bluuebunny/crossref_metadata_2025_split huggingface dataset:
A method of measuring ‘zero‐wear’ of the cylinder liner
Authors: Pawlus Pawel 
Published: July 2006

AbstractIn this paper, new methods of linear wear estimation of the cylinder liner are proposed. They can be used if the deepest honed valleys remain unaltered during the wear process. In the first part of the paper, the possibility of using various amplitude parameters as measures of wear is studied. The second part presents a new procedure for cylinder liner wear analysis based on the ‘fax‐film’ method that allows us to estimate the wear of the cylinder liner without disassembly of the cylinder‐piston‐piston ring group.
Open‐gear lubrication: Meeting industrial requirements using laboratory techniques
Authors: de Vaal Philip L. 
Published: July 2006

AbstractThis paper gives a general overview of open‐gear lubricants. In order to evaluate contending lubricants, laboratory tests are often used as a preliminary screening. When care is taken to perform laboratory tests under conditions which represent the actual operating conditions, simple laboratory tests can be conducted to evaluate products before a product is selected for use in trial runs on actual equipment. In planning laboratory tests, the industrial requirements need to be clearly defined, from the perspective of the supplier, as well as that of the user. Factors such as environmental acceptance, toxicity, and ease of disposal of spent lubricant play as important a role in the formulation of new products as do requirements related to performance, like pumpability, sprayability, adhesiveness, load‐carrying ability, and wear protection capability.
Wear simulation of spur gears
Authors: Flodin Anders , Andersson Sören 
Published: July 2006

AbstractThis paper deals with prediction of wear in spur gears, which has been calculated using an approach in which the wear depth on a tooth surface is integrated over time using the Euler integration method. Variations in pressure distribution over the surface have been considered, as well as changes in curvature and surface profile of the teeth as they wear. The paper focuses on the use of an appropriate wear model for simulating wear using calculated conditions between high‐performance slow‐running lubricated spur gears. A numerical model for prediction of surface interaction of spur gears developed earlier by the authors has been applied as the basis for the simulation of wear using different wear models. Owing to the nature of the wear models, methods of calculating the contact temperature have been investigated for the specific case of interacting gear teeth. It was found that a linear wear model, when compared with a more complex oxidation model and with a model based on adsorption of lubricant molecules, satisfactorily predicts wear. It was also found that it is the geometry of the gears that causes sliding velocity to be the dominant wear‐inducing factor, and so determines the general nature of the wear behaviour.
An improved crater grinding micro‐abrasion test
Authors: Engqvist H. , Axén N. , Hogmark S. 
Published: July 2006

AbstractThe crater grinding test was originally developed for micro‐abrasion evaluation of thin hard coatings. It is capable of determining the wear constants of the coating and substrate individually, even for very thin coatings. Crater grinding micro‐abrasion tests also make very small wear scars and are thus virtually non‐destructive.This paper evaluates modifications of the crater grinding test configuration in order to increase its accuracy and repeatability. In particular, new geometries of the wearing wheel have been tested on bulk samples of cemented carbides and alumina, and the effects of misalignments in the test equipment are also investigated. The proposed improvements to the test are shown to generate results with better accuracy and repeatability.
Oxidation stability of gasoline engine lubricants: Effect of base‐oil chemistry in laboratory and engine tests
Authors: Faure D. , Hipeaux J. C. , Guevellou Y. , Legros A. 
Published: July 2006

AbstractThis paper presents a laboratory test called the Iron Catalysed Oxidation Test (ICOT), where air is bubbled through an oil sample at 165 °C. This test, shorter than the CEC L‐48 test, provides an easy method of gasoline engine lubricant screening. A basic study has shown that this kind of test is suitable for the discrimination of base‐oil properties and that the oil viscosity increase at the end of the test is highly indicative of the oxidation processes at work. In this study, the base‐oil assessment is carried out with an API SG SAE 15W‐40 oil, and the results depend directly on the aromaticity of the base oil. Several engine test sequences, including CEC L‐55‐T‐95: TU3M HT, were also applied to these formulations, which differ only in their base oils. The results of those sequences where oil consumption was low roughly correlated with the laboratory test results. However, when there was a high loss of volatile matter in the engine tests, the oil viscosity increase was greatly modified, and this parameter can override the effect of oxidation.
Pitting load capacity test on the FZG gear test rig with load‐spectra and one‐stage investigations
Authors: Höhn B.‐R. , Oster P. , Schedl U. 
Published: July 2006

