Performance studies of textured race ball bearing

2019 ◽  
Vol 71 (9) ◽  
pp. 1116-1123 ◽  
Author(s):  
Vivek Bhardwaj ◽  
R.K. Pandey ◽  
V.K. Agarwal
Keyword(s):  
Ball Bearing ◽  
Dynamic Performance ◽  
Critical Role ◽  
Operating Conditions ◽  
Frictional Torque ◽  
Bulk Temperature ◽  
Back Side ◽  
Ball Bearings ◽  
Content Type ◽  
Long Duration

Purpose The purpose of this paper is to develop an energy-efficient and dynamically improved thrust ball bearing using textured race. A texture has been used on the stationary race of the test bearing to conduct the long-duration experiment for exploring its tribological and vibrational behaviours under starved lubricating condition using micro size MoS2 blended grease. The performance behaviours of the textured race bearing have been compared with conventional bearing (i.e. having both races without textures) under the identical operating conditions for demonstrating the advantages of textured race. Design/methodology/approach Texture was created on stationary race of the test ball bearing (51308) using nano-second pulsed Nd: YAG laser. Performance parameters (frictional torque, temperature rise and vibrations) of textured ball bearings were measured under severe starved lubricating conditions for understanding the critical role of texture in the long duration of the test. S-type load cell and miniature accelerometer were used for measuring the frictional torque and vibration, respectively. Bulk temperature at stationary races (at the back side) of test bearings was measured in operating conditions using a non-contact infrared thermometer. Findings Significant reduction in frictional torque and decrease in amplitude of vibration with textured ball bearing were found even under the severe starved lubricating condition in comparison to conventional bearing. Originality/value There is dearth of research pertaining to the performance behaviours of ball bearings using textures on the races. Therefore, an attempt has been made in this study to explore the tribo-dynamic performance behaviours of a thrust ball bearing using a texture on its stationary race under severe starved lubricating condition for the longer duration of the test.

Kinematic investigation and fatigue life analysis of angular contact ball bearing in wide speed range based on raceway friction

2020 ◽  
Vol 72 (7) ◽  
pp. 845-850
Author(s):  
Yue Liu
Keyword(s):  
Fatigue Life ◽  
Peer Review ◽  
High Speed ◽  
Ball Bearing ◽  
Operating Conditions ◽  
Angular Contact Ball Bearing ◽  
Content Type ◽  
Speed Range ◽  
Uniform Model ◽  
Wide Speed Range

Purpose The purpose of this paper is to clarify the relationship between fatigue life and kinematics of angular contact ball bearing. It proposes a new modeling method of spin to roll ratio based on raceway friction, which is more accurate than the traditional raceway control theory. Design/methodology/approach The uniform model of spin to roll ratio based on raceway friction in a wide speed range is proposed using quasi-statics method, which considers centrifugal force, gyroscopic moment, friction force of raceway and other influencing factors. The accuracy is considerably improved compared with the static model without increasing too much computation. Findings A uniform model for spin to roll ratio of angular contact ball bearing based on raceway friction is established, and quite different relationships between fatigue life and speed under two operating conditions are found. Research limitations/implications The conclusion of this paper is based on the bearing basic fatigue life calculation theory provided by ISO/TS 16281; however, the accuracy of theory needs to be further verified. Practical implications This paper provides guidance for applying angular contact ball bearing, especially at a high speed. Originality/value This paper reveals the changing trend of fatigue life of angular contact ball bearing with the speed under different loads. Peer review The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-01-2020-0030

M-Pesa: an evolution in organisational strategy

2015 ◽  
Vol 5 (8) ◽  
pp. 1-11
Author(s):  
Mariam Cassim ◽  
Linda Ronnie
Keyword(s):  
Change Management ◽  
Business Model ◽  
Financial Services ◽  
Critical Role ◽  
Business Environment ◽  
Subject Area ◽  
Operating Conditions ◽  
Content Type ◽  
Successful Business

