Automotive Bearings Research Articles

TRIBOLOGICAL PERFORMANCE OF PERFLUOROPOLYETHER (PFPE)-BASED GREASE FOR POTENTIAL APPLICATION IN AUTOMOTIVE BEARINGS

This study aims to evaluate the tribological performance of various commercially available perfluoropolyether (PFPE)-based greases in order to assess their potential application in automotive bearings. The composition and specification of the greases are taken into consideration for the analysis. The thermal oxidative stability of the selected grease is determined through oxidative thermo-gravimetric analysis test. Subsequently, the greases are evaluated for their frictional and wear behaviour using a ball-on-disk tribometer. To assess the wear condition of the ball and disk, a digital microscope with Amscope software is employed. The study reveals a scarcity of PFPE lubricant applications in the automotive sector. Among the greases tested, GPL 205 exhibits the highest thermal oxidative stability, characterized by the highest onset temperature of 321°C. Conversely, GPL 215 demonstrates superior friction reduction and anti-wear properties.

Comparison Study On Pinch-Hitting Vibration Signal Analysis for Automotive Bearing: I-KazTM and I-Kaz 3D

Rotating machines are now an essential part of the automotive industry. Meanwhile, a bearing is playing the most important component of rotating machinery. To sustain the system's smooth running, maintenance methods such as preventive maintenance, breakdown maintenance, and predictive maintenance are used. Under preventive maintenance, vibration analysis is used to diagnose machines bearing faults. The main objective is to recognize bearing defects in a mechanical device by acquiring signals from the bearing using data acquisition hardware. This analysis is conducted under various load torque conditions, speeds, and defect types. A modular hardware configuration consisting of an accelerometer acquires the vibration signal. The signals are analyzed by using I-kazTM and I-kaz 3D signal analysis and its main objective is to observe the degree of dispersion data from its mean point. This analysis resolves the issues associated with time domain analysis. This pinch-hitting analysis research was conducted in two stages. The first stage is an experimental process that uses 3 types of bearings, the healthy (BL), inner race fault (IRF), and defect at outer race (ORF) bearing on the Machine Fault Simulator and forces with a different type of speed (1000, 1500 and 2500 rpm) and load variation (0.0564, 0.564 and 1.1298 N-m). In the second stage, computing the coefficient value and plots of signal’s I-kazTM and I-kaz 3D based on the bearings type were done accordingly. As a result, the analysis for detecting inner race fault, the deviation percentage averages calculation obtained the I-kazTM coefficient shows a better result with 96.86% by comparing to the I-kaz 3D that achieves 94.20%. Similarly, for the outer race defect, I-kazTM lead with 65.40% compared to I-kaz 3D with only 54.82%.

Study of Tribological Properties of Bulk Nanostructured Aluminum and Copper Samples Applicable in Automotive Bearing Application

Using lightweight systems and friction reduction approaches are two main contributors towards modern and efficient powertrains in the automotive industry. New materials and processes are required to achieve the demanding and ever-increasing performance requirement of automotive systems. Nanostructure induced by severe plastic deformation methods involves bimodal microstructures and hence, shows exceptional mechanical characteristics which can be exploited for automotive application. Through this study, samples were prepared using pure copper, aluminum alloy (series 7000) and were processed to attain bulk nanostructured samples using a Single Step High Pressure Torsion technique with appropriate dimensions applicable as the rolling elements of automotive bearings. The induced nanostructures resulted micro hardness and frictional characteristics of the bulk samples were assessed using transmission electron (TEM) and atomic force (AFM) microscopies as well as microhardness evaluations. The results revealed that a fully refined nanostructured samples were achieved with 90% increase in the hardness at the outer diameter of the sample. The AFM measurements indicated that the friction coefficient of nanostructured copper and aluminum samples were ~ 25 and ~ 45% less than that of both the unprocessed samples, respectively. Characteristics of treated samples suggest that these processes can be potentially used in demanding conditions of rolling element bearings with reduced weight and frictional losses.