AbstractLubricants in their combination of base oil and additive influence the pitting and micropitting load‐carrying capacity of cylindrical gears. The aim of the FVA ‘Pitting test’ research project was to develop and establish a test method on the standard FZG gear test rig with a centre distance a = 91.5 mm. Two different test procedures were proposed, one using a load spectrum and the other a constant load. These tests can be used to determine the relative pitting load capacities of reference and candidate oils. From these results the pitting load‐carrying capacity can be calculated.
On the influence of some test parameters on the results of oscillating sliding tests
Authors: Klaffke D. 
Published: July 2006

AbstractThe friction and wear behaviour of materials is often characterised in laboratory tests using a simple ball‐on‐flat configuration. From this type of test can be derived information useful in guiding the development of tribomaterials and in helping select candidate materials for specific applications. A large variety of tribotesting methods exists, and indeed several are not yet standardised. One of these methods is the oscillating sliding test, where a ball moves in relation to a disc, usually with small strokes. This method is almost non‐destructive and can be applied to very small specimens. One of the most important parameters in laboratory tests is the humidity of the surrounding air. Experimental results on the friction and wear characteristics of different ceramics tested against different ball materials at room temperature in oscillating sliding contact are presented here and discussed, taking into account the effects of the test duration, relative humidity, and counterbody material.
Mechanical testing of hydraulic fluids
Authors: Reichel Jürgen 
Published: July 2006

AbstractThe antiwear properties of hydraulic fluids are important because hydraulic pump and motor wear is costly. While international hydraulic fluid performance standards continue to be developed, e. g., the ISO/TC28/SC4 committee's draft ISO DIS 11158 ‘Specifications for mineral oil hydraulic fluids’, the normal hydraulic fluid performance specifications represent minimum requirements. Performance specifications for nonmineral oil hydraulic fluids are also being developed.Typically, both the user and the fluid manufacturer possess insufficient objective information about the antiwear properties of special fluids, e. g., environmentally acceptable hydraulic fluids (EAHF) or fire‐resistant hydraulic fluids (FRHF) for use in hydraulic equipment such as axial‐piston pumps, vane pumps or radial‐piston motors. Manufacturer's specifications must therefore be determined. The required lubrication properties can be determined by either laboratory pump tests or a field trial, often at the customer's expense. The lubrication properties of a hydraulic fluid should ideally be determined under conditions that are equivalent to field practice.This paper will discuss the use of the vane pump test and the FZG gear test to gauge ‘recommended’ hydraulic fluid performance; many non‐mineral hydraulic fluids, such as environmentally acceptable hydraulic fluids, fire‐resistant fluids or synthetic hydraulic fluids, cannot be used in axial‐piston systems based only on results obtained with these tests, and additional testing is always required. Proposals are made for testing of such fluids on a variable‐load test rig. These tests are done with axial‐piston pumps, or other similar displacement systems, and are intended to determine the industrial suitability of non‐mineral hydraulic fluids.
Tribological properties of plasma nitrided AISI 4140 steel under dry and lubricated sliding conditions
Authors: Podgornik B. , Vižintin J. 
Published: July 2006

AbstractIn this investigation, the microstructural, mechanical and tribological properties of plasma and pulse plasma nitrided AISI 4140 steel have been investigated in comparison to hardened steel. The influence of nitriding case depth, as well as the presence of a compound layer, have been tribologically examined for both dry and lubricated sliding. Testing was carried out on a pin‐on‐disc machine in which surface‐treated pins were mated to hardened ball bearing steel discs. The surface treated samples were characterised using metallographic, SEM, microhardness and profilometric techniques, before and after wear testing. The resulting wear loss and coefficient of friction were monitored as a function of load and of test time. The results showed improved tribological properties of the AISI 4140 steel after plasma and pulse plasma nitriding as compared to the hardened steel, in both dry and lubricated sliding. However, the compound layer should be removed from the surface, either by mechanical means or by decreasing the amount of nitrogen in the nitriding atmosphere, in order to avoid impairment of the tribological properties by fracture of the hard and brittle compound layer, followed by formation of hard abrasive particles.
Fundamentals of tribotesting
Authors: Klaffke Dieter 
Published: July 2006

AbstractTribology is an experiment‐oriented branch of a complex, interdisciplinary science, in which testing plays a major role in the solution of technical problems, in the field as well as in the development of tribomaterials. Various test methods are used for this purpose, and the results are sensitive to the choice of test method and test conditions.In this paper, the effects of test parameters on friction and wear results are considered, some selected results of model tests with different types of materials are presented, and guidelines are derived, that help improve the reliability and level of confidence of tribological tests performed in laboratories.
The use of topography‐based parameters for the assessment and prediction of surface wear
Authors: Sherrington I. , Mercer S. 
Published: July 2006

