The influence of surface roughness and viscosity on micropitting damage

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Wei Li ◽  
Liantao Lu
Keyword(s):  
Surface Roughness ◽  
Boundary Lubrication ◽  
Design Methodology ◽  
Wear Loss ◽  
Range Analysis ◽  
Heavy Load ◽  
Content Type ◽  
Two Factors ◽  
Lubrication Condition ◽  
Laser Confocal Microscope

Purpose This study aims to investigate the influence of surface roughness and viscosity on micropitting and their influence sequence. Design/methodology/approach Specimens were made of carburized and quenched 18CrNiMo7-6, and different surface roughness was obtained by grinding and shot peening. Tests were carried out on a rolling-sliding tribometer, with different viscosity lubricants and a heavy load under a boundary lubrication condition. The laser confocal microscope was used to measure the aspects, surface roughness, profiles in the contacted region and micropitting damage percentage. A factorial experiment was designed, and the range analysis was applied to find the sequence of influence of surface roughness and viscosity. Findings The result shows that surface roughness has a more noticeable influence since the change of viscosity cannot generate sufficient wear loss to suppress micropitting. Originality/value The influence sequence of two factors on micropitting was investigated and the reason for the distribution was analyzed.

A scuffing model considering additive depletion in boundary lubrication

2019 ◽  
Vol 72 (3) ◽  
pp. 267-272
Author(s):  
Bora Lee ◽  
Yonghun Yu ◽  
Yong-Joo Cho
Keyword(s):  
Boundary Lubrication ◽  
Mass Conservation ◽  
Additive Concentration ◽  
Contact Conditions ◽  
Sliding Bearings ◽  
Content Type ◽  
Proposed Model ◽  
Lubrication Condition ◽  
Scuffing Failure ◽  
Sliding Distance

Purpose This paper aims to propose a new scuffing model caused by the depletion of additives in boundary lubrication condition. Design/methodology/approach The differential equation governing the distribution of additive content in the fluid film was used. This formula was derived from the principle of mass conservation of additives considering the consumption due to surface adsorption of wear particles. The occurrence of scuffing was determined by comparing the wear rate of the oxide layer with the oxidation rate. Findings If the additive becomes depleted while sliding, the scuffing failure occurs even at a low-temperature condition below the critical temperature. The critical sliding distance at which scuffing failure occurred was suggested. The experimental data of the existing literature and the theoretical prediction using the proposed model are shown to be in good agreement. Originality/value It is expected to be used in the design of oil supply grooves for sliding bearings operating under extreme conditions or in selecting the minimum initial additive concentration required to avoid scuffing failure under given contact conditions.

scholarly journals Development and validation of the Work Environment Complexity Scale for leaders

2019 ◽  
Vol 32 (2) ◽  
pp. 296-308 ◽  
Author(s):  
Teresa Bezler ◽  
Giovanni B. Moneta ◽  
Gary Pheiffer
Keyword(s):  
Work Environment ◽  
Design Methodology ◽  
Work Demands ◽  
Frequent Change ◽  
Cross Sectional ◽  
Content Type ◽  
Two Factors ◽  
Leadership Research ◽  
Development And Validation ◽  
Practical Implications

Purpose The purpose of this paper is to develop and validate a Work Environment Complexity (WEC) Scale for leaders. Design/methodology/approach The paper uses both cross-sectional and longitudinal data, gathered in the course of major organisational restructuring, using samples from employees (n=305) and leaders (n=120) in two health care organisations. Findings The research developed and validated a scale of WEC for leaders with two factors: frequent change and events, and uncertain work demands. Comparisons between samples suggest diverging employee and leadership representations of WEC. Practical implications Being the first scale to measure the comprehensive construct of WEC, a foundation is laid to measure the amount of complexity in a leader’s work and the functioning of leaders with regards to WEC. Originality/value This paper contributes to leadership research and practice by clarifying the construct of WEC for leaders empirically and validating a bidimensional scale of WEC.

