• Title, Summary, Keyword: 금속 FDM

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Metallic FDM Process to Fabricate a Metallic Structure for a Small IoT Device (소형 IoT 용 금속 기구물 제작을 위한 금속 FDM 공정 연구)

  • Kang, In-Koo;Lee, Sun-Ho;Lee, Dong-Jin;Kim, Kun-Woo;Ahn, Il-Hyuk
    • Journal of The Korea Internet of Things Society
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    • v.6 no.4
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    • pp.21-26
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    • 2020
  • An autonomous driving system is based on the deep learning system built by big data which are obtained by various IoT sensors. The miniaturization and high performance of the IoT sensors are needed for diverse devices including the autonomous driving system. Specially, the miniaturization of the sensors leads to compel the miniaturization of the fixer structures. In the viewpoint of the miniaturization, metallic structure is a best solution to attach the small IoT sensors to the main body. However, it is hard to manufacture the small metallic structure with a conventional machining process or manufacturing cost greatly increases. As one of solutions for the problems, in this work, metallic FDM (Fused depositon modeling) based on metallic filament was proposed and the FDM process was investigated to fabricate the small metallic structure. Final part was obtained by the post-process that consists of debinding and sintering. In this work, the relationship between infill rate and the density of the part after the post-process was investigated. The investigation of the relationship is based on the fact that the infill rate and the density obtained from the post-processing is not same. It can be said that this work is a fundamental research to obtain the higher density of the printed part.

Analysis of the Effect of Casting Residual Stress on Durability by a Combination of Different Numerical Methods (이종해석 연계 기법을 통한 주조 잔류응력이 내구성에 미치는 영향 분석)

  • Cheon, Jinho;Park, Yongho;Park, Ikmin
    • Korean Journal of Metals and Materials
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    • v.49 no.6
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    • pp.468-473
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    • 2011
  • Determining the residual stress during casting processes is important for evaluating the mechanical properties and strength of materials and to optimize manufacturing conditions. In this study, we propose a field data interface procedure between FDM and FEM in a 3-dimensional space for analyzing the casting process and structural analysis. The casting process was analyzed using FDM and the data of the temperature distribution were converted into a format suitable for FEM analysis to calculate the thermal stress and safety factor by tightening force. The results of the coupled analysis between FDM and FEM showed that casting residual stress is an important factor in predicting life time and evaluating durability.

Analysis of Microsegregation in Fe-Cr-Ni Weld Metal (Fe-Cr-Ni강 용접금속부의 미세편석에 관한 해석)

  • 박준민;박종민;안상곤;이창희;윤의박
    • Journal of Welding and Joining
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    • v.16 no.5
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    • pp.56-66
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    • 1998
  • During solidification or welding of alloys, the solute redistribution brings out microsegregation. The microsegregation causes the formation of non-equilibrium second phases, shrinkage and porosity degrading mechanical/chemical properties Therefore, it has been required to predict microsegregation quantitatively. To predict the degree of microsegregation, more exact and appropriate computer simulation technique has been actively used during last two decades. To predict the degree of microsegregation in weld metal, an advanced two dimensional model was suggested. In the new model, both primary and secondary arm regions were defined for the analysis region. The growth in the primary arm regina was assumed to be a planar for effective calculation. Especially, for the growth of a secondary arm, a simple and effective mathematical function was established to show the growing pattern, the solute diffusion in the solid phase was calculated by finite difference method (FDM). The solid-liquid interface movement was considered to be in local equilibrium state. The experiments for welding of 310S stainless steel were carried out in order to examined the reasonability and feasibility of this model. The concentration profiles of the solute predicted by this model were compared with those obtained from experimental works.

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A study on the manufacture of dissimilar metal jewelry using 3D printer (3D printer를 이용한 이종금속 주얼리 제작에 관한 연구)

  • Lee, Jung-Soo;Cha, Kyung-Chul
    • Journal of the Korean Crystal Growth and Crystal Technology
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    • v.26 no.1
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    • pp.19-22
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    • 2016
  • In the late 1990's implementation of CAD/CAM systems in 3D printer has been led to many changes in the jewelry industry. Low cost 3D printer has been started advertising in the jewelry in 2009 after expiration of key patents of FDM scheme. Mass jewelry production process will vary in appliance with direct production process of 3D printer production line. The studies presented in this variation is the jewelry manufacturing process using a 3D Printer and the different metals with different colors were also produced for bonding the prototype jewelry. Increasing the possibilities of 3D printer through them, presents a variety of jewelry mass production methods.

A Study on the Propagation Characteristics in Double Metal Strip Waveguides (이중 금속선 곡선형 도파로에서의 전파특성에 관한 연구)

  • Lee, Sang-Jun;Kim, Sang-In;Song, Seok-Ho
    • Korean Journal of Optics and Photonics
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    • v.18 no.3
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    • pp.226-231
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    • 2007
  • In this paper, we analyze the characteristics of various curved waveguides composed of double metal strips using finite difference method (FDM). Our investigation reveals that the bending loss of the double metal strip waveguide can be improved with less degradation of the straight waveguide's propagation loss compared to the single metal strip structure. Optimization of the double metal strip waveguide structure has been conducted considering bending and propagation losses.

