Papers by Keyword: Scuffing

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Authors: Carmen Bujoreanu, Florin Breabăn
Abstract: Bearing condition monitoring confronts the most machine users. Diagnostic methods used to include bearing problems represent one of the most important challenges. The scuffing phenomenon initiation of the bearing elements produces an important increase in the vibration level and can be emphasized by the analysis of the bearing friction forces which are the most sensitive indicator of the bearing failure. Commonly used technique for damage detection is the vibration signature analysis that must be carefully utilized in conjunction with the friction torque monitoring through the strain gauges measurements. In order to detect the scuffing onset, the paper presents an experimental setup for the scuffing tests performed on a 7206 ball bearing. A virtual instrument monitoring the friction force respectively the braking torque was created. An accelerometer captures the signal from the bearing outer ring then it is processed using PCI-4451 National Instruments data acquisition board and LabVIEW soft.
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Authors: Jie Lin Xu, Zeng Xiong Peng, Nan Wang, Shan Lin Xu
Abstract: The scuffing of friction pair is a common phenomenon in conditions of high speed and pressure. It was researched on scuffing characteristics in this paper. By using UMT-3 friction and wear tester, the friction and wear characteristics of slipper pair material in hydraulic component were investigated, and the friction coeficient-speed curves in the different pressures were got, as well as the wear rate-speed curves. The worn surface morphology of pin specimen was photographed by SEM, and the formation mechanism of the worn surface was analyzed. The results suggested that: friction coefficient and wear rate would have a jump when the scuffing occurred, the friction and wear characteristics would be affected by the interaction of pressure (P) and speed (V) . The PV characteristic restricted the correlation between working pressure and speed.
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Authors: Bogdan Antoszewski
Abstract: This paper presents the results of experimental research on the impact assessment texture on scuffing resistance. The results showed that the texturing increases the resistance to scuffing. Above it has been shown that texture having a smaller surface energy and having a larger volume are more resistant to scuffing.
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Authors: D. Chasoglou, E.M. Pechlivani, F. Stergioudis
Abstract: The modification of the outer layer of Al-Si alloys doped with iron atoms was examined. The samples both were taken from automotive pistons and they also were prepared in the laboratory. In any case, they were used as basic raw materials for examination. It was found that the structure and properties of these alloys are very much dependent on the cooling rate, composition and heat treatment. The iron atoms are usually doped, in order to diminish and stabilize the thermal expansion coefficient of the alloys. However, this process makes the alloys to become harder and harder; thus leading the alloys to a degradation of their mechanical behavior at elevated temperatures. Optical Microscope observations, SEM analysis of the interactive surface layers and XRD measurements were performed on tested samples. At elevated temperatures a large homogenized zone extended to about 500 (μm) without an apparent distribution of the silicon dendrites or faceted crystals was formed. Moreover at the surface of the so called homogenized zone a layer of about 35 (μm) was formed inside of which iron atoms were migrated. This layer is mainly responsible for scuffing phenomena.
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Authors: Yeau Ren Jeng, Shen Jenn Hwang
Abstract: This paper presents an experimental investigation of the influence of scuffing conditions on two-roller test rig. The prediction of Scuffing load capability model for the gear oils containing molybdenum dithiocarbomate (MoDTC) was developed based on the response surface methodology. A good agreement between the predicted and actual scuffing resistance was observed within ±5% significance level.
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Authors: J. Zhang, B. A. Shaw
Abstract: The contact fatigue performance of two pairs of case carburised gears with either an as-ground or superfinished surface finish was studied. This comparison test was carried out using a back-to-back gear test rig. Test results showed that superfinished gears provided an enhanced contact fatigue resistance with only the development of minor scratches and light micropitting after running, while as-ground gears failed through a sequence of initial micropitting, progressive micropitting, macropitting and scuffing.
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Authors: Remigiusz Michalczewski, Marek Kalbarczyk, Waldemar Tuszynski, Marian Szczerek
Abstract: One of the main problems with the operation of spiral bevel gears is related to very severe conditions in the contact of the meshing teeth; therefore, lubrication is very difficult, which increases the risk of scuffing occurrence. One of the ways to achieve better scuffing resistance is by the deposition of a low-friction coating on the bevel gears teeth. Gear scuffing tests were performed using a bevel gear test rig designed and manufactured at ITeE-PIB. The authorial bevel gear scuffing test was performed. Specially designed, spiral bevel gears were used for testing. Two material combinations were tested: uncoated pinion - coated wheel and, for reference, both gears without coatings. The a-C:H:W (trade name WC/C) coating of DLC type was deposited on the wheel teeth. A mineral, automotive gear oil of API GL-5 performance level was used for lubrication. It is shown that the resistance to scuffing may be significantly improved when the a-C:H:W coating is deposited on the spiral bevel gear teeth.
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Authors: Won Sik Choi, Jae Hwan Son, Inh Lee, Eun Young Jin, Ju Ri Kwon, Young Moon Lee, Noritsugu Umehara
Abstract: The purpose of this study is to find out the tribological characteristics of the various lubricants in cold forging of helical gear, which is used in mobile auto-transmission. Five kinds of lubricant were used in this study, i.e. L1, L2, L3, L4 and L5. The pin-on-disk type of friction wear test system has been adopted here. The normal load of 20, 40, 60, 80 and 100N has been applied to the test specimen. The sliding velocities were 0.06, 0.10, 0.14, 0.18, 0.22, 0.26, 0.30 and 0.34m/s. Experimental results show that the friction coefficients of oils having higher kinematic viscosity such as L1, L2, L4 and L5 tend to increase gradually as the sliding velocity increases. The increasing rate of the friction coefficient is relatively high in lower sliding velocity range. However in case of L3 which has low kinematic viscosity the friction coefficient tends to decrease as the sliding velocity increases. The friction coefficients of Bondelube and Bondelite were 3 times higher than those of L1 and L5. The Stribeck curve indicates that L1, L2, L4 and L5 were in hydrodynamic lubrication condition and L3 was in boundary lubrication condition. SEM micrographs revealed that there were some scratch, adhesive wear, adhesion wear and scuffing on the worn surface.
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Authors: Seung Min Yeo, Emerson Escobar Nunez, Andreas A. Polycarpou
Abstract: With increasing importance of advanced coating materials for use in interacting parts of air-conditioning compressors, several commercially available polymer-based coatings (PTFE/ Pyrrolidone-1, 2, PTFE/MoS2-1, 2, Fluorocarbon, PEEK/PTFE and PEEK/Ceramic coatings) were tribologically evaluated. Friction and wear behavior of these coatings, deposited on gray cast iron were in-situ measured using a specialized pin-on-disk tribometer. The experiments were performed under compressor specific conditions, namely under oscillatory motion simulating piston-type compressor and unidirectional motion simulating swash plate-type compressor operation. Also, the tribological properties of newly developed ATSP-based coatings deposited on aluminum substrates were evaluated under ball-on-disk, unidirectional sliding experiments. Polymer-based coatings exhibited excellent frictional properties, while their wear resistance was also acceptable, even though lower compared to hard coatings. However, the wear debris generated at the interface acted as a third-body solid lubricant with a beneficial role in their overall performance. ATSP coatings blended with fluoroadditives showed superior frictional behavior than pure ATSP coatings, and their wear rate was extremely low compared to commercially available PTFE-based coatings.
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