• Title, Summary, Keyword: Layer Removal Technique

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Prediction of Dimensional Instability Resulting from Layer Removal of an Internally Stressed Orthotropic Composite Cylinder

  • Shin, Shang-Hyon
    • Journal of Mechanical Science and Technology
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    • v.16 no.6
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    • pp.757-761
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    • 2002
  • When a layer of cylindrical composite component containing an axisymmetric residual stress state is removed from the inner or outer surface, the dimension of the remaining material changes to balance internal forces. Therefore, in order to machine cylindrical composite components within tolerances, it is important to know dimensional changes caused by residual stress redistribution in the body. In this study, analytical solutions for dimensional changes and the redistribution of residual stresses due to the layer removal from a residually stressed cylindrically orthotropic cylinder were developed. The cylinder was assumed to have axisymmetric radial, tangential and axial residual stresses. The result of this study is useful in cases where the initial residual stress distribution in the component has been measured by a non-destructive technique such as neutron diffraction with no information on the effect of layer removal operation on the dimensional changes.

Hydrogen Plasma와 Oxygen Plasma를 이용한 50 nm 텅스텐 패턴의 Oxidation 및 Reduction에 관한 연구

  • Kim, Jong-Gyu;Jo, Seong-Il;Nam, Seok-U;Min, Gyeong-Seok;Kim, Chan-Gyu;Yeom, Geun-Yeong
    • Proceedings of the Korean Vacuum Society Conference
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    • pp.288-288
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    • 2012
  • The oxidation characteristics of tungsten line pattern during the carbon-based mask layer removal process using oxygen plasmas and the reduction characteristics of the WOx layer formed on the tungsten line surface using hydrogen plasmas have been investigated for sub-50 nm patterning processes. The surface oxidation of tungsten line during the mask layer removal process could be minimized by using a low temperature ($300^{\circ}K$) plasma processing instead of a high temperature plasma processing for the removal of the carbon-based material. Using this technique, the thickness of WOx on the tungsten line could be decreased to 25% of WOx formed by the high temperature processing. The WOx layer could be also completely removed at the low temperature of $300^{\circ}K$ using a hydrogen plasma by supplying bias power to the tungsten substrate to provide an activation energy for the reduction. When this oxidation and reduction technique was applied to actual 40 nm-CD device processing, the complete removal of WOx formed on the sidewall of tungsten line could be observed.

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Determination of Residual-Stress Distribution in Engineering Plastics (공업용 플라스틱 성형품에 대한 잔류응력의 측정)

  • Kim, Chae-Hwan;Youn, Jae-Ryoun
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • pp.132-135
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    • 2006
  • Injection molding is a flexible production technique for the manufacturing of polymer products, but introduces residual stresses. Residual stresses in a structural material or component are those stresses which exist in the object without other external loads. The layer removal and hole drilling method are used for the measurement of residual stress in injection molded polystyrene part. The hole drilling method is potentially more flexible for determining residual stress in complex geometries and can be used as an adoptable technique for the measurement of residual stress in polymeric materials. Results obtained by experiments agree with each other.

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Smear layer removal by different chemical solutions used with or without ultrasonic activation after post preparation

  • Poletto, Daniel;Poletto, Ana Claudia;Cavalaro, Andressa;Machado, Ricardo;Cosme-Silva, Leopoldo;Garbelini, Cassia Cilene Dezan;Hoeppner, Marcio Grama
    • Restorative Dentistry and Endodontics
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    • v.42 no.4
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    • pp.324-331
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    • 2017
  • Objectives: This study evaluated smear layer removal by different chemical solutions used with or without ultrasonic activation after post preparation. Materials and Methods: Forty-five extracted uniradicular human mandibular premolars with single canals were treated endodontically. The cervical and middle thirds of the fillings were then removed, and the specimens were divided into 9 groups: G1, saline solution (NaCl); G2, 2.5% sodium hypochlorite (NaOCl); G3, 2% chlorhexidine (CHX); G4, 11.5% polyacrylic acid (PAA); G5, 17% ethylenediaminetetraacetic acid (EDTA). For the groups 6, 7, 8, and 9, the same solutions used in the groups 2, 3, 4, and 5 were used, respectively, but activated with ultrasonic activation. Afterwards, the roots were analyzed by a score considering the images obtained from a scanning electron microscope. Results: EDTA achieved the best performance compared with the other solutions evaluated regardless of the irrigation method (p < 0.05). Conclusions: Ultrasonic activation did not significantly influence smear layer removal.

Performance Evaluation of Ti-Al-N coated Endmill by Arc ton Plating (아크이온플레이팅에 의한 Ti-Al-N코팅 엔드밀의 성능평가)

  • 이상용;강명창;김정석;김광호
    • Proceedings of the Korean Society of Machine Tool Engineers Conference
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    • pp.251-254
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    • 2002
  • The technique of high speed machining is widely studied in machining field. In this study, TiAIN single-layered and TiAIN/TiN double-layered coatings were applied to end-mill by an arc ion plating technique. Their performances were comparatively studied about cutting force, tool wear, tool life and surface roughness of workpiece under high speed cutting conditions. The TiAIN single-layer coated tool showed higher wear-resistance due to its higher hardness, while the TiAIN/TiN double-layer coated tool showed better performance for high metal removal, i.e., high fled per tooth condition due to its higher toughness. The surface roughness of the workpiece was not influenced by the wear amount of coated tools.