Subject area Change Management. Study level/applicability Postgraduate business courses, including MBA courses in change management and human resource management. Case overview This case study emphasises how important it is for organisations operating in today's turbulent and rapidly changing business environment to have an emergent approach to change. It focuses on the dilemmas faced by Hemmanth Singh, the newly appointed Managing Executive responsible for Mobile Commerce at Vodacom South Africa. Singh is responsible for the execution of the new strategy into financial services, the relaunch of M-Pesa into the South African market being the immediate task. The case sets the context for the relaunch of M-Pesa, and the reader is introduced to some of the limitations and challenges experienced by the company when trying to replicate a successful business model from one market to another, especially after an unsuccessful initial launch. Expected learning outcomes After reading and analysing the information contained in the case study and appendices, students should be able to evaluate the critical role that leadership needs to play when introducing and implementing a change initiative at an organisation that is stimulated by evolving external market conditions; understand the importance of adopting an emergent approach to change in current operating conditions; identify the factors that contribute to or hinder the creation and sustainability of an adaptive culture within an organisation; and appreciate the challenges of attempting to replicate a successful business model from one market into another. Supplementary materials Teaching Notes are available for educators only. Please contact your library to gain login details or email [email protected] to request teaching notes.

scholarly journals Experimental investigation of ball bearing lubrication conditions by shock pulse method

2019 ◽  
Vol 36 (1−2) ◽  
Author(s):  
Ratnesh Kumar Gupta ◽  
Vikas Rastogi ◽  
R C Singh ◽  
N Tandon
Keyword(s):  
Ball Bearing ◽  
Pulse Method ◽  
Operating Conditions ◽  
Condition Based Maintenance ◽  
Ball Bearings ◽  
Shock Pulse ◽  
Optimum Conditions ◽  
Wear And Tear ◽  
Lubrication Conditions ◽  
Bearing System

Lubricant (grease) is a vital requirement of ball bearing system. Grease not only protects ball bearing from wear and tear but performs various other functions that are essential for proper functioning of ball bearings. The lubricant (grease) under different conditions attains different properties which in turn affect the performance of the ball bearings. The effect of the condition of the lubricants on the performance of the ball bearings is well documented. the work reports about the investigation of ball bearing using shock pulse method by using two different instruments (Tester T2000 Model and Shock Pulse Meter 43A) of different operating conditions of ball bearing the condition such as used the quantity of grease as different percentage (0%, 25%, 50%, 75%, 100%) and bad quality grease (burn grease) at different rpm at a fixed load (10kg) and compare the normalized shock pulse value (dB) at different operating conditions. This method uses a piezo-electric accelerometer superimposed electrically as well as mechanically to about 32 kHz of resonant frequency. The result will help in bearing related to quantity as well as quality condition based maintenance choosing the optimum conditions for detecting the lubricant problem in ball bearing.

On the characteristics of gas foil conical bearings considering misalignment

2020 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Hongyang Hu ◽  
Ming Feng ◽  
Tianming Ren
Keyword(s):  
Film Thickness ◽  
Peer Review ◽  
Load Capacity ◽  
Dynamic Performance ◽  
Critical Role ◽  
Friction Torque ◽  
Misalignment Angle ◽  
Content Type ◽  
Stiffness Model ◽  
Dynamic Performances

Purpose The purpose of this paper is to study the characteristics of gas foil conical bearings (GFCBs) considering the misalignment, the static and dynamic performances with different misalignment cases were studied. Design/methodology/approach A test rig on the air compressor supported by GFCBs has been developed to measure the practicability. A nonlinear bump stiffness model and one-dimensional beam top foil stiffness model were used as a basis for the calculation of static and dynamic performance. The finite element method and finite difference method are adopted to solve the Reynolds equation and the film thickness equation coupled, in which different misalignment cases were considered by changing the film thickness. Findings The supporting performance of GFCB is excellent, and the film clearance plays a critical role. The misalignment effects depend on the assembled angle and the misalignment angle. The load capacity, friction torque, temperature of GFCB decrease when the misalignment assembled angle is between 120° and 240°, while the dynamic bearing stability is improved. The static and dynamic performances show the opposite law for the other assembled angles, and the misalignment effect is more dramatic when there is a larger misalignment angle. Moreover, the bearing and running parameters largely affect the bearing performance. Originality/value The present study focuses on the static and dynamic characteristics of GFCB and investigates the effects of misalignment on the bearing performance. Peer review The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-04-2020-0117

Dynamics of Rolling-Element Bearings—Part III: Ball Bearing Analysis

1979 ◽  
Vol 101 (3) ◽  
pp. 312-318 ◽  
Author(s):  
P. K. Gupta
Keyword(s):  
Ball Bearing ◽  
Dynamic Performance ◽  
Equations Of Motion ◽  
Ball Bearings ◽  
Rolling Element Bearings ◽  
Time Simulation ◽  
Rolling Element ◽  
Analytical Development ◽  
Critical Film Thickness ◽  
Bearing Analysis

An analytical formulation for the generalized ball, cage, and race motion in a ball bearing is presented in terms of the classical differential equations of motion. Ball-race interaction is analyzed in detail and the resulting force and moment vectors are determined. The ball-cage and race-cage interactions are considered to be either hydrodynamic or metallic and a critical film thickness defines the transition between the two regimes. Simplified treatments for the drag and churning losses are also included to complete a rigorous analytical development for the real-time simulation of the dynamic performance of ball bearings.

