• 제목/요약/키워드: Die & Mold Design Engineering

검색결과 404건 처리시간 0.019초

펨토초 레이저 유도 나노 및 마이크로 구조물을 활용한 금속 표면 기능성 제어 (Controlled Surface Functionalities of metals using Femtosecond Laser-induced Nano- and Micro-scale Surface Structures)

  • 박태훈;이효수;이해중;황택용
    • Design & Manufacturing
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    • 제17권2호
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    • pp.55-61
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    • 2023
  • With femtosecond (fs) laser pulse irradiation on metals, various types of nano- and micro-scale structures can be naturally induced at the surface through laser-matter interaction. Two notable structures are laser-induced periodic surface structures (LIPSSs) and cone/spike structures, which are known to significantly modify the optical and physical properties of metal surfaces. In this work, we irradiate fs laser pulses onto various types of metals, cold-rolled steel, pickled & oiled steel, Fe-18Cr-8Ni alloy, Zn-Mg-Al alloy coated steel, and pure Cu which can be useful for precise molding and imprinting processes, and adjust the morphological profiles of LIPSSs and cone/spike structures for clear structural coloration and a larger range of surface wettability control, respectively, by changing the fluence of laser and the speed of raster scan. The periods of LIPSSs on metals used in our experiments are nearly independent of laser fluence. Accordingly, the structural coloration of the surface with LIPSSs can be optimized with the morphological profile of LIPSSs, controlled only by the speed of the raster scan once the laser fluence is determined for each metal sample. However, different from LIPSSs, we demonstrate that the morphological profiles of the cone/spike structures, including their size, shape, and density, can be manipulated with both the laser fluence and the raster scan speed to increase a change in the contact angle. By injection molding and imprinting processes, it is expected that fs laser-induced surface structures on metals can be replicated to the plastic surfaces and potentially beneficial to control the optical and wetting properties of the surface of injection molded and imprinted products.

22MnB5 / 탄소섬유 강화 플라스틱으로 제작된 단면 보강 하이브리드 적층판의 강도 보강에 관한 연구 (A study on strength reinforcement of one-sided reinforced hybrid laminates made of 22MnB5 and carbon fiber reinforced plastics)

  • 이환주;전용준;김동언
    • Design & Manufacturing
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    • 제16권2호
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    • pp.1-6
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    • 2022
  • As environmental regulations are strengthened, automobile manufacturers continuously research lightweight structures based on carbon fiber reinforced plastic (CFRP). However, it is difficult to see the effect of strength reinforcement when using a single CFRP material. To improve this, a hybrid laminate in which CFRP is mixed with the existing body structural steel was proposed. In this paper, CFRP patch reinforcement is applied to each compression/tensile action surface of a 22MnB5 metal sheet, and it was evaluated through a 3-point bending experiment. Progressive failure was observed in similar deflection on bending deformation to each one-sided reinforced specimen. After progressive failure, the tensile reinforced specimen was confirmed to separate the damaged CFRP patch and 22MnB5 sheet from the center of the flexure. The compression reinforced specimen didn't separate that CFRP patch and 22MnB5, and the strength reinforcement behavior was confirmed. In the compression reinforced specimen, damaged CFRP patches were observed at the center of flexure during bending deformation. As a result of checking the specimen of the compression reinforcement specimen with an optical microscope, It is confirmed that the damaged CFRP patch and the reinforced CFRP patch overlapped, resulting in a concentrated load. Through the experimental results, the 22MnB5 strength reinforcement characteristics according to the reinforcement position of the CFRP patch were confirmed.

이중 쇼트 피닝에 의한 SCM822H 강의 무해화 균열 크기 평가 (Evaluation of Harmless Crack Size of SCM822H Steel by Double Shot Peening)

  • 최진우;윤서현;권영국;이금화;남기우
    • 한국산업융합학회 논문집
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    • 제26권6_2호
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    • pp.1011-1017
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    • 2023
  • In this study, the harmless crack size (ahml) by double shot peening (DSP) using shot balls with different diameters was evaluated on carburized, quenched-tempered SCM822H steel. The minimum crack size (aNDI) detectable by non-destructive inspection was also evaluated. The relationship between the crack size (a25,50) that reduces the fatigue limit by 25% and 50% and ahml was evaluated. The residual stress of DSP was greater in SP(0.6+0.08) than SP(0.8+0.08) and appeared deeper in the depth direction. In addition, the hardness below the surface appeared larger. The fatigue limit of DSP increased 2.07 times and 1.95 times compared to non-SP. All ahml of the DSP specimen was determined at the depth (a). The compressive residual stress distribution affects ahml, and the ahml of SP(0.6+0.08), which has a large compressive residual stress and a high fatigue limit, appeared large. ahml of SP(0.6+0.08) introduced deeper than the residual stress of SP(0.8+0.08) is larger in the range of As=1.0-0.3. Since the residual stress in the thickness direction has a greater effect on ahml than the residual stress at the surface, it is necessary to introduce it more deeply. The relation of ahml, a25,50, and aNDI were evaluated in the point for safety and reliability.

혈관모사 마이크로채널이 장착된 3D 종양 세포 배양 시스템의 제작 및 검증 연구 (Fabrication and validation study of a 3D tumor cell culture system equipped with bloodvessle-mimik micro-channel)

  • 박정연;고범석;김기영;이동목;윤길상
    • Design & Manufacturing
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    • 제15권2호
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    • pp.11-16
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    • 2021
  • Recently, three-dimensional (3D) cell culture systems, which are superior to conventional two-dimensional (2D) vascular systems that mimic the in vivo environment, are being actively studied to reproduce drug responses and cell differentiation in organisms. Conventional two-dimensional cell culture methods (scaffold-based and non-scaffold-based) have a limited cell growth rate because the culture cannot supply the culture medium as consistently as microvessels. To solve this problem, we would like to propose a 3D culture system with an environment similar to living cells by continuously supplying the culture medium to the bottom of the 3D cell support. The 3D culture system is a structure in which microvascular structures are combined under a scaffold (agar, collagen, etc.) where cells can settle and grow. First, we have manufactured molds for the formation of four types of microvessel-mimicking chips: width / height ①100 ㎛ / 100 ㎛, ②100 ㎛ / 50 ㎛, ③ 150 ㎛ / 100 ㎛, and ④ 200 ㎛ / 100 ㎛. By injection molding, four types of microfluidic chips were made with GPPS (general purpose polystyrene), and a 100㎛-thick PDMS (polydimethylsiloxane) film was attached to the top of each microfluidic chip. As a result of observing the flow of the culture medium in the microchannel, it was confirmed that when the aspect ratio (height/width) of the microchannel is 1.5 or more, the fluid flows from the inlet to the outlet without a backflow phenomenon. In addition, the culture efficiency experiments of colorectal cancer cells (SW490) were performed in a 3D culture system in which PDMS films with different pore diameters (1/25/45 ㎛) were combined on a microfluidic chip. As a result, it was found that the cell growth rate increased up to 1.3 times and the cell death rate decreased by 71% as a result of the 3D culture system having a hole membrane with a diameter of 10 ㎛ or more compared to the conventional commercial. Based on the results of this study, it is possible to expand and build various 3D cell culture systems that can maximize cell culture efficiency by cell type by adjusting the shape of the microchannel, the size of the film hole, and the flow rate of the inlet.