• 제목/요약/키워드: Friction characteristics

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CMP 결과에 영향을 미치는 마찰 특성에 관한 연구 (Characteristics of Friction Affecting CMP Results)

  • 박범영;이현섭;김형재;서헌덕;김구연;정해도
    • 한국전기전자재료학회논문지
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    • 제17권10호
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    • pp.1041-1048
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    • 2004
  • Chemical mechanical polishing (CMP) process was studied in terms of tribology in this paper. CMP performed by the down force and the relative motion of pad and wafer with slurry is typically tribological system composed of friction, wear and lubrication. The piezoelectric quartz sensor for friction force measurement was installed and the friction force was detected during CMP process. Various friction signals were attained and analyzed with the kind of pad, abrasive and abrasive concentration. As a result of experiment, the lubrication regime is classified with ηv/p(η, v and p; the viscosity, relative velocity and pressure). The characteristics of friction and material removal mechanism is also different as a function of the kind of abrasive and the abrasive concentration in slurry. Especially, the material removal per unit distance is directly proportional to the friction force and the non~uniformity has relation to the coefficient of friction.

낙동강 모래와 건설재료간의 직접전단시험에 의한 마찰각 특성 (Characteristics of Friction Angles between the Nak-dong River Sand and Construction Materials by Direct Shear Test)

  • 김영수;김대만
    • 한국지반공학회논문집
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    • 제25권4호
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    • pp.105-112
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    • 2009
  • 본 연구에서는 낙동강 모래의 내부마찰각과 모래와 건설재료들과의 접촉면에서 발생되는 표면마찰각의 특성을 파악하기 위하여 모래의 상대밀도와 전단속도를 변화시켜 목재, 강재, 몰탈, 그리고 역청재와 일련의 직접전단시험을 실시하였다. 시험결과 모든 경우에서 모래의 내부마찰각이 건설재료와의 표면마찰각보다 항상 크게 나타났고, 전단속도가 빠를수록 마찰각이 조금 증가되었다. 모래의 간극비가 작아짐에 의한 조밀화에 따라 마찰각은 선형적으로 증가하였으며, 간극비와 상대밀도의 변화에 따라 마찰각을 산정할 수 있는 식을 제시하였다. 또한 건설재료의 표면거칠기는 표면마찰각에 있어 중요한 인자임을 알 수 있었다.

디스크 경도에 따른 소결마찰재와 내열강 디스크의 마찰·마모 특성 (Study of the Tribological Characteristics Based on the Hardness of the Brake Disk between the Sintered Metallic Friction Material and the Heat-resisting Steel Disks)

  • 나선주;박형철;김상호
    • Tribology and Lubricants
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    • 제31권2호
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    • pp.42-49
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    • 2015
  • Because of the growing need for high-speed transport options such as trains and aircraft, there is increasing demand for technology related to high-speed trains. Among them, braking systems are important in high-speed trains in terms of reliability. Especially, the disk brake system, in use in most high-speed trains, transforms kinetic energy into thermal energy and noise. Therefore, the material properties of both the friction materials and disks are expected to influence the tribological characteristics. In this paper, the tribological characteristics depend on the hardness of the brake disks between the Cu-based sintered metallic friction material and the heat-treated heat-resisting steel disks. A lab-scale dynamometer used to perform braking tests at a variety of braking speeds using dry conditions. The test results revealed that the hardness of the disks affects the friction coefficients, friction stabilities, and wear rates. Thus, the brake system using the heat-resisting steel disk requires proper heat-treatment. These differences are considered to be caused by the change in tribological mechanisms and the generation of an oxide layer on the friction surfaces. The oxide layers on the friction surfaces are confirmed to Fe2O3 by x-ray diffraction (XRD) and scanning electron microscope-energy dispersive spectroscopy (SEM-EDS) analysis.

엔진 크랭크샤프트 베어링에 대한 마찰 및 온도 특성에 대한 실험적 연구 (An Experimental Study of the Friction and Temperature characteristics of Engine Crankshaft Bearings)

  • 조명래;문회지;장인배;한동철
    • 한국윤활학회:학술대회논문집
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    • 한국윤활학회 1993년도 제18회 학술대회 초록집
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    • pp.57-62
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    • 1993
  • To increase the fuel economy, a reduction of friction loss is important in engines. Experimental investigations have been required for reducing the friction loss of crankshaft bearings. Hydraulic cylinder, and servo control ler system which modified the applied load, and test rig for the observation of the characteristics of engine crankshaft bearings were designed and fabricated. Experiment is performed. Friction torque, journal locus and circumferential temperature variations of crankshaft bearings were measured with appling load, revolution speed, and oil inlet temperature, etc.

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마찰용접을 이용한 대형선박 터보챠저용 이종 로타샤프트 개발 (Development of Large Rotor Shaft for Marine Turbo Charger Using Friction Welding with Dissimilar Materials)

  • 문광일;전종원;정호승;조종래;최성규
    • 한국정밀공학회지
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    • 제33권4호
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    • pp.257-264
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    • 2016
  • Solid state joining techniques are increasingly applied in a wide range of industrial applications. Friction welding is a solid state welding technique that is used to join similar or dissimilar materials. In this study, friction welding was applied to rotor shaft composed of a disk and a shaft. The disk and shaft were manufactured by hot forging and rolling, respectively. The aim of the study was to predict the structural characteristics during hot forging and friction welding process for rotor shaft of turbo charger. The structural characteristics were determined by heat input and heat affected zone (HAZ) during a short cycle time. Thus, transient FE analysis for hot forging and friction welding was based on heat transfer. The results were used to predict structural characteristics during hot forging and friction welding processes. The prototype of rotor shaft was manufactured by the result-based process parameters.

