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Aiming at the problems of premature bearing failure caused by multi-point contacts between the steel ball and the raceway of four-point contact ball bearings, taking QJ214 four-point contact ball bearings as the research object, the ball and the raceway contact models were established, and the causes of multi-point contacts between the ball and the raceway were analyzed when the structural parameters and working condition parameters were changed. The results show that with the increase of the coefficient of inner and outer raceway groove curvature radius or the thickness of inner and outer gasket, the contact state between the ball and the raceway may be changed from three-point contact to two-point contact, and then to three-point contact. At constant speed condition, with the reduction of axial load, the contact state between the ball and the raceway may be changed from two-point contact to three-point contact. When the rotational speed and the axial load are constant, the increase of radial loads may make the contact state of some steel balls and the raceway change from two-point contact to three-point contact, and then to four-point contact. The research findings may provide reference for avoiding the cat's eye ring wear failure caused by multi-point contact during the running of four-point contact ball bearings. [ABSTRACT FROM AUTHOR]

Ball bearings fault detection with the aid of ultrasound technique is of great importance. Hence, this paper evaluates signal processing of ultrasounds sent by faults and addresses relevant challenges. In this regard, the waveforms of ultrasound signals were analyzed for different types of faults and considering specification of ultrasound channels to enhance the perception of ultrasound signal processing. For this purpose, different conditions have been considered such as waveform fading and the likelihood of frequency fading at lower signal-to-noise ratios. Furthermore, the sensitivity of ultrasonic sensors to fault detection at higher frequencies and the probability of the modulation have been assessed, and modeling results have been presented. In addition to modeling, fault detection in a ball bearing of an electromotor has been studied through an industrial-empirical case study. Therefore, the bearing signals have been processed for fault-free, initial fault, and advanced fault conditions. The studied fault emerged in several months (without hand intervention) and was then intensified over time. According to results, the envelope technique is capable of extracting fault frequencies of ball bearings. Also, high-pass filters have been employed to demonstrate signal shape mode and impulse generation in detail. Moreover, it has been shown that the growth of initial faults can generate new frequencies and fault frequency harmonics other than the fault frequencies of ball bearings. Also, important tips on the ultrasound fault detection of electromotor were provided with a potential effect on the entire fault detection process. These tips came from the author's experiences obtained by monitoring rotary machines. In which, they can serve as a beneficial tool for monitoring of such machines in industrial sites. [ABSTRACT FROM AUTHOR]

In this study, based on the experimental analysis of heat generation in deep groove ball bearings, the thermal nodes about the deep groove ball bearings is established by using heat network method. The temperature field of the bearing is simulated with finite element software, and the result obtained from the simulation is in good agreement with the comparison of the theoretical calculation results. The bearing test bench was used to analyze the bearing, and the experimental results again proved the effectiveness of the thermal network method. It was found that the bearing speed played a significant role in the working temperature of a bearing, which was consistent to the analysis of the thermal network method, verifying the feasibility of the thermal network method to solve bearing temperature, laying the foundation for the subsequent research on the heat transfer law of motor and rolling bearing. [ABSTRACT FROM AUTHOR]

Purpose: For a lightweight and accurate description of bearing temperature, this paper aims to present an efficient semi-empirical model with oil–air two-phase flow and gray-box model. Design/methodology/approach: First, the role of lubricant/coolant in bearing temperature was discussed separately, and the gray-box models on the heat convection inside a bearing cavity were also created. Next, the bearing node setting scheme was optimized. Consequently, a novel semi-empirical two-phase flow thermal grid for high-speed angular contact ball bearings was planned. With this model, the thermal network for the selected motored spindle was built, and the numerical solutions for bearing temperature rise were obtained and contrasted with the experimental values for validation. The polynomial interpolation on test data, meanwhile, was also performed to help us observe the temperature change trend. Finally, the simulations based on the current models of bearings were implemented, whose corresponding results were also compared with our research work. Findings: The validation result indicates that the thermal prediction is more accurate and efficient when the developed semi-empirical oil–air two-phase flow model is employed to assess the thermal change of bearings. Clearly, we provide a more proper model for the thermal assessment of bearing and even spindle heating. Originality/value: To the best of the authors' knowledge, this paper introduced the oil–air separation and gray-box model for the first time to describe the heat exchange inside bearing cavities and accordingly presents an efficient semi-empirical oil–air two-phase flow model to evaluate the bearing temperature variation by using thermal network method. Peer review: The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-06-2023-0180/ [ABSTRACT FROM AUTHOR]