AbstractThis paper examines the use of surface parameters as ‘tools’ for assessing and predicting surface wear. It begins by briefly reviewing other work published on wear assessment based on entirely topography‐based parameters, and concludes that other elements of surface condition are needed, in addition to topography, to assess and characterise the contact if topography‐based parameters are to be employed to predict wear. This paper discusses why areal measurements of bearing area and plasticity index are suitable candidates as a basis for assessing and predicting surface wear, and outlines the potential value of using these parameters in conjunction with a wear equation. The validity of this suggestion is illustrated by some preliminary data from a series of pin‐on‐disc wear experiments involving areal assessments of the bearing area and plasticity index of the rough tip of a brass pin. Predictions of the first stage of a wear simulation are compared to experimental data, and the paper concludes by presenting some general conclusions and suggestions about how the work could be developed.
Modifications to improve the accuracy of a four‐ball test apparatus
Authors: Lacey P. I. , Davenport D. W. , D'spain F. M. , Reed D. J. 
Published: July 2006

AbstractThe four‐ball wear test machine is one of the most widely used tribological tools in both research and industry. In general, the test geometry is self‐aligning and minimises the opportunity for random variation. Nonetheless, accurate control of the test parameters remains vital to repeatability and reproducibility. The present paper details a number of modifications to a commercially available test apparatus that have been found to improve accuracy. The applied load on some apparatus was found to vary from the correct value, probably due to frictional drag in the loading system. A feedback control loop was designed and fitted to the applied load mechanism, which resulted in significantly improved accuracy. Finally, the apparatus was fully automated, with complete computer control of all test parameters. Under this, following cleaning and assembly of the test specimens, the required test procedure could be selected from a menu of standard methods, and the computer program then adjusted the test parameters according to the method selected, greatly reducing the possibility of operator error.
Stick‐slip with the slip phase as the starting point
Authors: van de Velde Frederik , de Baets Patrick , Degrieck Joris 
Published: July 2006

AbstractIn the literature, the stick‐slip phenomenon is always explained and modelled as starting from an initial stick phase. However, stick‐slip can also occur after a decrease in the imposed velocity, commencing above the critical (stick‐slip‐free) velocity. In this paper, it will be shown how stick‐slip can originate from a situation of pure sliding (without stick phases), if the slope of the friction force‐relative sliding velocity relation (F‐vrel gradient) is negative. The F‐vrel gradient used to study stick‐slip must, because of the interaction between the friction force and the dynamic behaviour of the mechanical system, be derived from velocity changes with the same time‐constant as the mechanical system of which the friction interface is part. It will also be shown that steady‐state friction data, and dynamic (non‐stationary) friction results obtained for relatively large (but fast) velocity variations, can lead to completely false conclusions related to stick‐slip.
Wear investigation of spur gear teeth
Authors: Flodin Anders 
Published: July 2006

AbstractAn FZG back‐to‐back gear test machine has been used to investigate the initial wear of spur gears. By making plastic replicas of the tooth surfaces, and measurements of the same using a 3D stylus instrument, the wear pattern has been analysed. The wear tests were run on the machine according to a predefined schedule. During planned stops, negative surface replicas were made. The replicas were measured, and the amount and distribution of wear analysed. SEM pictures were also taken of the tooth surfaces, and several different types of damage were identified. The results were compared with simulated results using identical loading and geometry. It was found that the wear was quite severe at the root of the wheels and also significant at the tip. The wear was also found to form an overloaded wave pattern on the original involute form of the tooth.
A study of electrical pitting of journal bearings with water‐contaminated lubricant
Authors: Prashad Har 
Published: July 2006

AbstractThe investigations reported in this paper concern the effect of the use of a degraded lubricant on bearing life. A diagnosis of the premature failure of the hydrodynamic journal bearings of a synchronous condenser has been carried out. The surface of the failed bearings has been examined and the cause of the failure investigated. A theoretical analysis has also been undertaken to calculate the number of cycles that take place before failure occurs. The number of cycles thus established matched that of the cycles/duration of operation before the premature failure of the bearings. The process leading to the premature failure and the role of the degraded lubricant have been identified. Remedial measures have been successfully implemented to reuse the existing bearings. Measures have been suggested to avoid repeated failures.The theoretical analysis has the potential to ascertain the shaft voltage once the severity of the physical damage on the liner surface of the bearing and the duration of its operation have been established.
A study of the measurement of surface temperature at a cam/tappet contact
Authors: Ito Akemi , Yang Lisheng , Negishi Hideo 
Published: July 2006