DLC-coated spur gears – part I: friction reduction

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Andreas Schwarz ◽  
Martin Ebner ◽  
Thomas Lohner ◽  
Karsten Stahl ◽  
Kirsten Bobzin ◽  
...  
Keyword(s):  
Thermal Insulation ◽  
Operating Conditions ◽  
Friction Reduction ◽  
Experimental Investigations ◽  
Bulk Temperature ◽  
Test Rig ◽  
Dlc Coatings ◽  
Content Type ◽  
Temperature Reduction ◽  
Insulation Effect

Purpose This paper aims to address the influence of diamond-like carbon (DLC) coatings on the frictional power loss of spur gears. It shows potentials for friction and bulk temperature reduction in industrial use. From a scientific point of view, the thermal insulation effect on fluid friction is addressed, which lowers viscosity in the gear contact due to increasing contact temperature. Design/methodology/approach Thermal insulation effect is analyzed in detail by means of the heat balance and micro thermal network of thermal elastohydrodynamic lubrication contacts. Preliminary results at a twin-disk test rig are summarized to categorize friction and bulk temperature reduction by DLC coatings. Based on experiments at a gear efficiency test rig, the frictional power losses and bulk temperatures of DLC-coated gears are investigated, whereby load, speed, oil temperature and coatings are varied. Findings Experimental investigations at the gear efficiency test rig showed friction and bulk temperature reduction for all operating conditions of DLC-coated gears compared to uncoated gears. This effect was most pronounced for high load and high speed. A reduction of the mean gear coefficient of friction on average 25% and maximum 55% was found. A maximum reduction of bulk temperature of 15% was observed. Practical implications DLC-coated gears show a high potential for reducing friction and improving load-carrying capacity. However, the industrial implementation is restrained by the limited durability of coatings on gear flanks. Therefore, a further and overall consideration of key durability factors such as substrate material, pretreatment, coating parameters and gear geometry is necessary. Originality/value Thermal insulation effect of DLC coatings was shown by theoretical analyses and experimental investigations at model test rigs. Although trial tests on gears were conducted in literature, this study proves the friction reduction by DLC-coated gears for the first time systematically in terms of various operating conditions and coatings. Peer review The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-07-2020-0257/

The Influence of Mounting Compliance and Operating Conditions on the Radial Stiffness of Ball Bearings: Analytic and Test Results

1991 ◽  
Author(s):  
M. F. Butner ◽  
B. T. Murphy ◽  
R. A. Akian
Keyword(s):  
Ball Bearing ◽  
Operating Conditions ◽  
Machine Design ◽  
Ball Bearings ◽  
Test Results ◽  
Resonant Frequencies ◽  
Analysis Process ◽  
Angular Deflection ◽  
Radial Stiffness ◽  
Bearing Stiffness

Abstract Ball bearing stiffness is significantly affected by internal clearance as well as the nature of applied loads and bearing ring mounting compliance. Since their stiffnesses are key to rotor critical speeds, it is important to obtain the most accurate possible radial stiffness prediction for shaft bearings during the machine design analysis process. Quasi-static analysis of spring-preloaded ball bearings predicted reduced radial stiffness when the outer ring is permitted to tilt rather than being assumed restrained from angular deflection. This effect was confirmed experimentally by observing resonant frequencies of a rotor supported on ball bearings of varied internal clearance, mounted with and without spring preloading. Analytic predictions of bearing stiffness are given, and test results presented for comparison.