Modelling of Nanoindentation of TiAlN and TiN Thin Film Coatings for Automotive Bearing

Bearings are critical components for the transmission of motion in machines. Automotive components, especially bearings, will wear out over a certain period of time because they are constantly subjected to high levels of stress and friction. Studies have proven that coatings can extend the lifespan of bearings. Hence, it is necessary to conduct studies on coatings for bearings, particularly the mechanical and wear properties of the coating material. This detailed study focused on the mechanical properties of single-coatings of TiN and TiAIN using the finite element method (FEM). The mechanical properties that can be obtained from nano-indentation experiments are confined to just the Young’s modulus and hardness. Therefore, nanoindentation simulations were conducted together with the finite element method to obtain more comprehensive mechanical properties such as the yield strength and Poisson’s ratio. In addition, various coating materials could be examined by means of these nanoindentation simulations, as well the effects of those parameters that could not be controlled experimentally, such as the geometry of the indenter and the bonding between the coating and the substrate. The simulations were carried out using the ANSYS Mechanical APDL software. The mechanical properties such as the Young’s modulus, yield strength, Poisson’s ratio and tangent modulus were 370 GPa, 19 GPa, 0.21 and 10 GPa, respectively for the TiAlN coating and 460 GPa, 14 GPa, 0.25 and 8 GPa, respectively for the TiN coating. The difference between the mechanical properties obtained from the simulations and experiments was less than 5 %.

Corrosion and scratch resistance of DLC coatings applied on chromium molybdenum steel

Diamond-like carbon (DLC) coatings found many industrial applications in various fields, such as in aerospace, automotive bearing and electronic applications. DLC coatings performances are strictly correlated to their structure and composition which can be optimized controlling the substrate bias voltage (SBV). In this research, the corrosion and scratch resistance of DLC coatings applied on chromium molybdenum steel has been evaluated by electrochemical, microscopical and spectroscopical techniques. It has been observed that increasing the SBV leads to harder and more protective coatings, but decreases the resistance to delamination during scratch testing. Corrosion was always triggered at local defects of the Cr/C gradient interlayer, where the DLC layer was easily delaminated, exposing the chromium molybdenum steel substrate. The results of this study suggest that a better control of the Cr/C deposition parameters are necessary to further enhance corrosion resistance.

Enhancement of tribological properties of pure copper through cold sprayed MoS2 coating

Pure copper chosen as substrate was coated with Molybdenum Disulphide (MoS2) through cold spray coating method. A coating thickness of 123 ± 10 μm was obtained while a hardness improvement of 34.5% was obtained on comparing coated over uncoated substrate. Dry sliding wear analysis performed on coated pin specimens by varying process parameters such as applied load (10, 20, 30 N), sliding distance (750, 1250, 1750 m) and sliding velocity (0.75, 1.5 2.25 m s−1) revealed an increasing wear rate trend as applied load increases whereas an initial increase followed by a drastic decrease trend was observed for sliding velocity. Wear decreased initially followed by a slow rise, as sliding distance increases. ANOVA analysis confirmed highest influence for applied load, followed by sliding velocity and sliding distance. Confirmation experiments validated the regression model generated through RSM, which confirmed adequacy of model. For applied load, a wear mechanism transition from mild to severe wear was observed whereas, for sliding distance, the presence of an oxide layer was observed, which makes it suitable for automotive bearings and cylinder liners.

The effects of laser surface texture applied to internal combustion engine journal bearing shells – An experimental study

Abstract We present an experimental study into the impact of surface texturing on crank shaft bearing friction. This was achieved by applying a series of laser-etched patterns to the surface of shell components and comparing friction measurements - obtained using a journal bearing test rig - to those of a non-texture reference. Tests were performed under a range of applied loads, speeds and lubricant viscosities in order to simulate the operating conditions encountered in an engine. Three texture configurations were assessed with varying dimple density and area coverage. The lubricant film temperature was also measured in order to remove shear heating effects and deduce accurate friction values. The bearing shell with a texture pattern applied to the whole of its circumference showed substantial reduction in friction (approximately 18%) when compared with the non-textured reference. This reduction in friction increases as the film thickness increases (i.e.: moving right on the Stribeck curve) and is most pronounced under full film hydrodynamic conditions. Friction reductions of up to 13% were observed using bearing shells that were only textured outside the loaded region. This is attributed to a reduction in shear rate due to an increased gap without alteration of the pressure generation and is important since this texture configuration maintains its effectiveness, even after the heavily loaded region becomes worn. These reported hydrodynamic friction reductions have practical implications for automotive bearings.