AbstractCam/tappet wear is one of the most difficult reliability and durability problems to predict during the development of a prototype engine valve‐train system. In the present study, the cam/tappet surface temperature was measured and calculated to determine the effect of surface temperature on the lubricating conditions at a cam/tappet contact. The measurement method, sometimes called the dynamic thermocouple technique, was based on the Seebeck effect: by using different materials for the cam and tappet, the cam/tappet contact point becomes the hot junction of a ‘thermocouple’. The cam/tappet contact surface temperature can therefore be measured continuously. The measured temperature results show good agreement with predictions. Temperature spikes, however, were not found in the test using new oil, but were shown by the theoretical model. Such results indicate that the cam/tappet interface operates in effective lubricating conditions, even when the oil temperature is relatively high. Further research with degraded oil supplied at high temperature is needed for a thorough understanding of abnormal cam wear.
Tribological and mechanical investigation of SiO2 and Si3N4 coatings on fused silica and borosilicate glass
Authors: Klaffke D. , Beck U. 
Published: July 2006

AbstractAmorphous SiO2 and Si3N4 plasma‐enhanced chemical vapour deposited (PECVD) coatings were deposited on two different substrate materials (fused silica and borosilicate glass), with three coating thicknesses (0.1, 0.5, and 1.0 μm). The mechanical properties (hardness and elastic modulus) were determined by depth‐sensing indentation, with loads from 700 mN down to 0.1 mN. Tribological behaviour was studied in instrumented oscillating sliding tests at room temperature with a ball‐on‐flat arrangement, in which the coated disc was tested against an alumina ball, at a load of 1 N. Interpretation of the measurement of hardness and modulus of the coatings has to take into consideration the influence of layer thickness and the effect of the substrate. Tensile film stress and crack generation were only observed for Si3N4 on fused silica above a threshold thickness. Friction and wear measurements show that the coating has an effect on friction, while wear is affected by the thin coatings only for a short running‐in phase. The morphology of the wear scars indicates that the coatings have good adhesion. Despite crack generation, delamination effects were not observed. Indentation patterns similarly showed excellent lateral homogeneity of the mechanical properties over the entire film surface, and indicated that load‐displacement curves may be used to characterise the system.
Recent trends in the total characterization of new‐generation base fluids
Authors: Singh I. D. , Sahoo S. K. , Adhvaryu A. 
Published: July 2006

AbstractThe quality of lubricating base oils used worldwide is changing rapidly as a result of stringent environmental regulation and the pressing need for oils to perform well under severe operating conditions. For example, although the base oil market in India now depends entirely on conventional group I base oils, group II and III base oils will soon be mandatory in lubrication formulation. These oils are generally more stable towards oxidation due to the virtual absence of heteroatom‐containing compounds and to their low aromatic content. The analytical procedures developed over the years for the characterization of new and used group I mineral base oils will not be successful for all the requirements of these new oils. Thus, a systematic study is required to test the universal validity of characterisation methodology for these new‐generation base fluids. This paper focuses on the use of various analytical techniques for base oil characterization and the methodology required for the total characterization of new‐generation base oils.
Inertia and couple‐stress effects on squeeze‐film characteristics with reference to biological bearings
Authors: Walicki Edward , Walicka Anna 
Published: July 2006

AbstractCouple stresses affect lubrication when additives are used or the lubricant contains long‐chain molecules. Such couple stresses may have a considerable effect on the behaviour of bearings in practice. The influence of couple stresses and lubricant inertia on the mechanical parameters of a curvilinear thrust bearing with a squeeze film is considered in this paper. Simulation of the squeeze‐film behaviour of a human joint modelled as a spherical bearing is discussed as an example.
Friction property study of the surface of ZDDP and MoDTC antiwear additive films using AFM/LFM and force curve methods
Authors: Ye Jiping , Kano Makoto , Yasuda Yoshiteru 
Published: July 2006

AbstractThe friction properties and material differences of the surface of ZDDP and MoDTC antiwear additive films, which give clear evidence of different friction coefficients in a pin‐on‐disc test, have been studied using atomic force microscopy (AFM)/lateral force microscopy (LFM) and force curve methods. The AFM/LFM observations show that the friction force on the surface of MoDTC additive films over the sliding area of a steel disc is lower and the friction force of ZDDP additive films is higher than that of afilmless area. Lateral force scope‐trace evaluations reveal that the ratio of the friction forces on the surface of the ZDDP film, the filmless area, and the MoDTC film under the same normal force is approximately 1.5:1.0:0.7. Force curve measurements indicate that the surface materials of the ZDDP film, thefilmless area, and the MoDTC film differ according to their attractive forces, that is 29 nN for the ZDDP film, 22 nN for the filmless area, and 12 nN for the MoDTC film. These results correspond to the friction behaviour in the pin‐on‐disc test and also agree with the idea of the formation of solid MoS2 lubricant from MoDTC additives on the surface of the antiwear film.