AN OVERLAY bearing is a bearing with a precision electroplated overlay of lead‐tin or lead‐indium alloy, 20 to 40µ thick. This lead‐alloy overlay is generally applied to a…
Abstract
AN OVERLAY bearing is a bearing with a precision electroplated overlay of lead‐tin or lead‐indium alloy, 20 to 40µ thick. This lead‐alloy overlay is generally applied to a copper‐lead or lead‐bronze substrate, which is itself bonded to a steel backing. Bearings of this construction are probably the most extensively used type of engine bearings; many millions are manufactured annually. The main functions of the overlay are to provide a seizure‐resistant surface, to increase the tolerance of the bearing for dirt and wear‐debris, and to protect the lead in the underlying copper‐lead or lead‐bronze alloy from corrosion by oxidized oil. When mineral oils are exposed to air oxidation for prolonged periods at elevated temperatures, weak organic acids are formed which can dissolve pure lead. The lead in copper‐lead or lead‐bronze is present as a separate, unalloyed phase, very susceptible to corrosion by weak organic acids. However, it has been known for some time that if lead is alloyed with indium or tin it is not corroded in this way. Most bearing manufacturers incorporate at least 4%w indium or 8%w tin in overlays to make them resistant to corrosion, but precise information on the amounts of alloying element required is not available.
Matteo Perini and Alessia Teresa Silvestri
This study aims to manufacture bimetallic bearings by achieving a sound deposition of bronze. Indeed, systems with rotating components use parts that reduce friction by allowing…
Abstract
Purpose
This study aims to manufacture bimetallic bearings by achieving a sound deposition of bronze. Indeed, systems with rotating components use parts that reduce friction by allowing them to rotate freely. This is typically achieved with either rolling bearings or plain bearings. The last ones are usually made of self-lubricating materials, which may not excel in mechanical properties. An interesting alternative lies in bimetallic brass bearings, like bronze-steel combinations. However, they are limited in terms of available shapes and sizes due to challenges associated with the conventional manufacturing process.
Design/methodology/approach
This study addresses the problems of mechanical weakness and production limitations of conventional brass bearings by introducing the use of Hybrid Manufacturing techniques: Laser Directed Energy Deposition technology in combination with five-axis milling. Specifically, Cu89Sn11 was deposited on a C45 substrate by varying the number of layers, and based on the results obtained, two kinds of bimetallic bearings were produced.
Findings
The results of the one, two and five-layers samples indicate a sound deposition of Cu89Sn11, without defects such as detachments, cracks or porosities. The microhardness profile shows a decreasing trend from the substrate to the deposition zones. Bending and adhesion tests confirmed the excellent material bonding. Five-layers of Bronze were deposited on a C45 substrate to fabricate hemispherical and flat-face bearings.
Originality/value
This study validates the feasibility of expanding the new class of 3D-printed high-performance materials, highlighting the advantages of additive manufacturing technologies, such as the design and material mixing freedom, by manufacturing two kinds of bimetallic bearings.
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A well‐established syllabus of fourteen 90‐minutes lecture sessions, over five days, plus practical laboratory demonstrations and discussion (to say nothing of first‐class evening…
Abstract
A well‐established syllabus of fourteen 90‐minutes lecture sessions, over five days, plus practical laboratory demonstrations and discussion (to say nothing of first‐class evening entertainment), produced a full house for this year's Industrial Tribology Seminar at Swansea (September 16–20).
Jianfei Yu, Li Jiang and Fuxing Gan
This paper aims to study the corrosion behavior of carbon steel and stainless steel in white oil with naphthenic acid under high temperature.
Abstract
Purpose
This paper aims to study the corrosion behavior of carbon steel and stainless steel in white oil with naphthenic acid under high temperature.
Design/methodology/approach
The weight‐loss method and surface analysis were used to study the corrosion behavior of steel in white oil with naphthenic acid.
Findings
Naphthenic acids corrosion rates were directly related to experimental temperature, immersion time and total acid number (TAN). The activation energy was calculated and the process kinetics could be represented by Arrhenius‐type equation. The relationship between the isothermal line in liquid phase and that in vapor phase at different TAN values had a significant distinction with the change of temperature.
Originality/value
The findings have important implications for assessing the corrosivity of crude oils with high TAN value from various resources.
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M. Amalia Pesantes and Patricia I. Documet
The purpose of this paper is to describe and discuss the limitations of strategies that mothers of undocumented Latino children use in an emerging community to address the health…
Abstract
Purpose
The purpose of this paper is to describe and discuss the limitations of strategies that mothers of undocumented Latino children use in an emerging community to address the health needs of their children.
Design/methodology/approach
In-depth interviews with low-income immigrant mothers of undocumented Latino children (n=10) and social service providers (n=6). Interviews were transcribed, coded using Atlas-ti and analyzed to identify common perspectives on the strategies used to secure healthcare for uninsured undocumented children.
Findings
Mothers of undocumented Latino children struggle to secure healthcare for their children. Based on the principles of familismo and personalismo, they rely on social support networks such as friends, relatives and fellow churchgoers to secure information about available healthcare options. Despite the willingness of social and health service providers to help them access healthcare, options are limited and depend on the actions of individuals rather than organized solutions. Securing care for undocumented children using families, friends and sympathetic individual providers as the source of information and advice leads to fragile unsustainable solutions.