Bearing Tough Conditions: Plastics Carry the Load in Automotive Bearing Systems

Bearing Tough Conditions: Plastics Carry the Load in Automotive Bearing Systems

Hierarchical k-nearest neighbours classification and binary differential evolution for fault diagnostics of automotive bearings operating under variable conditions

Electric traction motors in automotive applications work in operational conditions characterized by variable load, rotational speed and other external conditions: this complicates the task of diagnosing bearing defects. The objective of the present work is the development of a diagnostic system for detecting the onset of degradation, isolating the degrading bearing, classifying the type of defect. The developed diagnostic system is based on an hierarchical structure of K-Nearest Neighbours classifiers. The selection of the features from the measured vibrational signals to be used in input by the bearing diagnostic system is done by a wrapper approach based on a Multi-Objective (MO) optimization that integrates a Binary Differential Evolution (BDE) algorithm with the K-Nearest Neighbor (KNN) classifiers. The developed approach is applied to an experimental dataset. The satisfactory diagnostic performances obtain show the capability of the method, independently from the bearings operational conditions.

Scanning thermal microscopy techniques for polymeric thin films using temperature contrast mode to measure thermal diffusivity and a novel approach in conductivity contrast mode to the mapping of thermally conductive particles

Advances in production are leading to increasing use of polymeric thin films in applications such as automotive bearings. Two approaches have been developed to study the thermophysical properties of these thin films: The first technique based on Flash theory uses a scanning thermal microscopy (SThM) tip in temperature contrast mode to measure thermal diffusivity over a nano-scale area. The SThM tip is in contact with the upper surface of the film to detect a heat pulse delivered by a microelectromechanical heater platform from the lower surface. The second technique is a conductivity contrast mode SThM based approach for measuring the size and distribution of thermally conducting particles in thin film polymeric coatings. Topographical and thermal conductivity data are combined to produce a “correlation analysis value” 3D particle map of the coating. Good practice and a case study are highlighted.

A Fuzzy Logic based Model to Predict MRR in Flashing Operation of Precision Steel Ball Manufacturing Process

Bearing balls are special highly spherical and smooth balls, most commonly used in ball bearings. Applications of Steel balls are widely in critical aeronautical bearings, guidance system balls for space and military applications, precision valves, automotive bearings and other applications where higher precision & smoothness is required. To investigate the effect of various input parameters during flashing operation experiments are performed. Here input variables are Pressure between two plates, No. of Grooves in plates & RPM of Ring Plate. Each factor varies at two levels; the design is 23 factorial design which requires 8 runs to complete all the possible combinations. Here MRR is consider as response. A fuzzy model is developed to predict the MRR in context of these input parameters. Fuzzy model uses fuzzy expert rules, triangular membership function and centroid area method for defuzzyfication process using MATLAB fuzzy logic tool box. The result shows minimum error is 1.2% and maximum error is 9.2% of the fuzzy model, it shows that the fuzzy model can effectively predict the MRR for decided range of input parameters.

Effect of Various Parameters on Spread in Flashing Operation of Precision Steel Ball Manufacturing Process

Precision balls are the key elements for critical aeronautical bearings, guidance system balls for space and military applications, precision valves, automotive bearings and other applications. In all these applications higher precision is required. Hence, the development of a more economical finishing method becomes a critical problem in the application of advanced Steel ball manufacturing. Spread is the variation in the Diameter of Balls of same batch or lot. Spread is a very critical quality parameter which must be controlled while operation. The experiment for Flashing was designed using a full factorial design with two levels for each input variable (2k factorial design). Since there are three factors, each at two levels, the design is 23 factorial designs. Factors taken for the experiments are Pressure between two plates, No. of Grooves in plates & RPM of Ring Plate. From the main effect plot pressure should be at lower level. Same way from RPM should be at lower level & No. of grooves should also be at lower level to achieve minimum spread. Also at these level of the parameters the residual (error) found from the regression model is -0.625 which is very less so the value of these parameters satisfying the required function. Also from the experiments Percentage contribution are pressure having 43.55%, No. of Grooves having 23.31% & RPM having 23.31% effect on spread.