Innovation strategies in the Brazilian sugar–energy industry

2019 ◽  
Vol 9 (5) ◽  
pp. 536-551 ◽  
Author(s):  
Samara Marques Gomes ◽  
David Ferreira Lopes Santos ◽  
Leonardo Fernando Cruz Basso
Keyword(s):  
Design Methodology ◽  
Energy Industry ◽  
Southern Brazil ◽  
Content Type ◽  
Management Of Resources ◽  
Two Factors ◽  
Innovation Strategies ◽  
Energy Companies ◽  
Implementation Of Innovations ◽  
Practical Implications

Purpose The purpose of this paper is to analyze the innovation strategies of the sugar–energy industry in Central-Southern Brazil with regard to its resource structure and results. Design/methodology/approach The data were collected through a questionnaire covering the three-year period from 2015 through 2017. The results were extracted based on a combination of factor analysis and multiple regression analysis. Findings The innovation strategies of Brazilian sugar–energy companies are characterized as defensive and imitative based on the resources dedicated to innovation and the implementation of innovation with respect to products, processes, eco-innovation and cost reductions. Research limitations/implications The sample is representative, but it does not cover all companies in the Brazilian sugar–energy industry. The data were acquired using a survey, and the results could not be compared to the financial results of the companies. Practical implications Sugar–energy companies need to define their innovation strategies, as these strategies lead to different results that can be achieved only through the management of resources dedicated to the generation and implementation of innovations. Managers and analysts need to know the profile of these innovation strategies to evaluate the effectiveness of the results based on the resources that were invested. Originality/value This study presents an exploratory model that identified two factors related to innovation efforts and three results. It is possible to define the innovation strategies of companies in the Brazilian sugar–energy industry, which is one of the most competitive in Brazil.

The effect of EBM process parameters upon surface roughness

2016 ◽  
Vol 22 (3) ◽  
pp. 495-503 ◽  
Author(s):  
Rebecca Klingvall Ek ◽  
Lars-Erik Rännar ◽  
Mikael Bäckstöm ◽  
Peter Carlsson
Keyword(s):  
Surface Roughness ◽  
Electron Beam ◽  
Surface Properties ◽  
Process Parameters ◽  
Electron Beam Melting ◽  
Design Methodology ◽  
New Materials ◽  
Content Type ◽  
Melt Pool ◽  
Practical Implications

Purpose The surface roughness of products manufactured using the additive manufacturing (AM) technology of electron beam melting (EBM) has a special characteristic. Different product applications can demand rougher or finer surface structure, so the purpose of this study is to investigate the process parameters of EBM to find out how they affect surface roughness. Design/methodology/approach EBM uses metal powder to manufacture metal parts. A design of experiment plan was used to describe the effects of the process parameters on the average surface roughness of vertical surfaces. Findings The most important electron beam setting for surface roughness, according to this study, is a combination of “speed and current” in the contours. The second most important parameter is “contour offset”. The interaction between the “number of contours” and “contour offset” also appears to be important, as it shows a much higher probability of being active than any other interaction. The results show that the “line offset” is not important when using contours. Research limitations/implications This study examined “contour offset”, “number of contours”, “speed in combination with current” and “line offset”, which are process parameters controlling the electron beam. Practical implications The surface properties could have an impact on the product’s performance. A reduction in surface processing will not only save time and money but also reduce the environmental impact. Originality/value Surface properties are important for many products. New themes containing process parameters have to be developed when introducing new materials to EBM manufacturing. During this process, it is very important to understand how the electron beam affects the melt pool.

