Effect of friction coefficient on the mixed lubrication model of rotary lip seals

2019 ◽  
Vol 234 (11) ◽  
pp. 1746-1754
Author(s):  
Bingqi Jiang ◽  
Xing Huang ◽  
Fei Guo ◽  
Xiaohong Jia ◽  
Yuming Wang
Keyword(s):  
Numerical Calculation ◽  
Friction Coefficient ◽  
Boundary Lubrication ◽  
Dry Friction ◽  
Friction Torque ◽  
Mixed Lubrication ◽  
Test Method ◽  
Boundary Lubrication Friction ◽  
Pumping Rate ◽  
Lip Seals

This study is devoted to the effect of different coefficients on the calculation results of the rotary lip seal mixed lubrication model. It was proved by experiments that the dry friction coefficient used in the previous models was quite different from the boundary lubrication friction coefficient, which was theoretically more accurate. The pumping rate, friction torque, pressure distribution, and oil film thickness were calculated using both the dry friction coefficient and the boundary lubrication coefficient and the results were quite different. A friction coefficient test method under boundary lubrication condition for numerical simulation of rotary lip seals and an improved method for numerical calculation using the boundary lubrication coefficient instead of the dry friction coefficient were proposed. It was verified that the accuracy of numerical calculation can be improved, and the calculation result was closer to the actual working state.

Prediction of Wear Rate Dispersion in Mixed Lubrication

2005 ◽  
Author(s):  
F. Robbe-Valloire ◽  
R. Progri ◽  
B. Paffoni ◽  
R. Gras
Keyword(s):  
Friction Coefficient ◽  
Wear Rate ◽  
Boundary Lubrication ◽  
Mixed Lubrication ◽  
Tribological Behaviour ◽  
Low Friction ◽  
Local Boundary ◽  
Physico Chemical ◽  
Lubricant Films ◽  
Second Category

Mixed lubrication is usually related to the partition of contacts, and these latter may be divided into two categories. The first includes all asperities working in thin lubricated film (physico-chemical film) conditions. This situation corresponds to local boundary lubrication and is characterised by a local friction coefficient around 0.1. The second category contains all other asperity types. Due to the existence of a thick lubricant films asperities belonging to the second category exhibit a low friction coefficient. The global tribological behaviour for a given contact, however, is function of both categories, since it involves asperities from both categories.

Soft Elastohydrodynamic Analysis of Radial Lip Seals With Deterministic Microasperities on the Shaft

2007 ◽  
Vol 129 (4) ◽  
pp. 851-859 ◽  
Author(s):  
Philip C. Hadinata ◽  
Lyndon Scott Stephens
Keyword(s):  
Friction Coefficient ◽  
Load Capacity ◽  
Asperity Height ◽  
Pumping Rate ◽  
Simultaneous Reduction ◽  
Lip Seal ◽  
Lip Seals ◽  
Lubrication Characteristics ◽  
Triangular Design ◽  
Reverse Pumping

A numerical analysis is conducted to investigate the elastohydrodynamic effect of deterministic microasperities on the shaft of a lip seal. Various geometries of microasperities (triangular, square, hexagonal, and circular) are put into a 100×100μm2 unit cell and are investigated using Reynolds equation. For each shape, the area fraction of the microasperity is varied between 0.2 and 0.8, and the asperity height is varied between 0.3μm and 5μm. The calculation for load capacity and friction coefficient indicates that there are values for asperity height, where the load capacity and friction coefficient are optimized. These optimum heights were reached at 1–3μm. Although the lip seal surface is considered to be smooth, reverse pumping can still be obtained using an oriented triangular design. The Couette flow rate for this asperity showed lubricant is reverted back toward the seal side 2.6 times more than using a conventional lip seal. The addition of microasperities to the shaft surface shows significant improvement in lubrication characteristics for the lip seal in the form of a simultaneous reduction in friction coefficient and increase in the reverse pumping rate.