Fatigue behaviour FEM modeling of deep groove ball bearing mounted in automotive alternator submitted to variable loading

Ball bearings subsurface materials are subjected to rolling contact fatigue with multiaxial stress state during loading cycle. The complex operating conditions of automotive bearings are different from classic operating conditions their fatigue crack initiation predicted by standards can be seen underestimated. This work presents a numerical approach of ball bearings to evaluate its fatigue behaviour in order to predict the life. A preliminary study has been done to evaluate the load distribution in the bearings. The results are integrated in a numerical dynamic model to study the bearing material rolling fatigue behaviour in constant and variable loading cases. By using fatigue criteria and damage laws, the analysis of stress state in bearing material leads to life prediction or the number of cycles before crack initiations. These results are compared to current standard methods used for ball bearing life prediction.

04/02166 Thermal modelling and experimental validation of ground temperature distribution in greenhouse: Ghosal, O. et al. International Journal of Energy Research, 2004, 28, (1), 45–63

We present an experimental study into the impact of surface texturing on crank shaft bearing friction. This was achieved by applying a series of laser-etched patterns to the surface of shell components and comparing friction measurements - obtained using a journal bearing test rig - to those of a non-texture reference. Tests were performed under a range of applied loads, speeds and lubricant viscosities in order to simulate the operating conditions encountered in an engine. Three texture configurations were assessed with varying dimple density and area coverage. The lubricant film temperature was also measured in order to remove shear heating effects and deduce accurate friction values.The bearing shell with a texture pattern applied to the whole of its circumference showed substantial reduction in friction (approximately 18%) when compared with the non-textured reference. This reduction in friction increases as the film thickness increases (i.e.: moving right on the Stribeck curve) and is most pronounced under full film hydrodynamic conditions. Friction reductions of up to 13% were observed using bearing shells that were only textured outside the loaded region. This is attributed to a reduction in shear rate due to an increased gap without alteration of the pressure generation and is important since this texture configuration maintains its effectiveness, even after the heavily loaded region becomes worn. These reported hydrodynamic friction reductions have practical implications for automotive bearings.

Longer life for automotive bearings

Longer life for automotive bearings

Microstructural Influences on Fatigue Crack Initation and Early Growth Behaviour in Plain Bearing Al-based Linings

Fatigue initiation and subsequent short and long crack growth has been investigated in an typical automotive bearing system, focussing on the behaviour of the aluminium-tin-silicon lining material. Crack initiation appears to be associated with decohesion of the interface between the primary, globular silicon and the aluminium matrix. Short crack growth, and crack growth at low Delta K levels in the long crack case, appears to be tortuous and highly microstructurally dependent, deviating towards secondary phase/matrix interfaces. At higher Delta K levels crack growth occurs principally through the aluminium matrix, and classical striations are seen. Multiple crack initiation is seen in the multiphase bearing lining material and crack coalescence gives rise to the dominant crack. Uncoalesced cracks appear to arrest at a critical surface crack length, whose dimension has been linked to sub-surface crack deflection within the lining material once the crack reaches the steel backing.

A Study of the Thermohydrodynamic Performance of Steadily Loaded Journal Bearings

A comprehensive thermohydrodynamic (THD) analysis of steadily loaded journal bearings has been developed that includes mass conserving cavitation, full solution of the 3-D energy equation in the oil film, heat conduction in the bushing and journal, mixing of hot circulating oil with fresh supply oil and solution of the inverse problem (given the load, find the film thickness). The temperature distribution in the oil film and bushing is found using a coupled approach where the same 3-D energy equation is solved in both the oil film and bushing. With this approach the steady-state problem can be solved without iterations between the thermal solutions in the oil film and the bushing, thereby allowing ready analysis of multilayer bushings. Predictions of the analysis compared very well with measurements reported by Dowson et al. (1). A thermohydro-dynamic study of bearing performance as a function of clearance for a typical automotive bearing revealed that there is an optimum clearance that gives the largest minimum-film thickness. In contrast, isothermal analyses did not show any optimum.

A Finite Volume Analysis of the Thermohydrodynamic Performance of Finite Journal Bearings

A rigorous thermohydrodynamic (THD) analysis of finite journal bearings has been developed. THD analysis not only allows a more accurate prediction of the bearing performance characteristics, but it also provides the temperature distribution in the bearing. It involves the simultaneous solution of the Reynolds and energy equations and can handle a wide variety of flow situations, including reverse flow, recirculating flow, and cavitation. The overall numerical scheme is based on a fully conservative finite-volume formulation. The calculated results are compared with the published literature. The qualitative agreement is good. Sample calculations for a typical automotive bearing show that the oil supply pressure and supply configuration significantly affect the bearing performance.