• Title/Summary/Keyword: Part Shrinkage

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Design of Injection Molding Process Factors Blower Fan using the Taguchi Method (다구찌법을 이용한 송풍팬 사출공정인자 설계)

  • Kim, Kyeong-Hwan;Choi, Jong-Yeun
    • Journal of the Korean Society of Manufacturing Process Engineers
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    • v.11 no.3
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    • pp.92-97
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    • 2012
  • Injection mold is a manufacturing process used to produce parts of complicated shape at a low cost. Many factors affect the quality of injection molded part during injection molding process. A study on the optimization of injection mold is progressed by using a simulation software like Moldflow. Filling, packing and cooling phases of injection molding processes are analyzed according to the mold design considering the shrinkage of molded part, the degree of filling rate and the wearing of a mold. Taguchi method is applied to analyze the significance of processing parameter and the dynamic characteristics according to the variation of processing parameters. From the results, the mold temperature and packing pressure influenced the shrinkage of injection molded part.

A STUDY OF WARPAGE IN ONE WAY LONG PARTS (한 방향으로 긴 제품에 대한 변형연구)

  • Kim, Jong-Kab;Cho, Chae-Sung;Park, Sang-Deuck
    • Proceedings of the KSME Conference
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    • 2000.04a
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    • pp.741-744
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    • 2000
  • In general there occur warpage in one way long part. Warpage is caused by differential shrinkage-Orientation Effect, Volumetric Shrinkage Effect, Differential Cooling Effect -over the part. Deco-Top is located at the top of 29"TV set and it's shape is one way long$(626{\times}130mm)$. Material is used transparency ABS resin. So we can't design ribs in this part. And we use film gate to avoid weld line. In these reasons we must develop no ribs and no warpage product. In this study we use MOLDFLOW's software-MF/FLOW, MF/COOL, MF/WARP. Using MF/FLOW, set the flow balance and gate positioning. And we can set cooling channel layout and the optimum processing condition through MF/COOL and MF/WARP. In result we reduced trials and obtained good product.

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Optimization of Injection Molding of Bobbin Part based on CAE (CAE를 이용한 보빈 성형품의 사출성형 최적화)

  • Kwon, Y.S.;Cho, Y.S.;Kim, B.G.;Min, B.H.;Jeong, Y.D.
    • Journal of Power System Engineering
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    • v.6 no.2
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    • pp.68-72
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    • 2002
  • Design of experiment was applied to analyze the shrinkage characteristics of the bobbin molded by injection molding. Among lots of design and processing conditions, the thickness of a bobbin and cooling conditions of a mold were considered. The temperature difference between top and bottom parts of the bobbin was considered as the objective to minimize the shrinkage of a bobbin. Optimal thickness of a bobbin was 2.0mm at the part of body and 1.5mm at the part of wing, respectively. Optimal cooling conditions such as cooling time and coolant inlet temperature were 12 second and $12^{\circ}C$, respectively.

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Experimental Investigation on the Distortion Error induced by Shrinkage in Sterolithography Process (광조형 공정 시 수축에 의한 변형 오차의 실험적 고찰)

  • Kim, Gi-Dae;Oh, Young-Tak
    • Transactions of the Korean Society of Machine Tool Engineers
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    • v.14 no.6
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    • pp.61-67
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    • 2005
  • During stereolithography processes, one of the main sources of dimensional error of prototype is the distortion effect owing to the shrinkage of resin. In this study, the effects of dimension of specimen, such as length, width, and thickness, on the curl distortion is examined. During the SL processes, the variation of curl distortion ewer is measured according to the number of layers, Through this study, it is verified that there is a big difference of the distortion error in both direction and magnitude between before and after the supports are removed. It Is also observed that end profile of the test part and the upper side around the border are also distorted due to the shrinkage of the resin.

Life Experiences of Middle School Students from Broken Homes (결손가정 중학생의 생활경험)