Investigations on influence of groove shapes for the journal bearing in high-speed and heavy-load press system

2018 ◽  
Vol 70 (1) ◽  
pp. 230-240 ◽  
Author(s):  
Yu Chen ◽  
Yu Sun ◽  
Chunping Cao
Keyword(s):  
High Speed ◽  
Design Methodology ◽  
Journal Bearing ◽  
Computational Method ◽  
Hydrodynamic Characteristics ◽  
Hydrodynamic Behavior ◽  
Heavy Load ◽  
Content Type ◽  
Thermal Influence ◽  
Fluid Interaction

Purpose The purpose of this study is to investigate the hydrodynamic characteristics of journal bearings in a high-speed and heavy-load press system by considering thermal influence and cavitation. Design/methodology/approach A proper and effectual computational method is presented for steady-state analysis of fluid interaction in a rotor-bearing press system by combining computational fluid dynamics techniques. Findings The influences of eccentricity ratio, rotational speed and oil-film thickness on the hydrodynamic behavior of the journal bearing are studied. Originality/value The computational method can be used for creating a precise lubrication design for a journal bearing of a lubrication system.

Investigation of wear mechanism of forged steel piston skirt under boundary lubricated conditions

2018 ◽  
Vol 70 (7) ◽  
pp. 1303-1309
Author(s):  
Zhang Jian ◽  
Deng Lijun ◽  
Hao Guannan ◽  
Liu Shiying
Keyword(s):  
Surface Roughness ◽  
Wear Mechanism ◽  
Boundary Lubrication ◽  
Normal Load ◽  
Testing Machine ◽  
Wear Model ◽  
Content Type ◽  
Piston Skirt ◽  
Steel Piston ◽  
Lubrication Conditions

Purpose With the implementation of new emission standards, the thermal–mechanical coupling load of engine pistons becomes more important. In this case, forged steel material with higher fatigue limit and impact resistance has been applied gradually in piston manufacturing. However, new failure problems emerge, and the wear of skirt under boundary lubrication conditions is an essential problem which needs to be solved urgently. Design/methodology/approach In this research, the abrasion testing machine was used to simulate the wear behavior under different conditions of normal pressure, relative velocity and surface roughness. Besides, the wear morphology was observed by scanning electron microscope. Then, the wear model was established by using test results fitting method, offering a way to conduct qualitative analysis for the wear problem under the same conditions. Findings The results show that mainly the wear mechanism of the piston skirt under boundary lubricated conditions is adhesive wear and abrasive wear. In addition, the coefficient and wear rate will increase with the increase in the normal load and surface roughness and decrease with the increase in the relative speed. In the wear model, the wear loss is mainly influenced by the normal load, the relative sliding speed and the wear time. Originality/value The wear degree of piston skirt was qualitatively obtained in this investigation by factors such as pressure, velocity and so on, and the wear mechanism of forged steel piston skirt under boundary lubrication conditions was also determined. These could provide theoretical support for further optimization of cylinder motion and oil supply system, reduction of friction loss and power loss.

Face of CEO in corporate publicity affects viewer regard for the firm

2019 ◽  
Vol 37 (1) ◽  
pp. 21-30
Author(s):  
Dwane H. Dean
Keyword(s):  
Design Methodology ◽  
Downside Risk ◽  
Facial Image ◽  
Content Type ◽  
Multiple Factors ◽  
Two Factors ◽  
The Media ◽  
Positive Feelings ◽  
Corporate Merger

Purpose The purpose of this paper is to investigate the ability of head-and-shoulder photos of CEOs appearing in a publicity item to influence reader regard for the corporation linked to the CEO. Design/methodology/approach Study 1 investigated three factors, face of a male CEO (trustworthy versus less trustworthy), headline framing of a corporate merger (tax-dodge vs specialization strategy) and respondent gender, whereas Study 2 explored two factors, face of a CEO (male vs female) and headline framing. The primary dependent variable was respondent regard for the firm. Findings Study 1 resulted in a significant three-way interaction. Face of a male CEO moderated a two-way interaction between the gender and the headline. Women, as compared with men, responded particularly unfavorably to the combination of an untrustworthy face and a tax-dodge headline. In Study 2, a firm headed by a male CEO and engaged in a tax-dodge action was poorly regarded, whereas a firm headed by a female CEO pursuing the same action did not suffer a loss of regard. Research limitations/implications Only one framing device (headlines) was studied when there are multiple such devices. Also, overall regard for the firm is influenced by multiple factors. Originality/value Of the factors investigated (facial image, headline and reader gender), only one is controlled by the corporation – the image of the spokesperson presented to the media. Findings suggest less downside risk to reputation if the company uses only trustworthy-looking spokespersons. Also, a female CEO may be a reputational asset. Women reported significantly more positive feelings toward a corporation headed by a female CEO than a male CEO.