Modelling for the Flying and Cooling Behaviors of the Centrifugally Atomized Particles (원심분무 입자의 비산 및 냉각 모델링)

  • 김형섭
    • Journal of Korean Powder Metallurgy Institute
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    • v.3 no.1
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    • pp.25-32
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    • 1996
  • Flying and solidification behaviors of the particles manufactured by centrifugal atomization were investigated. Both models were solved by the explicit FDM. Flying calculation supported the experimental results that the finer particles flied shorter than coarser particles and that particles flied shorter for lower rotation velocity than for higher velocity. Cooling curve and dendrite arm spacing were predicted by use of heat transfer analysis.

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A Study on the Mechanical Properties of Additive Manufactured Polymer Materials (적층조형 폴리머 재료의 기계적 물성 연구)

  • Kim, Dongbum;Lee, In Hwan;Cho, Hae Yong
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.39 no.8
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    • pp.773-780
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    • 2015
  • Traditionally, additive manufacturing (AM) technology has been used to fabricate prototypes in the early development phase of a product. This technology is being applied to release manufacturing of a product because of its low cost and fast fabrication. AM technology is a process of joining materials to fabricate a product from the 3D CAD data in a layer-by-layer manner. The orientation of a layer during manufacturing can affect the mechanical properties of the product because of its anisotropy. In this paper, tensile testing of polymer-based specimens were built with a typical AM process (FDM, PolyJet and SLA) to study the mechanical properties of the AM materials. The ASTM D 638 tensile testing standard was followed for building the specimens. The mechanical properties of the specimens were determined on the basis of stress-strain curves formed by tensile tests. In addition, the fracture surfaces of the specimens were observed by SEM to analyze the results.

Reduction of Computing Time through FDM using Implicit Method and Latent Heat Treatment in Solidification Analysis (FDM에 의한 응고해석시 계산시간 단축을 위한 음적해법의 적용과 잠열처리방법)

  • Kim, Tae-Gyu;Choi, Jung-Kil;Hong, Jun-Pyo;Lee, Zin-Hyoung
    • Journal of Korea Foundry Society
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    • v.13 no.4
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    • pp.323-332
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    • 1993
  • An implicit finite difference formulation with three methods of latent heat treatment, such as equivalent specific heat method, temperature recovery method and enthalpy method, was applied to solidification analysis. The Neumann problem was solved to compare the numerical results with the exact solution. The implicit solutions with the equivalent specific heat method and the temperature recovery method were comparatively consistent with the Neumann exact solution for smaller time steps, but its error increased with increasing time step, especially in predicting the solidification beginning time. Although the computing time to solve energy equation using temperature recovery method was shorter than using enthalpy method, the method of releasing latent heat is not realistic and causes error. The implicit formulation of phase change problem requires enthalpy method to treat the release of latent heat reasonably. We have modified the enthalpy formulation in such a way that the enthalpy gradient term is not needed, and as a result of this modification, the computation stability and the computing time were improved.

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Effect of current waveform on drop transfer in pulsed gas metal arc welding (Pulsed GMAW 의 전류 파형이 금속이행에 미치는 영향)

  • Hammad, Muhammad A.;Yoo, Choong-D.
    • Proceedings of the KWS Conference
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    • pp.48-48
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    • 2009
  • Conventionally in pulsed gas metal arc welding (GMAW-P), drop transfer is analyzed with simplest square pulse waveform. While the pulse current is described by four parameters (peak current magnitude and time plus base current magnitude and time), it deviates the real pulse shape. Real pulse can be better idealized by the trapezoidal pulse waveform described by two additional parameters, i.e., current rise and fall rate (dI/dt). Power source response rate is described by these parameters. In this work, the effect of these parameters on drop transfer is predicted by the force displacement model (FDM). While peak current has significant effects on drop detachment, drop transfer is also influenced by the current rise rate. Predictions indicate that the current rise rate can have considerable effects on the size of the detached drop if other pulse parameters are kept constant. FDM is applied to determine peak time for one drop one pulse condition (ODOP) when rests of the pulse parameters are given. The predicted range of ODOP shows good agreement with experimental data.

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A Study on Development of High Strength Al-Zn Based Alloy for Die Casting II: Evaluation of Fluidity and Gravity Casting (고강도 Al-Zn기 다이캐스팅 합금개발에 관한 연구 II: 중력주조, 유동성평가)

  • Shin, Sang-Soo;Lim, Young-Hoon;Kim, Eok-Soo;Lim, Kyung-Mook
    • Korean Journal of Metals and Materials
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    • v.50 no.7
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    • pp.531-538
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    • 2012
  • In this study, we evaluated the fluidity of the Al-Zn based alloys which exhibit excellent mechanical properties. We conducted computer simulations of fluid flow using the results of DSC, DTA analysis and Java-based Materials Properties software (J. Mat. Pro). Such computer simulations were then compared with the results obtained from experimental observations. The computer simulation results and the experimental results were very similar in fluidity length. It was found that the fluidity length of Al-Zn alloys is improved by increasing the Zn content while decreasing the solidus temperature of an alloy. In addition, we elucidate the effect of Zn addition on variations in different mechanical properties and the microstructure characteristics of (Al-xZn3Cu0.4Si0.3Fe) x=20, 30, 40, and 45 wt% alloys fabricated by gravity casting.