  • Choe, Gee-Hyun;Chung, Yeon-Kang;Yeoum, Soon-Gyo
    • Journal of the Korean Society of School Health
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    • v.10 no.2
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    • pp.271-283
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    • 1997
  • This study is designed for the school health education, contributing experience of life from middle school students from broken homes by describing specifically what they go through. And on this basis this study works out a grounded theory on the experience of life for middle school students from broken homes. The data was collected through a series of interviews with nine subjects singled out at each stage of research. With the permission of the subjects, the interviews were recorded and transcribed. The interviews lasted from 30 minutes up to one hour and 20 minutes. The in-depth interviewing methods and observations was used for data collection. The data was analyzed in the framework of grounded theory as mapped out by Strauss & Corbin (1990). By analyzing the materials eighty-three concepts were extracted, and they were united into 21 subordinate categories through the course of analysis. These were classified into nine precedence categories. The core category was found to be the adaptation of 'Wichookdem" or "Shrinkage". "Shrinkage" widows experienced was showed as the results "Self-reliance" and "Overcoming" through the course of generation and reaction, confrontation, and adaptation. According to the analysis findings of materials, the central phenomenon was showed as "shrinkage", the causal condition as "surprise", "Darkness", "Grudge", "Desolate", "Empty". The veins as presence of those around people and existence of support, and the meditate situation as self-support. For the strategy in solving "shrinkage", preparations of countermeasure and self-reinforcement were showed. And self-reliance and overcoming were the results. Through the contrast to the cases of ground materials, relation statements as follows were induced; (1) The weaker the suffering is, the weaker the "shrinkage" tends to be. (2) The stronger the suffering is, the stronger the "shrinkage" tends to be. (3) The more frequent and serious the suffering, the stronger the "shrinkage" tend to be. (4) The more infrequent and not serious the suffering is, the weaker the "shrinkage" tends to be. (5) The weaker the "shrinkage" is, the more self-control1ed the responses tends to be. (6) The stronger the "shrinkage" is, the more impulsive the responses tends to be. (7) The more satisfying the support is, the more self-controlled the responses to the "shrinkage" tends to be. (8) The more dissatisfying the support is, the more impulsive the responses to the "shrinkage" tends to be. (9) The more concrete the type of support is, the more self-controlled the responses to the "shrinkage" tends to be. (10) The more superficial the type of support is, the more impulsive the responses to the "shrinkage" tends to be. (11) The more self-controlled the responses are, the more self-reliant the subjects tends to be. (12) The more impulsive the responses are, the more conflict and wandering the subjects tends to be. (13) Whether the responses to the "shrinkage" express themselves in self-control or an impulse, it will be resulted in the form of either tension or pain. The following two were confirmed on the basis of repetitive relations; (1) If a subject's suffering is weak, infrequent and not serious, the "shrinkage" is weak. Also the subject's support is highly satisfying, and the support type is concrete. The responses to the "shrinkage" result in self-control which consequence is self-reliance with part. of it resulting in tension and pain. (2) If a subject's suffering is strong, frequent and serious, the "shrinkage" is strong. Also the subject's support is dissatisfying, and the support type is superficial. The responses to the "shrinkage" result in an impulsion whose consequence is wandering with part of it resulting in tension and pain. Through the results in this study, the following is to be suggested; O This research is basically aimed at analyzing the experience of the middle school students living in broken homes, for the more inclusive approach, the study for them is made systematically according to the type of their problems.

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Shrinkage Characteristics of 50MPa High-strength Concrete with Compositions of Cementitious Materials (결합재 구성에 따른 50MPa급 고강도 콘크리트의 수축 변형 특성)

  • Jung, Hyung-Chul;Min, Kyung-Hwan;Yang, Jun-Mo;Yoon, Young-Soo
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.13 no.3 s.55
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    • pp.93-100
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    • 2009
  • This study forms part of a research project that was carried out on the development and application of high-strength concrete for large underground spaces. In order to develop 50MPa high-strength concrete, eight optimal mixtures with different portions of fly ash and ground granulated blast furnace slag were selected. For assessments of shrinkage characteristics, free shrinkage tests with prismatic specimens and shrinkage crack tests were performed. The compressive strength was more than 30MPa at 7days, and stable design strength was acquired at 28days. High-strength concrete containing blast furnace slag shows large autogenous shrinkage, while large shrinkage deformations and cracks will occur when mixtures are replaced with large volumes of cementitious materials. Hence, for these high-strength concrete mixtures, the curing conditions of initial ages that affect the reaction of hydration and drying effects need to be checked.

Hydration of Expansive Materials with CSA-System (CSA계 팽창재료의 수화특성)

  • 정성철;송명신;이경희;한천구
    • Journal of the Korea Concrete Institute
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    • v.14 no.5
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    • pp.631-637
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    • 2002
  • This paper deals with hydration properties of the OPC with CSA-system expansive materials. In OPC using CSA, that was formed monosulfate for the main part. but In OPCs using CSA and gypsum, using CSA and gypsum and lime, that were formed ettringite for the main part. On the shrinkage ratio, the former is larger than the latter And CSA-system with gypsum and lime is smallest of all systems. According to dimension of shrinkage ratios are as follows; OPC using CSA only> OPC only> OPC using CSA and gypsum> OPC using CSA, gypsum and lime. And "R"s are 0.32, 0.37, 0.8, 0.8, 0.8 each others. In OPC with CSA-system expansive materials, we know that expansive properties were depend upon the value of "R". "R" means supplying quantities about demanding quantities for ettringite. In the case of expansive materials with CSA-system and lime, it is to be rich Ca(OH)$_2$ in the solution. so, it is formed small ettringite as the needle shapes. they are contribute to expansive.