This article presents a study on condition monitoring and predictive maintenance, highlighting the importance of tracking ball bearing condition to estimate their Remaining Useful Life (RUL). The study proposes a methodology that combines three algorithms, namely Variational Mode Decomposition (VMD), Decision Tree (DT), and Extreme Learning Machine (ELM), to extract pertinent features and estimate RUL using vibration signals. To improve the accuracy of the method, the VMD algorithm is used to reduce noise from the original vibration signals. The DT algorithm is then employed to extract relevant features, which are fed into the ELM algorithm to estimate the RUL of the ball bearings. The effectiveness of the proposed approach is evaluated using ball bearing data sets from the PRONOSTIA platform. Overall, the results demonstrate that the suggested methodology successfully tracks the ball bearing condition and estimates RUL using vibration signals. This study provides valuable insights into the development of predictive maintenance systems that can assist decision-makers in planning maintenance activities. Further research could explore the potential of this methodology in other industrial applications and under different operating conditions.

In this study, finite element method (FEM) is applied to investigate the effect of material defect orientation on subsurface crack initiation in rolling bearings. First, the history of stress intensity factors (SIFs) of a subsurface cubic material defect is calculated. SIFs calculation is conducted when it is parallel to the rolling surface of a bearing ring ( φ = 0 ∘ ) under a ball rolling on the ring. Then, the effect of defect orientation, varying from φ = 0 ∘ to φ = 30 , 45 and 60 ∘ , on the history of SIFs is investigated. It is deduced that changing the defect orientation results in a threefold increase in the equivalent SIF range compared to parallel orientation. [ABSTRACT FROM AUTHOR]

In order to investigate the thermal variations of axial static stiffness of motorized spindle unit, a thermal modeling method of spindle axial static stiffness is established by combining the numerical simulation technology with analytical method. Firstly, based on a thermoelastic ring cylinder model and the Hertz contact theory, the analytical model of temperature rise–axial static stiffness thermal variation effect of spindle-angular contact ball bearing system is constructed; then, the spindle structural thermal model considering its coolant heat transfer is obtained by using the finite element heat–fluid–solid coupling simulation technology, to solve temperature rises of spindle bearings. Based on them, the Bushing element is used to analyze the stiffness of the bearing assembly in the thermal–structural coupling simulation modeling of motorized spindle unit and thus to simulate the thermal variation effects of spindle axial static stiffness. Ultimately, the variation tendencies of the spindle axial static stiffness under various thermal conditions are analyzed by using this model, and the obtained results are compared with their corresponding test data. The comparisons show that this modeling method can accurately predict the thermal variation tendencies of axial static stiffness during spindle operations. Then the temperature rises of spindle structure can cause its axial static stiffness to harden, which is associated with the thermal increase of bearing preload. The conclusions have the guiding significance for thermal balance design and optimization of spindle structure. [ABSTRACT FROM AUTHOR]

The study of the bearing fatigue life in high-speed gearboxes is an integral part of high-speed gear transmission research. There is still a lack of research on the analysis and calculating the bearing internal dynamic load and fatigue life considering gear engagement and centrifugal force simultaneously. Therefore, the paper proposes a new approach to acquire the internal load and fatigue life of the deep groove ball bearing in a high-speed gearbox system. Firstly, the modeling method of the gear mesh, flexible shaft, high-speed deep groove ball bearing, and housing is established, constructing the gearbox system dynamic model, which has the ability to calculate the bearing internal load. Then, the calculation method for analyzing the fatigue life of bearings is given based on the linear damage theory. The results show that the gear engagement and centrifugal force have meaningful effects on bearing internal loads and fatigue life, especially at high speeds. Both of them should be considered when evaluating the bearing life. The calculation method and model proposed in this paper provide a new technical approach for service performance evaluation and reliability design of high-speed deep groove ball bearing. [ABSTRACT FROM AUTHOR]

Bearings play a crucial role in vehicle structures and systems, enabling relative motion between essential components such as shafts and housings. However, during service, many bearings are prone to failure due to factors like excessive loading, improper lubrication and ineffective sealing. To optimize production and minimize maintenance costs, accurately forecasting a bearing's Remaining Usable Life (RUL) becomes essential. This study focuses on three different deep groove ball bearings used in diverse vehicle applications, including washing machines, electric motors, gear drives and pumps. Utilizing Python programming language and input parameters such as radial and axial loads, speed and shift hours, RUL of the bearings was calculated. The results demonstrated a strong correlation between RUL and shift hours as well as the load acting on the bearings. Notably, a 25% increase in bearing RUL was observed with a decrease in shift hours, facilitating informed decisions on optimal machine operating hours and cost-effective maintenance strategies for vehicle systems. [ABSTRACT FROM AUTHOR]