Influence of Additives in Synthetic Oils on Radial Lip Seals

2011 ◽  
Author(s):  
Mathias Klaiber ◽  
Werner Haas
Keyword(s):  
Friction Torque ◽  
Operating Conditions ◽  
Functional Tests ◽  
Dynamic Tests ◽  
Pumping Rate ◽  
Base Oil ◽  
Lip Seal ◽  
Lip Seals ◽  
Elastomeric Materials ◽  
Points Of View

This project has been initiated in order to get a general basic understanding about the influence of additives onto elastomeric lip seal systems. It is necessary to determine the behavior with single additive base oil compounds. Two different synthetic base oils, Polyglycol (PG) and Polyalphaolefin (PAO), are used. Thus 19 different single additive base oil compounds have been reviewed. Two different elastomeric materials NBR and FPM have been taken for all the tests. In several dynamic tests the influences on the sealing systems have been investigated. These included tests for 24 hours to measure the friction torque and tests for 10 hours to measure the pumping rate. Furthermore, the operating conditions during 96 hours functional tests have been determined. A concluding view onto the compatibility, respectively the incompatibility, of the additives in these different points of view will be given.

Soft elastohydrodynamic analysis of rotary lip seals

2010 ◽  
Vol 224 (12) ◽  
pp. 2637-2647 ◽  
Author(s):  
R F Salant
Keyword(s):  
Film Thickness ◽  
Thermal Effects ◽  
Mixed Lubrication ◽  
Extensive Literature ◽  
Physical Processes ◽  
Pumping Rate ◽  
Capillary Effects ◽  
Lip Seals ◽  
Statistical Approaches ◽  
Reverse Pumping

The extensive literature on the elastohydrodynamic analysis of rotary lip seals is reviewed. Models that predict quantities such as film thickness and reverse pumping rate and that elucidate the physical processes governing the behaviour of rotary lip seals are described. Thermal effects, mixed lubrication, capillary effects, transients, viscoelasticity, statistical approaches, and so-called hydrodynamic seals are discussed.

scholarly journals The Impact of Heat Treatment on the Behavior of a Hot-Dip Zinc Coating Applied to Steel During Dry Friction

Materials ◽  
2021 ◽  
Vol 14 (3) ◽  
pp. 660
Author(s):  
Dariusz Jędrzejczyk ◽  
Elżbieta Szatkowska
Keyword(s):  
Heat Treatment ◽  
Wear Resistance ◽  
Friction Coefficient ◽  
Dry Friction ◽  
Zinc Coating ◽  
Pin On Disc ◽  
The One ◽  
The Impact ◽  
Coating Hardness ◽  
Anticorrosion Properties

The analyzed topic refers to the wear resistance and friction coefficient changes resulting from heat treatment (HT) of a hot-dip zinc coating deposited on steel. The aim of research was to evaluate the coating behavior during dry friction after HT as a result of microstructure changes and increase the coating hardness. The HT parameters should be determined by taking into consideration, on the one hand, coating wear resistance and, on the other hand, its anticorrosion properties. A hot-dip zinc coating was deposited in industrial conditions (according EN ISO 10684) on disc-shaped samples and the chosen bolts. The achieved results were assessed on the basis of tribological tests (T11 pin-on-disc tester, Schatz®Analyse device, Sindelfingen, Germany), microscopic observations (with the use of optical and scanning microscopy), EDS (point and linear) analysis, and microhardness measurements. It is proved that properly applied HT of a hot-dip zinc coating results in changes in the coating’s microstructure, hardness, friction coefficient, and wear resistance.

scholarly journals Comparison Between the Action of Nano-Oxides and Conventional EP Additives in Boundary Lubrication

Lubricants ◽  
2020 ◽  
Vol 8 (5) ◽  
pp. 54
Author(s):  
Valdicleide Silva Mello ◽  
Marinalva Ferreira Trajano ◽  
Ana Emilia Diniz Silva Guedes ◽  
Salete Martins Alves
Keyword(s):  
Friction Coefficient ◽  
Boundary Lubrication ◽  
Friction And Wear ◽  
Film Formation ◽  
Environmental Issues ◽  
Protective Film ◽  
Extreme Pressure ◽  
Extreme Pressure Additives ◽  
Environmental Requirements ◽  
Lubrication Conditions