Correlation between UV-dose and Shrinkage amounts of Post-curing Process for Precise Fabrication of Dental Model using DLP 3D Printer (DLP 공정을 이용한 정밀 치아모델 제작에서 UV 조사량과 후경화 수축률의 상관관계 분석)

  • Shin, Dong-Hun;Park, Young-Min;Park, Sang-Hu
    • Journal of the Korean Society of Manufacturing Process Engineers
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    • v.17 no.2
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    • pp.47-53
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    • 2018
  • Nowadays, additive manufacturing (AM) technology is a promising process to fabricate complex shaped devices applied in medical and dental services. Among the AM processes, a DLP (digital light processing) type 3D printing process has some advantages, such as high precision, relatively low cost, etc. In this work, we propose a simple method to fabricate precise dental models using a DLP 3D printer. After 3D printing, a part is commonly post-cured using secondary UV-curing equipment for complete polymerization. However, some shrinkage occurs during the post-curing process, so we adaptively control the UV-exposure time on each layer for over- or under-curing to change the local shape-size of a part in the DLP process. From the results, the shrinkage amounts in the post-curing process vary due to the UV-dose in 3D printing. We believe that the proposed method can be utilized to fabricate dental models precisely, even with a change of the 3D CAD model.

A Study on Co-Firing of Multilayer Chip LC Filter by Control of Shrinkage (수축율 조절에 의한 적층 칩 LC Filter의 동시 소성에 관한 연구)

  • Kim, Kyung-Yong;Lee, Jong-Kyu;Kim, Wang-Sup;Choi, Hwan
    • Journal of the Korean Ceramic Society
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    • v.28 no.9
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    • pp.675-682
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    • 1991
  • Among many problems that need to be solved in the process of preparing multilayer chip LC filters, we studied the control of shrinkage in order to prevent the crack, warpage, and/or delamination which occurs at the interface between the inductance (L part) and the capacitance (C part). Shrinkage was controlled by compositions, powder size, calcining temperature and amount of organic binder. Capacitance sheet was prepared by mixing 65 wt% binder with the composition of 96 wt% TiO2 having an average particle size of 0.5 $\mu\textrm{m}$, 3 wt% CuO. After small amount of MnO2 and SiO2 added, it was calcined at 750$^{\circ}C$ for 2 hr. Inductance sheet was prepared by mixing 60 wt% binder with the composition of 49.5% mol% Fe2O3, 20.5 mol% ZnO, 20 mol% NiO and 10 mol% CuO which was calcined at 775$^{\circ}C$ for 2 hr. These sheets was laminated at 250 kg/$\textrm{cm}^2$, and cofired at 900$^{\circ}C$ for 2 hr to give rise to a multilayer chip LC filter without any warpage.

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Study on the Physical Property of PTT/Tencel/Cotton MVS Blended Yarn for High Emotional Garment (I) - Physical property of blended yarn according to yarn structure - (고감성 PTT/Tencel/Cotton MVS 혼방사 패션소재의 물성에 관한 연구 (I) - 사 구조에 따른 혼방사 물성 -)

  • Kim, Hyun Ah
    • Fashion & Textile Research Journal
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    • v.18 no.1
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    • pp.113-119
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    • 2016
  • The evolution of spinning technology was focused on improving productivity with good quality of yarns. More detail spinning technology according to mixing of various kinds of fibre materials on the air vortex spinning system is required for obtaining good quality yarns. This paper investigated the physical properties of air vortex yarns compared with ring and compact yarns using PTT/tencel/cotton fibres. It was observed that unevenness of air vortex yarns was higher than those of ring and compact yarns, which resulted in low tenacity and breaking strain of air vortex yarns. Initial modulus of air vortex yarns was higher than those of ring and compact yarns. Yarn imperfections of air vortex yarns such as thin, thick and nep were much more than those of ring and compact yarns. These poor yarn qualities of air vortex yarn were attributed to the fasciated yarn structure with parallel fibres in the core part of the air vortex yarn. However, yarn hairiness of air vortex yarns was less and shorter than those of ring and compact yarns. Thermal shrinkage of air vortex yarns were higher than that of ring yarns, which was caused by sensible thermal shrinkage of PTT fibres on the bulky yarn surface and core part of air vortex yarns.