scholarly journals Robotic additive manufacturing system for dynamic build orientations

2020 ◽  
Vol 26 (4) ◽  
pp. 659-667
Author(s):  
Nicholas R. Fry ◽  
Robert C. Richardson ◽  
Jordan H. Boyle
Keyword(s):  
Surface Roughness ◽  
Additive Manufacturing ◽  
Design Methodology ◽  
Degrees Of Freedom ◽  
Manufacturing System ◽  
Print Quality ◽  
Orientation Relationships ◽  
Fused Filament Fabrication ◽  
Content Type ◽  
Build Orientation

Purpose This paper aims to present a multi-axis additive robot manufacturing system (ARMS) and demonstrate its beneficial capabilities. Design/methodology/approach ARMS was constructed around two robot arms and a fused filament fabrication (FFF) extruder. Quantitative experiments are conducted to investigate the effect of printing at different orientations with respect to gravity, the effect of dynamically changing build orientation with respect to the build tray when printing overhanging features, the effect of printing curved parts using curved, conformal layers. These capabilities are combined to print an integrated demonstrator showing potential practical benefits of the system. Findings Orientation with respect to gravity has no effect on print quality; dynamically changing build orientation allows overhangs up to 90° to be cleanly printed without support structures; printing an arch with conformal layers significantly increases its strength compared to conventional printing. Research limitations/implications The challenge of automatic slicing algorithms has not been addressed for multi-axis printing. It is shown that ARMS could eventually enable printing of fully-functional prototypes with embedded components. Originality/value This work is the first to prove that the surface roughness of an FFF part is independent of print orientation with respect to gravity. The use of two arms creates a novel system with more degrees of freedom than existing multi-axis printers, enabling studies on printing orientation relationships and printing around inserts. It also adds to the emerging body of multi-axis literature by verifying that curved layers improve the strength of an arch which is steeply curved and printed with the nozzle remaining normal to the curvature.

Simultaneous extraction of profile and surface roughness of 3D SLM components using fringe projection method

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Terry Yuan-Fang Chen ◽  
Yu-Lung Lo ◽  
Ze-Hong Lin ◽  
Jui-Yu Lin
Keyword(s):  
Surface Roughness ◽  
Metal Powder ◽  
Design Methodology ◽  
Melting Process ◽  
Phase Unwrapping ◽  
Fringe Projection ◽  
Laser Melting ◽  
Height Difference ◽  
Content Type ◽  
Detection Technology

Purpose The purpose of this study was expected to simultaneously monitor the surface roughness of each solidified layer, the surface roughness of the metal powder, the outline of the solidified layer, and the height difference between the solidified layer and the metal powder. Design/methodology/approach In the proposed approach, color images with red, green and blue fringes are used to measure the shape of the built object using a three-step phase-shift algorithm and phase-unwrapping method. In addition, the surface roughness is extracted from the speckle information in the captured image using a predetermined autocorrelation function. Findings The feasibility and accuracy of the proposed system were validated by comparing it with a commercial system for an identical set of samples fabricated by a selective laser melting process. The maximum and minimum errors between the two systems are approximately 24% and 0.8%, respectively. Originality/value In the additive manufacturing field, the authors are the first to use fringe detection technology to simultaneously measure the profile of the printed layer and its surface roughness.

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