The occurrence and aggravation of local defects in ball bearings are closely linked to the skidding behavior of the ball. Previous studies have given less attention to investigating the impact of localized defects on the problem of bearing skidding. To investigate the dynamic response of defective bearings due to skidding, a dynamic model of the ball bearing is developed that considers various factors, including self-rotation, revolution, and radial motion of the ball, as well as the contact forces and friction forces of ball/cage and ball/race, time-varying displacement excitation, and elastohydrodynamic lubrication (EHL). Experimental signals collected from a machinery fault simulator test rig are used to validate the accuracy of the proposed model. The impact of race defects on the vibration characteristics of the bearing is analyzed, and the patterns of variation in contact and friction forces within one cycle of inner race rotation are described. The results indicate that the presence of defects intensifies the force fluctuation of the ball and causes it to deviate from its normal rolling condition. By comparing the skidding characteristics of a healthy bearing with a defective one under slippage, local defects will increase the skidding ratio of bearings. The proposed model can investigate the impact of race defects on the vibration response of ball bearings under the skidding condition. [ABSTRACT FROM AUTHOR]

Purpose: Due to high speeds, heavy loads, large slide-to-roll ratios (SRR) and other variable operating conditions, some rolling bearings that have been working in harsh conditions may experience flash temperatures in the contact area, which may result in early damage like smearing and then affect service life. This study aims to investigate the flash temperature phenomenon of rolling bearings through theoretical and experimental analysis. Design/methodology/approach: A technology for measuring temperature distribution in rolling ball on disk contact under lubrication was developed. The test-rig can simulate the ball bearing contact. The effects of working conditions such as entrainment speed, load, SRR and lubricating oil viscosity on the flash temperature were investigated. Findings: The results of the theoretical calculation and experiments indicate that the parameters promoting the reduction of film thickness in elastohydrodynamic lubrication are always related with the number of flash points, even film thickness reduced to mixed lubrication. The flash temperature is easier to happen in conditions of high SRR, heavy load, slow entrainment speed and low viscosity oil. Originality/value: This work conducts an experimental study on the flash temperature phenomenon, providing a test technology for bearing lubrication and failure investigation. Peer review: This author has opted into Transparent Peer Review available at: https://publons.com/publon/10.1108/ILT-04-2023-0104 [ABSTRACT FROM AUTHOR]

A general methodology for dynamic modeling and analysis of deep groove ball bearing used in the crank-slider mechanism of punching machine is presented in this paper. The time-varying loads applied at the inner ring of this bearing can be obtained by analyzing the planar multibody systems. The bearing joint has been modeled by introducing a nonlinear constraint force system, which takes into account the contact stiffness interaction between the rolling elements and the raceways. The four-degree-of-freedom dynamic equations for the inner and outer rings of the bearings is established by Newton's second law. By numerical calculation, the variations of the load, trajectory, FFT frequency domain response, and x direction phase trajectory and Poincare of the inner ring, and the contact force on each ball element are discussed. The results indicate that the present methodology can not only be used to analyze the overall dynamic behavior of crank-slider mechanism and the deep groove ball bearing used in punching machine, but also to obtain the dynamic loads of the inner ring and ball in bearing. Therefore, the dynamic loads on ball elements can provide a basis for the strength checking, fatigue life calculation and wear analysis of the deep groove ball bearing. [ABSTRACT FROM AUTHOR]

In order to analyze the bearing wear in the spindle system considering different speed and load conditions, a four-bearing spindle system was investigated. Two different working conditions, Case I and Case II, are considered. Case I condition has lower spindle speed and higher external loads and preload than Case II condition. Based on Archard model, a new wear depth model of angular contact ball bearing is presented which takes into account the influence of lubrication on bearing wear. The wear depths of inner and outer raceways for angular contact ball bearings are calculated based on the motion parameters and contact parameters of ball elements which are obtained by spindle system model. The effects of spindle speed, angular misalignment, external load and surface roughness on the wear depths of bearings are comparatively studied. Increasing spindle speed at Case I condition can significantly increase bearing wear. Angular misalignment may be beneficial to individual bearing, but overall, no angular misalignment is the most beneficial to spindle system. The change rate of wear depth of bearing raceway with external loads at Case I condition is much greater than that at Case II condition. The surface roughness can significantly affect the bearing wear in the spindle system, especially at Case I condition. [ABSTRACT FROM AUTHOR]

