerization 3D printing workplace, and the lowest was 148 ppb at the material extrusion 3D printing workplace. For the metals monitoring, chromium, which, is carcinogenic for humans, was detected in the workplace. As a characteristic of the particles, nano-sized particles were also found during the monitoring, but most of them were agglomerated with large and small particles. Conclusions: Based on the monitoring conducted at the commercial 3D printing operation, the results revealed that the concentration of VOCs and metals in the workplace were within Korea's occupational exposure limits. However, due to the emission of nano-sized particles during 3D printing operations, it was recommended that the exposure to VOCs and metals in the workplace should be minimized out of concern for workers' health. It was also shown that the characteristics of particles emitted from 3D printing operations may spread widely within an indoor workplace.