2차원 마찰모델을 이용한 구면무단변속기의 변속특성해석 (Analysis on the Shift Characteristics of Semi-Spherical CVT using 2-dimensional Friction Model)

  • 공진형;임원식;박영일;김정윤
    • 한국자동차공학회논문집
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    • 제16권4호
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    • pp.103-109
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    • 2008
  • Semi-spherical CVT(SS-CVT) is one of friction drives, which transmits power via the friction force between a spherical shaped variator and output disks. The variator varies the speed ratio of SS-CVT continuously as well as transmits input power into the output shaft. Therefore two friction forces are normally applied on the variator; one is the longitudinal friction force for power transmission and the other is the lateral for shifting. In order to investigate the dynamic behavior of SS-CVT, we introduced a numerical model of 2-dimensional friction force using a function of slip ratio and slip angle. And a dynamic model, which describes the shifting mechanism of SS-CVT, is developed through 3-dimensional vector analysis. Finally we presented numerical results of the shift characteristics focused on the transient behavior of the variator's slip ratio and slip angle. The numerical results also show the typical CVT shifting characteristics of SS-CVT and stable shifting behaviors of the variator.

초고강도강판의 성형성에 미치는 슬라이드 모션 제어와 마찰특성의 영향 (Effect of Slide Motion Control and Friction Characteristics on Formability of Ultra High Strength Steel)

  • 송재선;윤국태;허재영;박춘달;김용환
    • 소성∙가공
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    • 제27권2호
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    • pp.107-114
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    • 2018
  • Although the application of high strength steel is increasing to cope with the various updated regulations of automobiles, high strength steel sheets are difficult to formulate due to the high tensile strength and low elongation of those materials. In this study, the slide motion was controlled using a servo press in order to improve the formability of the process of manufacturing ultra-high strength steel of above 1.2GPa. Also, the friction characteristics of the slid motion were investigated through a high speed friction test. The slide motion was optimized by adjusting the number of steps, the rising start position and the rise height of the slide. At the same time, it is noted that the optimal slide motion increased the forming depth by about 40%. From the results of the high speed friction test, the application of the slide motion reduces friction resistance, thereby improving friction characteristics and improving formability.

FRP 선박 외판재의 연삭마모 특성에 관한 연구 (A study on abrasive wear characteristics of side plate of FRP ship)

  • 김병탁;고성위
    • 수산해양기술연구
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    • 제44권3호
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    • pp.250-256
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    • 2008
  • Generally the side plate materials of FRP ship are composed of glass fiber and unsaturated polyester resin composites(GFRP composites). In this study, the effect of applied load and sliding speed on friction and wear characteristics of these materials were investigated at ambient temperature by pin-on-disc friction test. The cumulative wear volume, friction coefficient and wear rate of these materials for SiC abrasive paper were determined experimentally. The cumulative wear volume showed a tendency to increase nonlinearly with increase of sliding distance and was dependent on applied load and sliding speed for these composites. The friction coefficient of GFRP composites was increased as applied load increased at same sliding speed in wear test. It was verified by SEM photograph of worn surface that major failure mechanisms were microfracture, deformation of resin, cutting and cracking.

냉각인발된 쾌삭강의 외경선삭시 칩-공구 마찰 및 전단 특성 (Chip-Tool Friction and Shear Characteristics of Cold Drawn Free Machining Steels in Turning)

  • 이영문;조삼규;최수준;송태성;박태준
    • 한국정밀공학회지
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    • 제16권12호
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    • pp.198-203
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    • 1999
  • In this study, chip-tool friction and shear characteristics of cold drawn free machining steels in turning were assessed. To do this, a newly developed equivalent oblique cutting model was adopted. And for comparison with those of free machining steels, chip-tool friction and shear characteristics of conventional carbon steels were also investigated. The Pb-S free machining steel shows superior machinability to others. In case of the Bi-S free machining steel, the shear stress and the specific friction energy are relatively lower than those of conventional carbon steels, but its shear strain is relatively high, so it does not show any remarkable improvement of machinability.

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쿨롱 마찰계수들의 통계적 특성을 고려한 지면과 갤러핑을 하는 4 족 로봇간 접촉 모델링 (Contact Modeling between the Ground and the Galloping Quadruped Robot Considering Statistical Characteristics of Coulomb Friction Coefficients)

  • 권성훈;박종현;유홍희
    • 대한기계학회:학술대회논문집
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    • 대한기계학회 2007년도 춘계학술대회A
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    • pp.826-830
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    • 2007
  • The effects of the statistical properties of the Coulomb friction coefficients on the dynamic responses of a galloping quadruped robot are investigated in this paper. In general, the Coulomb friction coefficients are assumed to be deterministic for a controller design to achieve required motion characteristics. However, the friction coefficients between the ground and the robot legs are not constant in reality. Therefore, statistical characteristics of the friction coefficients need to be considered for a multi-body modeling of the robot galloping on the ground. The effects of the statistical properties on the dynamic responses of the quadruped robots are investigated.

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