Impact features caused by the bearing defects can be used to detect the defect sizes. The current defective vibration models for ball bearings only considered the effect of defect length. The effects of the defect width, defect depth, and ball-raceway contact deformations are ignored to simplify the vibration models. Meanwhile, the impact forces and processing when the balls pass through the defect are not accurately calculated. However, those above factors have a great effect on the impact features. To overcome those issues, a new impact model of a deep groove ball (DGB) bearing with a defect based on the previous model is established by using the exponential and trigonometric functions. Based on the collision and geometry models in the previous works, the effects of the defect width, defect depth and ball-raceway contact deformation are considered. The proposed impact model can accurately simulate the actual vibration signal of defective ball bearings. It can be used to detect the defect sizes. The impact positions when the balls entering the defect of outer ring are calculated. The abnormal changes in the bearing vibrations are analyzed. The results can provide useful references for understanding the impact features excited by the bearing defects. • A comprehensive impact model of a defective ball bearing is presented. • Effects of the defect sizes and contact deformation on vibrations are studied. • The presented impact model has a better accuracy than the traditional models. [ABSTRACT FROM AUTHOR]

This paper proposes a feature-based methodology for early bearing fault detection and classification in induction motors through current signals using the digital Taylor–Fourier transform (DTFT) and statistical methods. The DTFT allows the application of narrow bandwidth digital filters located in the spurious current signal components, wherewith it is possible to gain information to detect bearing issues and classify them using statistical methods. The methodology was implemented in MATLAB using the digital Taylor–Fourier transform for three fault types (bearing ball damage, outer-race damage, and corrosion damage) at different powering conditions: power grid source at 60 Hz and adjustable speed drive applied (60 Hz, 50 Hz, 40 Hz, 30 Hz, 20 Hz, and 10 Hz) in loading and unloading conditions. Results demonstrate a classification accuracy between 93–99% for bearing ball damage, 91–99% for outer-race damage, and 94–99% for corrosion damage. [ABSTRACT FROM AUTHOR]

One of the most important indices of bearing raceway, roundness, has an important influence on the life and performance of the bearing. Currently, shoe-type centerless grinding (STCG) is a core process for the fabrication of the raceway surface. Some researchers have carried out studies in this field; however, the reason and extent of the influence of process parameters on the workpiece roundness in the STCG operation for the internal raceway of the 6208 ball bearings are not clear up to now. In this paper, new research on the effects of process parameters on workpiece roundness in the STCG operation for the internal raceway of the 6208 ball bearings is presented. The influence of the angular placement of the two shoes, as well as the technology parameters including the offset between the rotational centers of the workpiece and the magnetic drivehead (e), the normal feed rate (Snf), the speed of the workpiece (nw), and the grinding depth (af), on the roundness of the raceway surface were investigated both theoretically and experimentally to solve the difficulties in the STCG operation to ensure the roundness of the raceway surface. Based on the research results, a guideline for selecting initial process parameters is introduced to ensure the roundness of the bearing raceway in the STCG operation for the internal raceway of 6208_ball bearings on the 3MK136B grinder. [ABSTRACT FROM AUTHOR]

In this work, we proposed a method for coating the whole surfaces of bearing balls uniformly by carbon film with a rotatable ball clamp. We studied the carbon/carbon friction with a self-designed current-carrying ball bearing friction test system. A notable and instant friction force drop of 28% and significant carbon film wear alleviation were found when currents were applied. By using TEM-, SEM-, and EDS-analysis, special carbon stacks with a mixture of large wear particles and oxide were found in the wear areas under current applied condition. We elucidated the current-carrying friction mechanisms as follows: (1) wear particles formation; (2) wear particles charged by tribomicroplasma; (3) formation of surface passivated carbon stacks under electric force; (4) sliding between passivated carbon surfaces. This work may facilitate the development of novel solid-lubricated ball bearings and lay some foundations for current-carrying rolling friction. [ABSTRACT FROM AUTHOR]

Sliding and spinning behaviors significantly affect the performance of rolling bearings, especially for dry-lubricated bearings, micro and macro sliding may lead to increased wear of the solid lubricating film. A unified rolling contact tribology analytical model is proposed for dry-lubricated angular contact ball bearings (ACBBs) considering the extreme conditions including high combined loads and rolling contact effects. A comprehensive solution framework is proposed to ensure the robustness of the model under different loading conditions. Equilibrium equations are solved to study the effects of friction coefficients, rotating speeds, and combined loads on the skidding and spinning characteristics of the ACBB. The results show that the rolling contact effects and combined loads significantly affect the skidding and spinning performance of the ACBB. Further analysis reveals that the skidding mechanism is related to the interaction between ball kinematical motion and traction forces. The developed analytical model is proved to more accurately predict the bearing kinematical and tribological behavior as it discards the raceway control hypothesis and considers the macro/micro-slipping, creepage, and self-spinning motions of the ball, which is validated using both the existing pure axial loading dry-lubricated ACBB model and the classical Jones—Harris model. The study would provide some guidance for the structure and lubrication design of dry-lubricated ACBBs. [ABSTRACT FROM AUTHOR]

