scholarly journals Micro-Pitting and Wear Assessment of PAO vs Mineral-Based Engine Oil Operating under Mixed Lubrication Conditions: Effects of Lambda, Roughness Lay and Sliding Direction

Lubricants ◽  
2019 ◽  
Vol 7 (5) ◽  
pp. 42 ◽  
Author(s):  
Aleks Vrček ◽  
Tobias Hultqvist ◽  
Yannick Baubet ◽  
Marcus Björling ◽  
Pär Marklund ◽  
...  
Keyword(s):  
Bearing Steel ◽  
Mixed Lubrication ◽  
Operating Conditions ◽  
Engine Oil ◽  
Engine Oils ◽  
Rolling Contacts ◽  
Steel Surfaces ◽  
Wear Damage ◽  
Lubrication Conditions ◽  
Ball On Disc

Under certain operating conditions, rolling contacts have been shown to experience some challenges when lubricated with engine oils containing zinc dialkyldithophosphate (ZDDP) anti-wear additive. In order to better understand the main damage mechanisms during various operating conditions, further studies are needed. This article studies micro-pitting and wear damages of bearing steel surfaces under mixed lubrication conditions in a ball-on-disc setup, lubricated with different engine oils. Based on the results, micro-pitting and wear damage is shown to be highly case-dependent. In general, PAO-based engine oil tends to eliminate micro-pitting damage compared to mineral-based engine oil at less severe lubricating conditions. Moreover, a critical lambda was found for both oils, where the highest micro-pitting damage was observed.

Micro-pitting Damage of Bearing Steel Surfaces under Mixed Lubrication Conditions: Effects of Roughness, Hardness and ZDDP Additive

2019 ◽  
Vol 138 ◽  
pp. 239-249 ◽  
Author(s):  
Aleks Vrček ◽  
Tobias Hultqvist ◽  
Yannick Baubet ◽  
Pär Marklund ◽  
Roland Larsson
Keyword(s):  
Bearing Steel ◽  
Mixed Lubrication ◽  
Steel Surfaces ◽  
Lubrication Conditions

Aspects of thrust cone tribology: Part 1: Effects of slide to roll ratio on surface failure mechanisms in twin-disc tests

1998 ◽  
Vol 212 (1) ◽  
pp. 55-72 ◽  
Author(s):  
D. A. Kelly ◽  
C. G. Barnes ◽  
L. M. Rudd
Keyword(s):  
Plastic Deformation ◽  
Failure Mechanisms ◽  
Mineral Oil ◽  
Operating Conditions ◽  
Surface Failure ◽  
Contact Frequency ◽  
Steel Surfaces ◽  
Load Intensity ◽  
Frequency Variations ◽  
Lubrication Conditions

This paper describes mineral oil lubricated twin-disc tests with nominal point or line contact at rolling (mean surface) speeds in the range 3-23 m/s and slide-roll ratios in the range 15-80 per cent. The results identify a regime in the sliding/rolling speed domain in which failure of EN36A (750 DPN) and EN24U (350 DPN) is predominantly by scuffing preceded by running-in, which delays scuffing to relatively severe operating conditions. At speed combinations above the identified regime, the steels fail by scuffing in, or close to, mixed lubrication conditions with little or no running-in, so that the conventional failure criterion based on a film thickness to r.m.s. surface roughness value of three is appropriate. At speed combinations below the identified regime, load intensity becomes sufficient so that general plastic deformation intervenes before failure by scuffing can occur and a shakedown-based criterion becomes appropriate. Observations of contact frequency variations suggest that with steel surfaces at 650 and 750 DPN running-in is produced by rubbing of asperity tips and that with steel surfaces at 350 and 450 DPN it is produced by hydrodynamic ripple pressures. For the latter materials at low slide-roll ratios, macro- and micropitting are likely concomitants of plastic deformation.

scholarly journals Design of Laboratory Test Equipment for Automotive Oil Filters to Evaluate the Technical Life of Engine Oil

2021 ◽  
Vol 11 (2) ◽  
pp. 483
Author(s):  
Hujo Ľubomír ◽  
Jablonický Juraj ◽  
Markovič Jaromír ◽  
Tulík Juraj ◽  
Simikić Mirko ◽  
...  
Keyword(s):  
Laboratory Test ◽  
Operating Conditions ◽  
Test Equipment ◽  
Engine Oil ◽  
Laboratory Measurements ◽  
Laboratory Equipment ◽  
Engine Oils ◽  
Simultaneous Testing ◽  
Motor Oils ◽  
Filtration Capacity

The main aim of the article is to present the design of laboratory test equipment, which is appropriate for monitoring the efficiency of oil filters and the system for evaluating the technical life of engine oils in terms of possible extension of service intervals. The functionality of the designed laboratory test equipment for the filtration of motor oils was verified by a practical experiment with a verification measurement and assessment of the suitability of the hydraulic circuit elements and the designed sensing equipment. The laboratory equipment enables the testing of oil filters with different filtration capacity during simultaneous testing in two separate hydraulic circuits with differently contaminated engine oil, while it enables laboratory measurements to be performed while simulating operating conditions.