Additives are essential in lubricant development, improving their performance by the formation of a protective film, thus reducing friction and wear. Some such additives are extreme pressure additives. However, due to environmental issues, their use has been questioned because their composition includes sulfur, chlorine, and phosphorus. Nanoparticles have been demonstrated to be a suitable substitute for those additives. This paper aims to make a comparison of the tribological performance of conventional EP additives and oxides nanoparticles (copper and zinc) under boundary lubrication conditions. The additives (nanoparticles, ZDDP, and sulfur) were added to mineral and synthetic oils. The lubricant tribological properties were analyzed in the tribometer HFRR (high frequency reciprocating rig), and during the test, the friction coefficient and percentual of film formation were measured. The wear was analyzed by scanning electron microscopy. The results showed that the conventional EP additives have a good performance owing to their anti-wear and small friction coefficient in both lubricant bases. The oxides nanoparticles, when used as additives, can reduce the friction more effectively than conventional additives, and displayed similar behavior to the extreme pressure additives. Thus, the oxide nanoparticles are more environmentally suitable, and they can replace EP additives adapting the lubricant to current environmental requirements.

Friction and Wear Behaviors of Solid Lubricants/Polyimide Composites in Liquid Mediums

2010 ◽  
Vol 654-656 ◽  
pp. 2763-2766 ◽  
Author(s):  
Li Wen Mu ◽  
Xin Feng ◽  
Yi Jun Shi ◽  
Huai Yuan Wang ◽  
Xiao Hua Lu
Keyword(s):  
Friction Coefficient ◽  
Wear Rate ◽  
Tribological Properties ◽  
Alkaline Solution ◽  
Dry Friction ◽  
Friction And Wear ◽  
Solid Lubricants ◽  
Polyimide Composites ◽  
Inorganic Fillers ◽  
Ptfe Composites

The tribological properties of polyimide (PI) composites reinforced with graphite or MoS2 sliding in liquid alkali and water as well as dry friction were investigated using a ring-on-ring tester. The results show that the friction coefficient (μ) and wear rate (W) for both graphite/PI and MoS2/PI composites in different liquid mediums are μdry>μwater >μalkali and Wwater>Wdry >Walkali. Results also indicate that the friction coefficient and wear rate of the PI composites filled with different solid lubricants are μMoS2 >μgraphite and W MoS2 >Wgraphite in different liquid mediums. In addition, the hydrophobic inorganic fillers are fit for the reinforcement of polymer-based composites sliding in liquid mediums. It is also concluded from the authors’ work that the wear rate and friction coefficient of polymer-based (such as PI, PTFE) composites in the alkali lubricated conditions is lowest among all the friction conditions. This may be attributed to the ionic hydration in the alkaline solution.

The Relation Between the Friction of Lubricated Rough Surfaces and Apparent Normal Pressure

1989 ◽  
Vol 111 (2) ◽  
pp. 260-264 ◽  
Author(s):  
P. Lacey ◽  
A. A. Torrance ◽  
J. A. Fitzpatrick
Keyword(s):  
Surface Roughness ◽  
Friction Coefficient ◽  
Boundary Lubrication ◽  
Slip Line ◽  
Field Model ◽  
Rough Surfaces ◽  
Normal Pressure ◽  
Line Field ◽  
Slip Line Field ◽  
Asperity Contacts

Most previous studies of boundary lubrication have ignored the contribution of surface roughness to friction. However, recent work by Moalic et al. (1987) has shown that when asperity contacts can be modelled by a slip line field, there is a precise relation between the friction coefficient and the asperity slope. Here, it is shown that there is also a relation between the friction coefficient and the normal pressure for rough surfaces which can be predicted from a development of the slip line field model.

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