Performance of ball bearings in the motion converter subassembly of an internally driven, single-speed, torque-split, twin configuration pericyclic transmission prototype is evaluated to extend the analytical knowledge base on this innovative transmission concept. A dynamic model of the transmission is developed with high-fidelity models of the installed rolling element bearings to determine their reactions. Attention is focused on the pair of ball bearings supporting the motion converter subassembly which are subjected to a complex combination of loads, including radial and axial forces, moments, carrier motion, and possibly internal preload. Then the influence of internal axial clearance and preload on the behavior of the rolling elements is analyzed with a fully dynamic ball bearing model. Provisions to consider the carrier motion and a robust integration algorithm for component orientations are presented. Finally, a microstructure-based fatigue life simulation of the critical bearing component is performed to demonstrate the effect of clearance/preload on bearing reliability. [ABSTRACT FROM AUTHOR]

This research paper introduces a novel approach using dominant frequency analysis to diagnose inner race faults in rolling ball bearings of three-phase induction motor. The main objective of the proposed scheme is to identify damaged bearings by analyzing their characteristic frequency components within a specific time interval in segmented signal. This work has been carried out on vibration signal data provided by Bearing Center Case Reserve Western University (CWRU), USA. In this study, IR007, IR014 and IR021 bearing defects are analyzed by Frequency Statistical Analysis in MATLAB. Mean and standard deviation of dominant frequencies are computed from the recorded vibration signals after dividing the signal into multiple segments of equal length. It is observed that both frequency mean, and standard deviation have been found to be highly sensitive with variations of motor speed and connected load. Therefore, motor speed is also studied to calculate the statistical parameters. The test results suggest that the proposed scheme provides comprehensive information about fault analysis through vibration data and could potentially aid researchers in fault analysis using the CRWU datasets. Overall, this paper presents a promising approach to diagnose the faults in the inner race of rolling ball bearings using frequency domain analysis and statistical parameters. [ABSTRACT FROM AUTHOR]

The results of petro- and paleomagnetic studies of phase-I gabbrodiorites from the Lower Amur Complex of the Zhuravlevka-Amur terrane (Poni massif, Poni-Mulinsky ore cluster) are presented. They were used to determine that during the formation of the Lower Amur intrusive complex (Cenomanian-Turonian) the Amur River zone was located approximately 10° north of its current position between the Central Sikhote-Alin fault in the east and the Priamursky fault in the west. It is shown that starting from the middle of the Cenomanian there were no latitudinal movements of the Amur River zone of the Zhuravlevka-Amur terrane relative to the Eurasian continent. However, a more than 20°-counterclockwise rotation of the zone relative to the continent was recorded, which is easily explained within the ball-bearing tectonic model under the impact of the Amur and Central Sikhote-Alin en echelon left-lateral strike-slip faults. The left-lateral strike-slip fault systems were likely to be the channels for mantle material supply during the formation of the largest Malmyzh porphyry copper deposit, which, along with the Poni-Mulinsky ore cluster, is part of the Lower Amur mineragenic zone. [ABSTRACT FROM AUTHOR]

Base isolation applications are becoming popular in the seismic design of resilient structures and infrastructures. Even though the response of the bearings is widely studied under cyclic displacements, limited information is available for bearing response under sustained lateral loads. These types of loads can develop sustained lateral displacement in the bearing. During the holding time under sustained lateral displacement, the creep or stress relaxation may significantly change the properties of the bearings and may affect the response in the reloading stage. This research paper aims at assessing the influence of short-term lateral creep on the hysteretic response of rubber bearings, and ball rubber bearings. To this end, experimental testing on different elastomeric bearings under imposed lateral displacement is performed. For each device, the lateral response is measured, and the advantages and disadvantages are discussed in terms of strength, stiffness, energy dissipation and equivalent damping. The loss of load under sustained lateral displacement is experimentally assessed and the effects of creep in the design procedure of a base isolated system are discussed. [ABSTRACT FROM AUTHOR]

The effect of variable DC bearing current amplitude, bearing current polarity, mechanical force, rotation speed, bearing temperature, and number of the balls on the fluting in an axial ball bearing type 51208 is investigated under DC currents. The results are obtained from two different test setups with two different lubricants (mineral-oil-based grease and polyglycol oil). The speed varies between 100 rpm and 2000 rpm, the axial bearing force between 200 N and 2400 N, the DC current amplitude between 0.5 A and 20 A, the bearing temperature between 29 °C and 80 °C, the number of steel balls per bearing between 3 and 15, and the test duration between 6 h and 168 h. The results show that with a higher bearing current density and/or a higher bearing speed, a lower bearing force and/or a lower bearing temperature, a bigger number of roller elements, but also at a negative polarity of a DC electric bearing current, the occurring of fluting is more probable and occurs at an earlier stage of operation. [ABSTRACT FROM AUTHOR]