scholarly journals Assessment of the intensity of engine oil contamination during operation

2021 ◽  
Vol 2131 (3) ◽  
pp. 032061
Author(s):  
V Zhukov ◽  
O Melnik ◽  
E Khmelevskaya
Keyword(s):  
Internal Combustion Engines ◽  
Operating Time ◽  
Operating Conditions ◽  
Engine Oil ◽  
Oil Contamination ◽  
Engine Oils ◽  
Average Operating ◽  
Average Operating Time ◽  
Dispersing Ability ◽  
Physical And Chemical

Abstract The acceleration of internal combustion engines leads to an increase in thermal and mechanical loads on the most critical parts. To ensure the required resource indicators in conditions of increased loads, it is necessary to use high-quality lubricants, the requirements for the operational properties of which are also steadily increasing. In order to ensure the necessary physical and chemical characteristics of engine oils, additives are introduced into their composition, but during operation the quality of engine oil decreases, the reasons for this are both the destruction of additives, and the accumulation of dirt particles in the oil and the ingress of fuel and coolant into the oil. The conducted studies are devoted to determining the intensity of engine oil contamination under operating conditions in the Wärtsilä 6L20 engine lubrication system and the effectiveness of the dispersing additives contained in the oil. Samples of Petro Canada and TARO oils brands were used as prototypes at the beginning of the operational period, at the time of average operating time and at the time of oil change. The dispersing ability of the oil was determined by the method of assessing the oil stain. According to the results of the research, it is concluded that when the properties of the oil change as a result of contamination, their dispersing ability remains satisfactory. This result can serve as a justification for extending the service life of engine oil, provided that its properties are monitored during operation.

Half-frequency whirl of pistons in axial piston pumps and motors under mixed lubrication

2003 ◽  
Vol 217 (2) ◽  
pp. 93-102 ◽  
Author(s):  
K Tanaka ◽  
T Nakahara ◽  
K Kyogoku
Keyword(s):  
Mixed Lubrication ◽  
Operating Conditions ◽  
Axial Piston Pump ◽  
Piston Motion ◽  
Axial Piston Pumps ◽  
Supply Pressure ◽  
Oil Whirl ◽  
Lubrication Characteristics ◽  
Axial Piston ◽  
Lubrication Conditions

Dynamic lubrication characteristics between a piston and a cylinder in an axial piston pump and motor have been calculated under mixed-lubrication conditions. The calculated results have shown that half-frequency whirling of the piston occurs under some operating conditions and specifications such as low supply pressure, narrow clearance and long sealing length between the piston and the cylinder, in a manner similar to the oil whirl phenomenon in journal bearings. The whirl phenomenon has been confirmed by measurements of piston motion.

Tribological characterization of potential crankshaft bearing steels for roller bearing engines

2020 ◽  
pp. 135065012095778
Author(s):  
Aleks Vrček ◽  
Tobias Hultqvist ◽  
Tomas Johannesson ◽  
Pär Marklund ◽  
Roland Larsson
Keyword(s):  
Residual Stress ◽  
Combustion Engine ◽  
Roller Bearing ◽  
Surface Hardness ◽  
Bearing Steel ◽  
Engine Oil ◽  
Limiting Factor ◽  
Surface Fatigue ◽  
Bearing Steels ◽  
Wear Damage

A crankshaft roller bearing internal combustion engine (ICE) offers a five percent or more improvement in overall engine efficiency and, thereby, a reduction in a five percent of CO2 emissions, compared to a plain bearing supported crankshaft. Current forged crankshaft steels represent the limiting factor of the rolling component, therefore, a replacement of the crankshaft steel is required. Apart from this, the tribology of the rolling contacts has been shown to be detrimental when lubricated with current engine oils. Therefore, this paper investigates the tribological performance of potential crankshaft bearing steels, i.e. DIN C56E2 (G55); DIN 50CrMo4 (G50); and DIN 100Cr6 (G3), while utilizing a state-of-the-art low viscosity 0W20 engine oil and under conditions prevalent to ICE. For this, damage mode investigation was performed in a disc-on-disc setup. Based on the results, wear damage of DIN 100Cr6 discs was shown to be dependent on the steel grade of which the counterpart disc was made from and surface hardness difference between both discs. In addition, surface fatigue and wear damage can be completely eliminated by selecting a proper surface roughness and hardness combination. Also, while under an elevated roughness level, engine oil was shown to promote both surface fatigue and wear damage through the work of ZDDP additives, which under extreme conditions can act as an extreme pressure (EP) additive. The residual stress measurements using the XRD technique revealed relatively high compressive residual stresses for G55 and G50 in comparison to G3 steel after surface induction hardening. In addition, no significant changes in residual stress for G55 and G50 were observed after the test. In contrast, relatively high tensile stress was observed for G3 near the surface region. This suggests that the most commonly used 100Cr6 bearing steel, in this case, is the most susceptible to surface fatigue.

scholarly journals Running-in and micropitting behaviour of steel surfaces under mixed lubrication conditions