Traction behaviours of aviation lubricating oil and the effects on the dynamic and thermal characteristics of high-speed ball bearings

2019 ◽  
Vol 72 (1) ◽  
pp. 15-23 ◽  
Author(s):  
Zhen Li ◽  
Yufan Lu ◽  
Chi Zhang ◽  
Jinlong Dong ◽  
Xiaoli Zhao ◽  
...  
Keyword(s):  
Dynamic Model ◽  
High Speed ◽  
Least Squares Method ◽  
Traction Force ◽  
Operating Conditions ◽  
Lubricating Oil ◽  
Ball Bearings ◽  
Content Type ◽  
Rapid Calculation ◽  
Synthetic Aviation

Purpose The traction behaviours of lubricating oil significantly affect the stability and lubrication regime of aviation high-speed ball bearings. Rolling elements will slide at a low traction force (TF). Therefore, traction behaviours need to be studied, and a fitting expression for traction curves to rapidly calculate the traction coefficient (TC) should be developed. Design/methodology/approach The traction behaviours of an aviation lubricating oil were studied in severe operating conditions with a self-designed two-disc testing rig. Based on the least squares method and the Levenberg–Marquardt theory, a rapid calculation expression was developed by fitting the obtained traction curves. The correction of this expression was experimentally verified by comparing the TCs under different operating conditions. This expression was also used to modify the commonly accepted quasi-dynamic model of rolling bearings. Findings An increase of the load led to an increase in the TC. In comparison, the temperature and entrainment speed showed inverse effects. The proposed expression exactly predicted the trend of the experimentally acquired traction curve. The calculation with the modified dynamic model showed that the action of the TF on a single rolling element varied and that the temperature increase of the outer raceway is higher than the inner raceway, which is caused by the TF and relative sliding speed between the elements and raceways. Originality/value The proposed fitting expression is able to simplify the TC calculation of synthetic aviation lubricating oil in practical engineering applications. This paper can provide an important reference for the traction behaviour of synthetic aviation lubricating oil under severe conditions and assist with its rapid calculation and practical application in engineering.

Ferrofluid lubrication for ball bearings to avoid starvation

2020 ◽  
Vol 72 (10) ◽  
pp. 1227-1231
Author(s):  
Mancheng Xu ◽  
Guanghu Jin ◽  
Qingwen Dai ◽  
Wei Huang ◽  
Xiaolei Wang
Keyword(s):  
Magnetic Field ◽  
Service Life ◽  
Peer Review ◽  
Design Methodology ◽  
Ball Bearing ◽  
Magnetic Circuit ◽  
Ball Bearings ◽  
Rolling Bearings ◽  
Content Type ◽  
Circuit Structure

Purpose This paper aims to prevent oil starvation and improve the service life of the rolling bearings. Design/methodology/approach A thrust ball bearing with magnetic circuit structure is proposed for ferrofluid lubrication. With the aid of magnetic field, ferrofluid can be maintained in the contact area of rolling bodies to delay lubricant loss. Experiments are performed to ensure the validity of the designed bearing. Findings Compared with conventional lubricant, service life of the ferrofluid lubricated bearing can be prolonged under magnetic field. In addition, with a proper magnetic field distribution, lubricant starvation may be limited under the conditions of present experiments. Originality/value This work provides a method to control the starved lubrication of rolling bearings with restricted lubricant supply. Peer review The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-04-2020-0132/

Research on the Influence of Clearance Variation on the Stiffness Fluctuation of Ball Bearing Under Different Operating Conditions

2020 ◽  
Vol 143 (2) ◽  
Author(s):  
Bin Fang ◽  
Shaoke Wan ◽  
Jinhua Zhang ◽  
Jun Hong
Keyword(s):  
Ball Bearing ◽  
Dynamic Performance ◽  
Research Work ◽  
Mathematic Model ◽  
Rotor System ◽  
Operating Conditions ◽  
Exploratory Research ◽  
Proposed Model ◽  
Bearing Stiffness ◽  
Control Hypothesis

Abstract The vibration induced by the varying compliance (VC) or the stiffness fluctuation of ball bearing plays a key role in the dynamic performance of the rotor system. The aim of this article is to study the stiffness fluctuation behaviors of ball bearing under different operating conditions. This article presents an improved mathematic model for ball bearing with wider applicability based on the new initial/reference position assumption and the ball-raceway contact/separation determination. The proposed model not only gets rid of the limitations of the raceway control hypothesis but also considers the space constraints of the cage on the balls. The advantages of the proposed model are presented through the typical working condition analysis, and the influences of the internal clearance on the stiffness and stiffness fluctuation of ball bearing under different operating conditions are given and discussed. The results show that bearing stiffness and stiffness fluctuation are determined by the external loads, rotating speeds, and internal clearances together, and properly increasing the axial load can effectively reduce the amplitudes and frequency components of the stiffness fluctuation. As an exploratory research work on the excitation source for the VC vibration of the bearing-rotor system, this article not only explains the complexity and diversity of the rotor VC vibration behavior from another side but also provides new ideas and important supplements for the rotor nonlinear analysis.

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