• Title/Summary/Keyword: Sliding wear

Search Result 720, Processing Time 0.031 seconds

Experimental Study on Friction Characteristics of Pb-free Pin Bushing for an Internal Combustion Engine (내연기관용 무연 핀부싱의 마찰특성에 관한 실험적 연구)

  • Kim, Chung-Kyun;Oh, Kyoung-Seok
    • Tribology and Lubricants
    • /
    • v.23 no.6
    • /
    • pp.306-311
    • /
    • 2007
  • This paper presents the friction characteristics of pb-fres pin bushing bearings for an automotive gasoline engine. The external load is 100 N to 600 N and the speed of the pin bushing bearing is 1000 rpm to 3000 rpm against the rubbing surfaces. And the contact modes of rubbing surfaces between a piston pin and a pb-free pin bushing specimen are a dry friction, an oil lubricated friction and a mixed friction that is starved by a lack of engine oil. Two influential factors of a contact rubbing modes and a material property are very important parameters on the tribological performance of a friction characteristic between a piston pin and a pb-free pin bushing. The experimental result shows that the pin bushing speed of 2000 rpm shows a typical oil film lubricated sliding contact mode in which means that as the applied load is increased, the friction loss is increasing. But other contact mode depending on the speed and the load may affect to the fiction coefficient without a regular and uniform trend. In summary, the oil lubricated rubbing surface definitely decreases a running-in period in short and increase oil film stiffness, and this may leads the reduction of a friction loss.

Dry Sliding Wear Behavior of Carbide-Particle-Reinforced 7075 Al Alloy Matrix Composites (탄화물(SiC, TiC, $B_4C$ ) 입자 강화 7075 Al 합금 기지 복합재료의 건식 미끄럼 마멸 거동)

  • 강석하;박형철;강신철;김용석
    • Proceedings of the Materials Research Society of Korea Conference
    • /
    • 2003.03a
    • /
    • pp.27-27
    • /
    • 2003
  • 무가압침투법으로 제조된 부피분율 10~24% SiC, TiC, B$_4$C 탄화물 입자강화 7075 Al 합금 기지 복합재료의 건식 미끄럼 마멸거동을 강화입자의 종류, 크기 및 부피 분율을 변수로 연구하였다. 미끄럼 마멸 시험은 pin-on-disk 형태의 마멸 시험기를 사용하여, AISI 52100 베어링강을 상대재로 상온 대기 중에서 실시되었다. 마멸특성의 분석과 마멸기구의 규명을 위하여 마멸면과 마멸단면을 SEM, EDS를 이용하여 분석하였다. 제조된 복합재료의 압축 시험을 통하여 측정된 항복강도와 가공경화지수는 서로 반비례하였고, 각 시편간의 경도 차는 크지 않았다. 마멸 시험결과, 크기 및 부피 분율이 7$\mu\textrm{m}$ !0%인 SiC 입자로 강화된 복합재료를 제외하고, 전체 복합재료 시편은 7075 Al 기지 합금에 비해 낮은 마멸 속도를 보였다. 10N 이하의 저하 중에서는 강화상의 종류와 상관없이 복합재료는 낮은 마멸 속도를 보였고, 25N 이상의 고하중에서는 TiC 입자강화 복합재료가 가장 낮은 마멸 속도를, SiC 입자강화 복합재료가 가장 높은 마멸 속도를 나타내었다. 강화 입자의 크기 및 부피 분율이 동일한 경우 SiC 입자로 강화된 복합재료가 가장 낮은 내마멸성을 나타내었다. 강화상의 크기 및 부피 분율이 증가함에 따라 미소 마멸에서 격렬 마멸로의 천이 하중이 증가하였다.

  • PDF

Tribological Properties of C-SiC Brake Discs with Surface Modifications (세라믹 디스크의 표면 개질에 따른 마찰 마모 특성)

  • Jang, Ho;Kim, Ki-Jung;Hwang, Hee-Jeong;Kim, Seong-Jin;Park, Hong-Sik
    • Tribology and Lubricants
    • /
    • v.24 no.4
    • /
    • pp.163-169
    • /
    • 2008
  • Tribological properties of ceramic brake discs were investigated using a commercial friction material. The discs were manufactured by liquid silicon infiltration (LSI) into a C-C preform. The disc surface was modified by two different methods, producing sliding surfaces with chopped carbon fibers and carbon felt. In addition, the composition of the surface was also changed. Friction characteristics of the discs were examined using a 1/5 scale dynamometer. Results showed that the type and composition of the disc surface significantly affected the level of braking effectiveness and high temperature brake performance. The discs with felt surfaces showed higher friction levels than those with chopped fiber surfaces and SiC tended to increase the friction level while C lowered the friction coefficient. The ceramic disc was more sensitive to the deceleration rate than gray iron, showing high speed sensitivity.