Copyright of Bearing is the property of Bearing Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Bearing is the property of Bearing Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Lubrication Engineering (0254-0150) is the property of Editorial Office of LUBRICATION ENGINEERING and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In order to achieve dynamic adjustment of the bearing preload, a new structure of self-adjusting preload device for spindle bearings was designed. The symmetrical structure was adopted in construction of the device that can meet the preload adjustment requirements of both coaxial and back-to-back mounted bearings by adjusting the output direction of the centrifugal force; according to changes in spindle speed, automatic adjustment of the bearing preload by using the centrifugal force generated by the mass element. The operating mechanism of the device was analyzed by designing a bearing variable preload system. The dynamic preload performance of the device at different speeds was investigated using ANSYS finite element simulation analysis software for contact non-linearity analysis. The research results show that the device can provide a large preload at low speeds and automatically reduce the preload of the bearing at high speeds in the form of a quadratic relationship with good preload performance. The study provides a new idea for the design of bearing preload structures. [ABSTRACT FROM AUTHOR]

This study has focused on analyzing the impact of material characteristics and grinding conditions on the surface roughness in ELID grinding of ceramic materials intended for bearing balls. The main research objective was to examine the feasibility of achieving the required surface roughness for G5 class bearing balls through a high-efficiency and high-precision ELID grinding process. Three types of silicon nitride specimens and two types of grinding wheels with cBN and diamond abrasives were prepared for the experiments. An HP (high-pressure) specimen was fabricated through high-temperature and high-pressure sintering at 1700 °C for 2 h, containing a composition of Y2O3 and MgO in Si3N4, while GPS 1hr and GPS 6hr specimens were prepared using gas-pressure sintering for 1 h and 6 h, respectively. From the experimental results, it has been confirmed through surface morphology and surface roughness analysis that material characteristics and grinding parameters affect the surface roughness of silicon nitride ceramics during the grinding process. The surface ground with a #2000 diamond wheel is at a level that can satisfy the required surface roughness, 0.014 um or less in G5 class bearing balls. Based on the analysis of surface morphology and roughness in grinding processes, the #325 cBN wheel exhibited excellent performance in rough grinding, while the #2000 diamond wheel demonstrated highly effective surface finishing performance, indicating that the combination of these two abrasives can be effectively utilized for high-efficiency and high-precision nanosurface machining of silicon nitride ceramics. [ABSTRACT FROM AUTHOR]

The thermophysical, rheological, and tribological properties in lubricant are essential for preserving the engines, power steering systems, and engine components from damage caused by friction and wear. The incorporation of nano-sized particles into lubricating oils has been reported to enhance these properties. Therefore, this study explores the impacts resulting from the incorporation of graphene, multiwalled carbon nanotubes (MWCNT), doublewalled carbon nanotubes (DWCNT), and single-walled carbon nanotubes (SWCNT) at a quantity of 0.04 grams into the SAE 5W-30 base oil. These nanoparticles were synthesized using a two-step method, resulting in nanolubricants. The addition of carbon-based nanomaterials increases the density and decreases the viscosity of the base lubricant. The flow of nanolubricants exhibits non-Newtonian shear thinning behavior during the test at elevated temperatures. The results of the four-ball tribo-tester test reveal the increase of Coefficient of Friction (CoF) values and the extent of wear scar area. Further, the Scanning Electron Microscopy (SEM) analysis was employed to observe the wear morphology of the nanolubricants on the SKF RB-12.7/G20W ball bearing. Its results indicate a prevalence of groovetype wear as compared to conventional lubricants. [ABSTRACT FROM AUTHOR]

Environmental concerns and depleting mineral oil resources have forced us to develop environmentally acceptable lubricants. In this study, tribological properties of rice bran oil containing imidazolium-based ionic liquid 1- ethyl 3methylimidazolium dicyanamide ([EMIM][DCN]) (ILa), phosphonium based ionic liquid Trihexyltetradecylphosphonium bis(2,4,4-trimethylpentyl) phosphinate ([P66614][BTMPP]) (ILb) and titanium oxide (TiO2) nanoparticles (NPs) as hybrid additives have been investigated using four ball tester. Rice bran oil based ionanolubricants (INLs) were formulated with different concentrations of ILa, ILb and TiO2 NPs. Among all investigated ionanolubricant samples, rice bran oil containing 0.03 ∅ of TiO2 NPs and 0.5 vol.% of ILa showed the lowest AWSD. The improved characteristics of rice bran oil based INLs can be attributed to the ball bearing effect and tribofilm formation. [ABSTRACT FROM AUTHOR]