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Prediction and Measurement of Residual Stresses in Injection Molded Parts

  • Kwon, Young-Il;Kang, Tae-Jin;Chung, Kwansoo;Youn, Jae Ryoun
    • Fibers and Polymers
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    • v.2 no.4
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    • pp.203-211
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    • 2001
  • Residual stresses were predicted by a flow analysis in the mold cavity and residual stress distribution in the injection molded product was measured. Flow field was analyzed by the hybrid FEM/FDM method, using the Hele Shaw approximation. The Modified Cross model was used to determine the dependence of the viscosity on the temperature and the shear rate. The specific volume of the polymer melt which varies with the pressure and temperature fields was calculated by the Tait\`s state equation. Flow analysis results such as pressure, temperature, and the location of the liquid-solid interface were used as the input of the stress analysis. In order to calculate more accurate gap-wise temperature field, a coordinate transformation technique was used. The residual stress distribution in the gap-wise temperature field, a coordinate transformation technique was used. The residual stress distribution in the gap-wise direction was predicted in two cases, the free quenching, under the assumption that the shrinkage of the injection molded product occurs within the mold cavity and that the solid polymer is elastic. Effects of the initial flow rate, packing pressure, and mold temperature on the residual stress distribution was discussed. Experimental results were also obtained by the layer removal method for molded polypropylene.

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On the Measurment of Residual Stresses in Aluminum Alloy Casting Parts (알루미늄 합금 주조 부품에 발생하는 잔류응력의 측정)

  • 김채환
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • pp.102-106
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    • 1999
  • One of the main causes of unwanted dimensional changes in precision metal mold casting parts is excessive and irregular residual stresses induced by temperature gradients and plastic deformation in the solidifying shell. Residual stresses can also cause stress cracking and lower the fatigue life and fracture strength of the casting parts,. In the present study aluminum alloy casting system with metal mold equipped with electrical heating elements and water cooling units was designed and the casting specimens were produced to quantify the effects of different cooling conditions on the development of residual stresses. the layer removal method was used to measure the biaxial residual stresses in casting specimens produced from the experiments. The experimental results agreed with Tien-Richmond's theoretical model for thermal stress development for the solidifying metal plate

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On the Measurement of Residual Stresses in Aluminum Alloy Parts Fabricated by Precision Metal Mold Casting (정밀금형 알루미늄 합금 주물에서의 잔류응력 측정에 관한 연구)

  • Kim, Chae-Hwan;Mun, Su-Dong;Gang, Sin-Il
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.23 no.11
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    • pp.2087-2095
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    • 1999
  • One of the main causes of unwanted dimensional changes in precision metal mold casting parts is excessive and irregular residual stresses induced by temperature gradients and plastic deformation in the solidifying shell. Residual stresses can also cause stress cracking, and lower the fatigue life and fracture strength of the casting parts. In the present study, aluminum alloy casting system with metal mold equipped with electrical heating elements and water cooling units was designed and the casting specimens were produced to quantify the effects of different cooling conditions on the development of residual stresses. The layer removal method was used to measure the biaxial residual stresses in casting specimens produced from the experiments. The experimental results agreed with Tien-Richmond's theoretical model for thermal stress development for the solidifying metal plate.

Estimation Curvature Change Due to Layer Removal in Strips with Uniaxial Residual Stress Fidlds (축방향의 잔류응력이 내재하는 STRIP의 층 가공에 따른 곡율변화)

  • 신상현
    • Journal of the Korean Society of Fisheries and Ocean Technology
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    • v.33 no.2
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    • pp.149-155
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    • 1997
  • 잔류응력을 측정하는 비파괴 방법중 Neutron diffraction technique의 발달로 인하여 기존의 X-ray diffraction technique에 비하여 잔류응력 측정가능 두께가 대부분의 물질에 있어서 훨씬 깊어졌다. 비파괴 방법으로 부품내의 잔류응력 분포가 측정되어진 경우, 부품의 가공시 잔류응력의 재분포로 인한 형상의 변화를 정량적으로 예측할 수 있는 방법에 대해 어떠한 경우도 논의된 바 없다. 본 연구에서는 축 방향의 잔류응력이 내재하는 strip의 층 가공시 일어나는 strip의 곡율변화를 정량적으로 예측할 수 있는 수식을 제시하였다. 간단히 컴퓨터 프로그램화 할 수 있는 수식을 전개하므로 써 현장에서 유용하게 이용할 수 있게 하였다.

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A Study on Residual Powder Removing Technique of Multi-Layered Graphene Based on Graphene One-Step Transfer Process (그래핀 원스텝 전사(Graphene One-Step Transfer) 공정 기반 다층 그래핀 잔여분말 제거 기술 연구)

  • Woo, Chae-young;Jo, Yeongsu;Hong, Soon-kyu;Lee, Hyung Woo
    • Journal of Korean Powder Metallurgy Institute
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    • v.26 no.1
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    • pp.11-15
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    • 2019
  • In this study, a method to remove residual powder on a multi-layered graphene and a new approach to transfer multi-layered graphene at once are studied. A graphene one-step transfer (GOST) method is conducted to minimize the residual powder comparison with a layer-by-layer transfer. Furthermore, a residual powder removing process is investigated to remove residual powder at the top of a multi-layered graphene. After residual powder is removed, the sheet resistance of graphene is decreased from 393 to 340 Ohm/sq in a four-layered graphene. In addition, transmittance slightly increases after residual powder is removed from the top of the multi-layered graphene. Optical and atomic-force microscopy images are used to analyze the graphene surface, and the Ra value is reduced from 5.2 to 3.7 nm following residual powder removal. Therefore, GOST and residual powder removal resolve the limited application of graphene electrodes due to residual powder.