2016 ◽  
Vol 101 ◽  
pp. 59-68 ◽  
Author(s):  
A. Clarke ◽  
I.J.J. Weeks ◽  
R.W. Snidle ◽  
H.P. Evans
Keyword(s):  
Mixed Lubrication ◽  
Steel Surfaces ◽  
Lubrication Conditions

scholarly journals Influence of Steel Surface Composition on ZDDP Tribofilm Growth Using Ion Implantation

2021 ◽  
Vol 69 (2) ◽  
Author(s):  
Mao Ueda ◽  
Amir Kadiric ◽  
Hugh Spikes
Keyword(s):  
Steel Surface ◽  
Surface Composition ◽  
Formation Rate ◽  
Bearing Steel ◽  
Lubricant Formulation ◽  
Aisi 52100 ◽  
Steel Alloying ◽  
Steel Surfaces ◽  
Analytical Tools ◽  
Ball On Disc

AbstractThis paper examines the influence of steel surface composition on antiwear tribofilm formation by ion-implanting typical steel alloying elements, Ni, Mo, Cr, V and W, into AISI 52100 bearing steel surfaces. Such implantation changes the chemical composition of the steel surface but has relatively little effect on its mechanical properties or topography. The behaviour of zinc dialkyldithiophosphate (ZDDP) antiwear additive was studied. The study employs a ball on disc tribometer with ability to monitor tribofilm development and a range of analytical tools including STEM-EDX, XPS and FIB-TEM to analyse the formed tribofilms. It was found that Ni implantation promotes ZDDP tribofilm formation while Mo and Cr implantation deters tribofilm growth. V and W implantation do not significantly change tribofilm formation. Results on the influence of ZDDP concentration on tribofilm formation rate with different implanted metals suggest that one important mechanism by which steel composition influences tribofilm formation may be by controlling the extent of ZDDP adsorption. This study shows the importance of steel surface composition on ZDDP response and also demonstrates a powerful way to study and potentially improve the tribological performance of machine components via a combination of lubricant formulation and surface modification.

scholarly journals Contact stiffness and damping of spiral bevel gears under transient mixed lubrication conditions

Friction ◽  
2021 ◽  
Author(s):  
Zongzheng Wang ◽  
Wei Pu ◽  
Xin Pei ◽  
Wei Cao
Keyword(s):  
Contact Stiffness ◽  
Mixed Lubrication ◽  
Asperity Contact ◽  
Spiral Bevel Gears ◽  
Bevel Gears ◽  
Dry Contact ◽  
Spiral Bevel ◽  
Stiffness And Damping ◽  
Lubrication Conditions ◽  
Film Lubrication

AbstractExisting studies primarily focus on stiffness and damping under full-film lubrication or dry contact conditions. However, most lubricated transmission components operate in the mixed lubrication region, indicating that both the asperity contact and film lubrication exist on the rubbing surfaces. Herein, a novel method is proposed to evaluate the time-varying contact stiffness and damping of spiral bevel gears under transient mixed lubrication conditions. This method is sufficiently robust for addressing any mixed lubrication state regardless of the severity of the asperity contact. Based on this method, the transient mixed contact stiffness and damping of spiral bevel gears are investigated systematically. The results show a significant difference between the transient mixed contact stiffness and damping and the results from Hertz (dry) contact. In addition, the roughness significantly changes the contact stiffness and damping, indicating the importance of film lubrication and asperity contact. The transient mixed contact stiffness and damping change significantly along the meshing path from an engaging-in to an engaging-out point, and both of them are affected by the applied torque and rotational speed. In addition, the middle contact path is recommended because of its comprehensive high stiffness and damping, which maintained the stability of spiral bevel gear transmission.

Effectiveness of multi-shape laser surface texturing in the reduction of friction under lubrication regime

2016 ◽  
Vol 68 (1) ◽  
pp. 116-124 ◽  
Author(s):  
Dawit Zenebe Segu ◽  
Pyung Hwang
Keyword(s):  
Hydrodynamic Lubrication ◽  
Surface Texturing ◽  
Laser Surface ◽  
Laser Surface Texturing ◽  
Textured Surface ◽  
Content Type ◽  
Laser Ablation Process ◽  
Specific Formula ◽  
Steel Surfaces ◽  
Lubrication Conditions

Purpose – The purpose of this paper is to investigate and discuss the effect of multi-shape laser surface texturing (LST) steel surfaces on tribological performance. Design/methodology/approach – The textured surface with some specific formula arrays was fabricated by laser ablation process by combining patterns of circles and triangles, circles and squares and circles and ellipses. The tribological test was performed by a flat-on-flat tribometer under dry and lubrication conditions, and results were compared with that of untextured surface. Findings – The results showed that the textured surface had better friction coefficient performance than the untextured surface due to hydrodynamic lubrication effect. Through an increase in sliding speed, the beneficial effect of LST performance was achieved under dry and lubrication conditions. Originality/value – This paper develops multi-shape LST steel surfaces for improving the friction and wear performance under dry and lubrication conditions.

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