Position and velocity vectors between ball-rings, ball-cage, and cage-ring in space were considered to refine the friction heat generation rate model of ball bearings. The relationship between the position vectors of each part of a bearing in space was analyzed to determine the bearing's status of contact bearing. Hertz contact theory and Coulomb friction law were employed to calculate the normal and friction forces at the contact points, respectively. The relationship between the velocity vectors of each part in space was analyzed, and the relative sliding velocity between two parts in contact was obtained. Friction heat generation rate of bearings was calculated as the product of friction force and relative velocity. Parameters such as bearing speed, axial load, radial load, and the groove curvature radius coefficient of bearing inner and outer rings were all investigated in the case of ball bearing heat generation. Theoretical calculation and experimental results indicate that the bearing friction heat generation rate is associated with the bearing rotation speed and bearing thrust load at ultra-high rotation speed, whereas the radial load has insignificant effect. Meanwhile, a suitable inner-outer groove curvature radius coefficient can significantly reduce the bearing friction heat generation rate. [ABSTRACT FROM AUTHOR]

Purpose: The study aims to the distribution rule of lubricating oil film of full ceramic ball bearing and improve its performance and life. Design/methodology/approach: The paper established an analysis model based on the fluid–solid conjugate heat transfer theory for full ceramic ball bearings. The distribution of flow, temperature and pressure field of bearings under variable working conditions is analyzed. Meanwhile, the mathematical model of elastohydrodynamic lubrication (EHL) of full ceramic ball bearings is established. The numerical analysis is used to study the influence of variable working conditions on the lubricant film thickness and pressure distribution of bearings. The temperature rise test of full ceramic ball bearing under oil lubrication was carried out to verify the correctness of simulation results. Findings: As the speed increased, the oil volume fraction in full ceramic ball bearing decreased and the surface pressure of rolling element increased. The temperature rise of full ceramic ball bearings increases with increasing speed and load. The lubricant film thickness of full ceramic ball bearing is positively correlated with speed and negatively correlated with load. The pressure of lubricating film is positively correlated with speed and load. The test shows that the higher inner ring speed and radial load, the higher the steady-state temperature rise of full ceramic ball bearing. The test results are in high agreement with simulation results. Originality/value: Based on the fluid–solid conjugate heat transfer theory and combined with Reynolds equation, lubricating oil film thickness formula, viscosity temperature and viscosity pressure formula. The thermal analysis model and EHL mathematical model of ceramic ball bearings are established. The flow field, temperature field and pressure field distribution of the full ceramic ball bearing are determined. And the thickness and pressure distribution of lubricating oil film in the contact area of full ceramic ball bearing were determined. Peer review: The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-05-2023-0126/ [ABSTRACT FROM AUTHOR]

Copyright of Bearing is the property of Bearing Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Bearing is the property of Bearing Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Lubrication Engineering (0254-0150) is the property of Editorial Office of LUBRICATION ENGINEERING and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The tribological characteristics of a below 1 mm micro ball bearing comprising steel disc and cages coated with thin copper and silver films were investigated. Electroplating and laser cutting were used to manufacture used elements. Friction was measured using a linear stage and an adapted version of a friction-loop method. The obtained results show an interesting relationship between the geometric properties of the micro scale thrust bearing and their performance and operational stability, which can be correlated to similar relationships observed in the macro scale. The most optimal design of the bearing showed stable operation, with the simplified rolling resistance coefficient in the range 0.002 to 0.003, independently of applied load, which was in range 150 mN to 1500 mN. The possibility of creating easily manufacturable micro ball bearings with a low rolling resistance coefficient comprised solely of cheap and sturdy elements was shown. [ABSTRACT FROM AUTHOR]

Purpose: This work investigates the nonlinear vibration and dynamical behavior of a twin-spool rotor assembly supported by ball-bearings and squeezed film dampers (SFDs) using an order-reduced system model. Methods: The nonlinear vibration and dynamical behavior is investigated for a twin-spool rotor assembly supported by ball-bearings and SFDs. The rotor is spatially discretized with the finite-element method, and the nonlinear governing equation of motion of the system is derived considering the loading characteristics of SFD and ball bearing. To reduce the dimension of the original model, the post-processed nonlinear Galerkin method (NGM) is employed to project the original system onto a low-dimensional approximate inertial manifold (AIM) with a relatively smaller number of degrees of freedom. The convergence of the NGM with AIM is verified through comparisons of displacement and energy between the original and the reduced systems. The optimal choice of the number of master modes (NMM) is determined to form the reduced model for nonlinear vibration analyses. Results: The model reduction through the NGM with AIM is effective and efficient. The amplitude–frequency response, bifurcation and the Poincaré map are obtained to demonstrate the complexity in the rotor dynamics due to the nonlinearity in SFDs and ball bearings. [ABSTRACT FROM AUTHOR]