The Friction Characteristics of the Journal Bearing in the Refrigerant Compressor

  • Cho, Ihn Sung;Baek, Il Hyun;Oh, Seok Hyung;Jung, Jae Youn
    • KSTLE International Journal
    • /
    • v.1 no.2
    • /
    • pp.113-117
    • /
    • 2000
  • The rotary-vane compressor has become one of the most successful types of compressors because of its mechanical reliability, compactness, and adaptability to moderately high-speed operation in virtually an unlimited range of sizes. However recently, the depletion of the ozone layer due to the current refrigerant(R22) has been getting worse, and it is one of the world's pressing issues. In this paper, we will discuss the use of R410a in the compressor of a room air-conditioner as an alternative refrigerant and air-conditioning system to R22, since R410a has greater refrigerant characteristics than R22. Miniaturization of the rotary compressor for the new refrigerant and air-conditioning system is also possible, which reduces the prime cost of production, hence R410a is naturally a better refrigerant. But to apply the new HFC refrigerant system in refrigeration and air-conditioning systems, a significant redesign of the current refrigerant system is also required, because as the refrigeration changes, lubrication characteristics vary. Close attention must be paid to friction force and energy loss due to friction and wear at many sliding areas.

  • PDF

Tribology Research Trends in Chemical Mechanical Polishing (CMP) Process (화학기계적 연마(CMP) 공정에서의 트라이볼로지 연구 동향)

  • Lee, Hyunseop
    • Tribology and Lubricants
    • /
    • v.34 no.3
    • /
    • pp.115-122
    • /
    • 2018
  • Chemical mechanical polishing (CMP) is a hybrid processing method in which the surface of a wafer is planarized by chemical and mechanical material removal. Since mechanical material removal in CMP is caused by the rolling or sliding of abrasive particles, interfacial friction during processing greatly influences the CMP results. In this paper, the trend of tribology research on CMP process is discussed. First, various friction force monitoring methods are introduced, and three elements in the CMP tribo-system are defined based on the material removal mechanism of the CMP process. Tribological studies on the CMP process include studies of interfacial friction due to changes in consumables such as slurry and polishing pad, modeling of material removal rate using contact mechanics, and stick-slip friction and scratches. The real area of contact (RCA) between the polishing pad and wafer also has a significant influence on the polishing result in the CMP process, and many researchers have studied RCA control and prediction. Despite the fact that the CMP process is a hybrid process using chemical reactions and mechanical material removal, tribological studies to date have yet to clarify the effects of chemical reactions on interfacial friction. In addition, it is necessary to clarify the relationship between the interface friction phenomenon and physical surface defects in CMP, and the cause of their occurrence.

Optimization and Analysis of Output Pinion Design for Worm Gear Reducer (워엄기어 감속기의 출력피니언 최적설계와 해석)

  • Cho, Seonghyun;Kim, Hyeonkyeong;Kim, Dongseon;Zhen, Qin;Lyu, Sung-Ki
    • Journal of the Korean Society of Manufacturing Process Engineers
    • /
    • v.19 no.1
    • /
    • pp.108-113
    • /
    • 2020
  • Pinions are generally heavy and integrated with a shaft. Thus, fabricating a pinion is a material- and machining-intensive task characterized by low productivity. Contact of the output pinion with a sliding surface or a cloud contact causes loss of power because of friction. Consequently, the output pinion undergoes considerable wear and tear at its ends, which adversely affects the overall transmission efficiency of decelerators. To improve transmission efficiency and extend gear life, an optimum output pinion design is required. To this end, in this study, an output pinion for worm gear decelerators was designed and optimized by means of product verification through prototyping and performance evaluation to improve gear life and productivity. The optimized design was validated and subjected to structural analysis.