Research limitations/implications
This paper adds to the small yet growing literature of Latinos in emerging communities.
Practical implications
Emerging Latino communities are usually unprepared to welcome Latinos and address its various needs. Undocumented children are a particularly vulnerable group and any sustainable strategy to address their needs would require structural changes in existing health services to ensure that undocumented children’s lives are not affected by poor health.
Originality/value
Healthcare access problems for immigrant children are presented from the perspective of parents and offers a nuanced description of health systems unpreparedness to provide care for vulnerable groups whose immigrant status is poorly understood.
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This paper aims to uncover how social media is used, managed, and perceived by sports and entertainment venue (SEV) managers. While there is considerable evidence that social…
Abstract
Purpose
This paper aims to uncover how social media is used, managed, and perceived by sports and entertainment venue (SEV) managers. While there is considerable evidence that social media has been used effectively by Fortune 500 companies, it is not known how social media is administered and perceived among managers of arenas, stadiums, performing art centers, and convention centers.
Design/methodology/approach
This paper used survey methodology to capture the perceptions of 383 venue management professionals, all members of the International Association of Venue Managers (IAVM).
Findings
Most venue managers feel their social media efforts are proficient or at the expert level and most have a defined social media strategy. Others feel much less confident about their social media efforts and have no defined social media strategy. At a statistically significant level, those with a defined social media strategy report increased revenue, while those without a defined social media strategy do not. Venue managers forecast a significant increase in non‐traditional marketing strategies while using traditional marketing efforts over the next three years far less.
Research limitations/implications
While the 383 responders are IAVM active members who are in venue management, they reasonably represent SEV managers in general and these survey results can be generalized to SEV managers with an overall conservative margin of error of ±5.0 percent at the 95 percent confidence level. The survey was conducted online by e‐mail invitation. While using the online media to deliver a survey related to the proliferation of various online activities was, at one time, questionable and, potentially, a source of responder bias, the current level of saturation of e‐mail use by and comfort with online activity of professionals mitigates these likely sources of responder bias and is not a source of additional concern with this study.
Practical implications
The paper concludes with a discussion of the results and a recommendation that venue managers define a social media strategy that includes hiring or reassigning staff to support this important area of social media marketing.
Originality/value
This paper is unique in that examines social media use in the unique context of SEVs.
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Ding‐Rong Qu, Yu‐Gui Zheng, Xiu Jiang and Wei Ke
The objective of the present work was to study the influence of chemical compositions of five naphthenic acids (NAs) extracted from Liaohe crude oil on their corrosivity.
Abstract
Purpose
The objective of the present work was to study the influence of chemical compositions of five naphthenic acids (NAs) extracted from Liaohe crude oil on their corrosivity.
Design/methodology/approach
Fourier‐transform infrared spectrometry and electron impact mass spectrometry were used to characterize the chemical structures and compositions if five NAs. The corrosivities of the NAs were assessed by stagnant NA corrosion (NAC) tests. An attempt was made to identify any correlation between the chemical composition of the NAs and their corrosiveness.
Findings
The acidic species in all five NA samples were saturated aliphatic and naphthenic acids and the amount of aromatic and unsaturated acids was negligible. A relationship between the carboxylic acid distribution and the molecular weight was obtained. Most of the carboxylic acids in five NAs contained 0‐3 ring structures. NAs with lower molecular weight and fewer ring structures usually were more corrosive.
Originality/value
The findings have important implications for assessing the corrosivity of acidic crude oils from various resources.
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IT is difficult to imagine the world of Work Study without the urbane ubiquity of Russell Currie, whose death on 28 August we deeply regret to record. Although he had been…
Abstract
IT is difficult to imagine the world of Work Study without the urbane ubiquity of Russell Currie, whose death on 28 August we deeply regret to record. Although he had been officially in retirement for a year or two his presence was immanent in any important gathering of those who had so long looked to him for the leadership that was always forthcoming. We can fittingly borrow an epigram he coined at the London Congress in 1963 as apt at this time. ‘The sun shone to greet your arrival; the skies weep for your departure.’
The literature discusses “internal balance” and “external balance” (hereafter labelled IB and XB respectively) as if they are clearly defined concepts. If an economy is to achieve…
Abstract
The literature discusses “internal balance” and “external balance” (hereafter labelled IB and XB respectively) as if they are clearly defined concepts. If an economy is to achieve IB or XB or both then it must know what it is trying to achieve! In addition, this begs the question of precisely who it is that is achieving the stated objectives. Is it the government? Is it some decentralised decision unit, like the Treasury or the Bank of England? Furthermore what has been said so far presupposes that IB and XB are definitely objectives rather than constrainsts. If we suppose for the moment that XB means balance of payments equilibrium (yet to be defined), then some would argue that this is not an objective but rather a constraint. We shall not enter this debate here and treat XB as an objective.
THE responsibility for materials handling methods, as for all other production methods, should be made the clear responsibility of the head of Work Study. The reasoning behind…
Abstract
THE responsibility for materials handling methods, as for all other production methods, should be made the clear responsibility of the head of Work Study. The reasoning behind that firm conclusion is very logical. Industry in general depends for its success upon the application of some process such as machining or finishing of raw materials. Every such operation adds to its value and builds up a firm's turnover. It is therefore obvious that the more time there is devoted to conversion the less will be wasted on profitless storage or unproductive transport from one part of the works to another.