The distribution of lubricating oil in the bearing cavity is of great significance to bearing lubrication and cooling. A new idea is provided to further study the ball bearings lubrication, to achieve effective lubrication of bearings. The flow field of oil injection lubrication ball bearings is studied by the moving particle semi-implicit (MPS) method. The accuracy of the numerical calculation method is verified by experiments. The oil distribution of the bearing lubrication flow field and churning torque of the ball and cage at different speeds are analyzed. The research results show the maximum oil content in the bearing cavity is distributed in the range of about 90° to 120°. As the increase of rotating speed, the number of particles in the bearing cavity decreases. The churning torque decreases with the increase of rotating speed and increases with the increase of the oil viscosity. This study provides a new numerical calculation method for the lubrication flow field of ball bearings.

Full-ceramic ball bearings are widely used in aerospace, gas engines, and extreme working conditions. The research on vibration characteristics of full-ceramic ball bearings under different pre-tightening forces and oil supply rates is relatively rare. In this paper, silicon nitride 6206 full-ceramic deep groove ball bearing is taken as the research object, the experiment of lubrication vibration characteristics of full-ceramic bearings is carried out on a bearing vibrometer by changing different pre-tightening forces and lubricating oil supply rates with the control variable method, the dynamic model of full-ceramic deep groove ball bearing under lubrication condition is established, and the influence of factors such as lubricating oil drag force, lubricating oil film thickness, rolling friction force, and pre-tightening force on bearing vibration are analyzed in essence. The experimental results show that the large vibration ratio of the bearing in the state of lack of oil is caused by insufficient oil supply, and when the oil supply rate is too high, the rolling body is dragged by too much drag force, which leads to an obvious increase in bearing vibration. The similarity between the solution signal and the measured signal of the dynamic model of full-ceramic bearing considering the drag force of the rolling body under different lubrication conditions is over 95%, which proves the reliability and accuracy of the dynamic model. [ABSTRACT FROM AUTHOR]

Ball bearings are the most critical components of rotating machinery in oil and gas companies. Typical research has focused on bearing failure detection based on bearing failure frequencies derived from the velocity spectrum. However, most bearing failures are caused by improper or insufficient lubrication. The current research utilizes a case study demonstrating when ball bearings must be replaced or relubricated due to poor lubrication conditions. Poor lubrication is the cause of natural frequency excitation in bearings, where rapid bearing damage is typically induced by poor lubrication film. According to experimental data in this study, the bearing failed due to natural frequency excitation. In addition, when analyzing a signal with the velocity spectrum, high frequencies are displayed. Bearing failure is detected without bearing failure frequencies using the natural frequencies of the bearing in the velocity spectrum signal. Moreover, an experimental investigation of the bearing failure of a liquid ring compressor was conducted utilizing a VIBXPERT II vibration analyzer and the Omni trend software. The velocity spectrum is derived based on a fast Fourier transform from a time signal. After lubricating natural frequencies must be disappeared from the velocity spectrum otherwise, the bearing is failed and must be changed. [ABSTRACT FROM AUTHOR]

This study addressed the issues related to the difficulty of determining the operating status of machine tool spindle bearings due to the high rotational speeds and rapid temperature fluctuations. This paper presents an optimized model that combines Convolutional Neural Networks (CNNs) and Informer to dynamically predict the temperature rise process of bearings. Taking the H7006C angular contact ball bearing as the research object, a combination of experimental data and simulations was used to obtain the training dataset. Next, a model for predicting the temperature rise of the bearing was constructed using CNN + Informer and the structural parameters were optimized. Finally, the model's generalization ability was then verified by predicting the bearing temperature rise process under various working conditions. The results show that the error of the simulation data source model was less than 1 °C at steady state; the temperature error of the bearing temperature rise prediction model was less than 0.5 °C at both the temperature rise and steady-state stages under variable rotational speeds and variable load conditions compared to Informer and Long Short Term Memory (LSTM) models; the maximum prediction error of the operating conditions outside the dataset was less than 0.5 °C, and the temperature rise prediction model has a high accuracy, robustness, and generalization capability. [ABSTRACT FROM AUTHOR]

Copyright of Bearing is the property of Bearing Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Bearing is the property of Bearing Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Bearing is the property of Bearing Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Bearing is the property of Bearing Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)