Tribological Failure Study of Manual Transmissions in Front Engine and Front Wheel Drive Vehicle (전륜구동 수동변속기에 대한 트라이볼로지적 고장사례 연구)

  • Kim, Chung-Kyun;Lee, Il-Kwon
    • Tribology and Lubricants
    • /
    • v.24 no.6
    • /
    • pp.285-290
    • /
    • 2008
  • The purpose of this paper is to present the case study of tribological failure analysis on the gear damages, oil leakage, and sealant sealing in a manual transmission of front engine and front wheel drive vehicle. The manual transmission is to change the speed range and direction of the engines depending on the driving conditions by friction driving forces with input and output gear system. The material property and surface roughness of the gears are strongly related to the gear noise and micro-vibration, oil leakage and wear, which may decrease the real contact area of the gear and the strength of the oil film thickness between the driving gear and driven one. The O-ring damage of speedometer driven gear and bad sealant sealing of oil pan may produce oil leakage through the contact surfaces, which cause the oil shortage and seizure on the sliding surfaces of the transaxle gears. In the failure case study, the proper repair working and good lubrication are very important for the long life of the transaxle without any tribological failures and oil leakage.

Study on the Frictional Properties of Nylons Synthesized by Varying Catalyst Content (촉매 함량 변화에 따라 합성된 나일론의 마찰 특성에 관한 연구)

  • Chung, Dae-Won;Kang, Suk-Choon
    • Polymer(Korea)
    • /
    • v.29 no.1
    • /
    • pp.14-18
    • /
    • 2005
  • Nylons were synthesized by anionic polymerization of ${\varepsilon}$--caprolactam while varying the content of catalyst. Polymerization rates, molecular weights, mechanical properities and frictional properties of the nylons were investigated. As the ratio of catalyst to initiator was increased up to 1.0%, the polymerization rate, conversion and molecular weight were found to increase, and mechanical properties except impact strength were improved. Frictional properties were affected mainly by tensile strength and hardness. According to the study on the friction coefficient, product of stress (P) and velocity (V), PV limit, and abrasive wear rate, nylon synthesized at 1.0% of the ratio of catalyst to initiator showed the best performance for sliding machine elements.

Development of Novel Composite Powder Friction Modifier for Improving Wheel-rail Adhesion in High-speed Train (고속열차 점착계수 향상을 위한 신규 복합재료 분말 마찰조절재 개발 및 점착력 특성 평가)

  • Oh, Min Chul;Ahn, Byungmin
    • Journal of Powder Materials
    • /
    • v.25 no.6
    • /
    • pp.501-506
    • /
    • 2018
  • With the recent remarkable improvements in the average speeds of contemporary trains, a necessity has arisen for the development of new friction modifiers to improve adhesion characteristics at the wheel-rail interface. The friction modifier must be designed to reduce slippage or sliding of the trains' wheels on the rails under conditions of rapid acceleration or braking without excessive rolling contact wear. In this study, a novel composite material consisting of metal, ceramic, and polymer is proposed as a friction modifier to improve adhesion between wheels and rails. A blend of Al-6Cu-0.5Mg metallic powder, $Al_2O_3$ ceramic powder, and Bakelite-based polymer in various weight-fractions is hot-pressed at $150^{\circ}C$ to form a bulk composite material. Variation in the adhesion coefficient is evaluated using a high-speed wheel-rail friction tester, with and without application of the composite friction modifier, under both dry and wet conditions. The effect of varying the weighting fractions of metal and ceramic friction powders is detailed in the paper.

CFD Analysis of Trap Effect of Groove in Lubricating Systems: Part II - Variation in Radius of Curvature of Groove Edge (그루브의 Trap 효과에 대한 CFD 해석: 제2부 - 그루브 모서리의 곡률반경 변화)

  • Hong, Sung-Ho
    • Tribology and Lubricants
    • /
    • v.36 no.6
    • /
    • pp.359-364
    • /
    • 2020
  • Numerical investigation of the groove trap effect with variation in the groove-edge radius of curvature is presented here. The trap effect is evaluated in a two-dimensional sliding bearing using computational fluid dynamics (CFD). This simulation is based on the discrete phase model (DPM) and standard k - ε turbulence model using commercial CFD software, FLUENT. The numerical results are evaluated by comparisons with streamlines and particle trajectories in the grooves. Grooves are applied to various lubrication systems to improve their lubrication characteristics, such as load carrying capacity increment, leakage reduction, frictional loss reduction, and preventing three-body abrasive wear due to trapping effect. This study investigates the grove trapping effect for various groove-edge radius of curvature values and Reynolds numbers. The particle is assumed to be made of steel, with a circular shape, and is injected as a single particle in various positions. One-way coupling is used in the DPM model because the single particle injection condition is applied. Further, the "reflect" condition is applied to the wall boundary and "escape" condition is used for the "pressure inlet" and "pressure outlet" boundaries. From the numerical results, the groove edge radius is found to influence the groove trap effect. Moreover, the groove trap effect is more effective when applying the groove edge radius.