Lubrication Research Papers - Academia.edu (original) (raw)

Genital tract trauma following spontaneous vaginal childbirth is common, and evidence-based prevention measures have not been identified, beyond minimizing the use of episiotomy. This study randomized 1211 healthy women in midwifery care... more

Genital tract trauma following spontaneous vaginal childbirth is common, and evidence-based prevention measures have not been identified, beyond minimizing the use of episiotomy. This study randomized 1211 healthy women in midwifery care at the University of New Mexico teaching hospital to one of three care measures late in the second stage of labor:1) warm compresses to the perineal area, 2) massage with lubricant, or 3) no touching of the perineum until crowning of the infant's head. The purpose was to assess whether any of these measures was associated with lower levels of obstetric trauma. After each birth, the clinical midwife recorded demographic, clinical care, and outcome data, including the location and extent of any genital tract trauma. The frequency distribution of genital tract trauma was equal in all three groups. Individual women and their clinicians should decide whether to use these techniques based on maternal comfort and other considerations. . precis: Selected midwifery strategies for management of the perineum in childbirth (warm compresses, massage with lubricant, or hands off until crowning) were not associated with more or fewer spontaneous lacerations.

The aeration of an oil film flowing between the faces of two closely spaced circular plates (one stationary, and one rotating) is examined experimentally, numerically, and with an improved lubrication model. The gap between the plates is... more

The aeration of an oil film flowing between the faces of two closely spaced circular plates (one stationary, and one rotating) is examined experimentally, numerically, and with an improved lubrication model. The gap between the plates is small compared to their radii, making lubrication theory appropriate for modeling the flow. However, standard lubrication boundary conditions suggested by Reynolds (1886, "On the Theory of Lubrication and its Application to Mr. Beauchamp Tower’s Experiments, Including an Experimental Determination of the Viscosity of Olive Oil," Philos. Trans. R. Soc. London, 177, pp. 157-234) of p = 0 and pn = 0 (Dirichlet and Neumann conditions on pressure) at the gas-liquid interface do not allow for the inclusion of a contact line model, a phenomenon that is important in the inception of aeration. Hence, the standard theory does not adequately predict the experimentally observed onset of aeration. In the present work, we modify the Neumann boundary con...

Lubrication of mammalian joints is mediated by lubricin, a product of megakaryocyte stimulating factor gene (MSF; GenBank accession #U70136) expression. Lubricin (M(r) approximately 240 kDa) is a mucinous glycoprotein which is 50% (w/w)... more

Lubrication of mammalian joints is mediated by lubricin, a product of megakaryocyte stimulating factor gene (MSF; GenBank accession #U70136) expression. Lubricin (M(r) approximately 240 kDa) is a mucinous glycoprotein which is 50% (w/w) post-translationally modified with beta(1-3)Gal-GalNAc incompletely capped with NeuAc, and lubricates apposed cartilaginous surfaces in the boundary mode through an unknown mechanism. Both bovine and human lubricin were purified from synovial fluid and digested with recombinant glycosidases. Released oligosaccharides were identified and quantified by fluorophore assisted carbohydrate electrophoresis (FACE). Corresponding digests of human lubricin were also assayed in a friction apparatus oscillating latex rubber against polished glass at a pressure of 0.35 x 10(6) N/m(2) and the coefficient of friction (mu) was measured. Digestion with alpha2,3-neuraminidase decreased lubricating ability by 19.3%. Partial removal of beta(1-3)Gal-GalNAc moieties by en...

Lubricant accumulation on the slider's surface of a hard disk drive (HDD) has a detrimental effect on its read/write performance. Air flow through the slider-disk clearance moves some of the lubricant from the air-bearing surface (ABS)... more

Lubricant accumulation on the slider's surface of a hard disk drive (HDD) has a detrimental effect on its read/write performance. Air flow through the slider-disk clearance moves some of the lubricant from the air-bearing surface (ABS) toward the slider's lateral walls where it accumulates. In this article, we show by numerical simulations that the lubricant accumulation characteristics are strongly dependent on the slider's flying height, skew angle and ABS design. The lubricant flow on the slider's surface is quantified numerically. Air shear stress, air pressure and disjoining pressure are used as driving forces in the simulations. The lubricant thickness profile and volume evolution are calculated for two states of the HDD: operating and at rest. In the first state, lubricant is driven by air shear stress toward the trailing edge of the slider where it accumulates on the deposit end. In the second state, lubricant from the deposit end flows back into the ABS driven by the action of disjoining pressure. Lubricant accumulation on the four lateral walls of the slider is taken into account. The lateral walls are unfolded to study the flow using a two-dimensional lubrication model. The effects of flying height, skew angle and slider design on the accumulation removal of lubricant from the ABS are determined for the two states of the drive. Keywords Air bearings Á Lubricant transfer Á Head–disk interface Á Hard disk drive

The rolling process had been used in every aspect of our life. Various types of sections like tee, angle, channel, railway track, sheets, foils of different mate-rial are made by rolling process. The quality of the product depends upon... more

The rolling process had been used in every aspect of our life. Various types of sections like tee, angle, channel, railway track, sheets, foils of different mate-rial are made by rolling process. The quality of the product depends upon the various characteristics of rolling parameters. At the junction, the key role played by lubricants for saving energy and properties of the material in contact. Re-searchers are putting continuous efforts into the tribological analysis and developing new lubricants for the rolling process according to the material. The authors had reviewed the lubricants used in different rolling processes and found out a diverse range of lubricants. Various ecologically safe and effective lubricants had been reviewed. Lubrication performance testing tribometer for testing of tribological properties of lubricants had been reviewed. Hydrodynamic, mixed and boundary lubrication mechanisms had been found in different rolling conditions. The use of lubricants was found ...

There are increasing pressures upon the automotive industry to reduce harmful emissions as well as meeting the key objective of enhanced fuel efficiency, while improving or retaining the engine output power. The losses in an internal... more

There are increasing pressures upon the automotive industry to reduce harmful emissions as well as meeting the key objective of enhanced fuel efficiency, while improving or retaining the engine output power. The losses in an internal combustion (IC) engine can be divided into thermal and parasitic as well as due to gas leakage because of untoward compression ring motions. Frictional losses are particularly of concern at low engine speeds, assuming a greater share of the overall losses. Piston–cylinder system accounts for nearly half of all the frictional losses. Loss of sealing functionality of the ring pack can also contribute significantly to power losses as well as exacerbating harmful emissions. The dynamics of compression ring is inexorably linked to its tribological performance, a link which has not been made in many reported analyses. A fundamental understanding of the interplay between the top compression ring three-dimensional elastodynamic behavior, its sealing function an...

This paper proposes a new methodology for detecting and diagnosing faults found in heavy duty diesel engines based upon spectrometric analysis of lubrication samples, and is compared against a conventional method, redline limits, which is... more

This paper proposes a new methodology for detecting and diagnosing faults found in heavy duty diesel engines based upon spectrometric analysis of lubrication samples, and is compared against a conventional method, redline limits, which is utilised in a number of major laboratories in the UK and across Europe. The proposed method applies computational power to a well known maintenance technique, and consists of an improved method of preprocessing to form a derivative tuple, which extracts further information from the measured elemental concentrations. To identify incipient faults, the distance in vector space is calculated using a Gaussian contour, generated from prior data, as the zero crossing, which enables novel samples to be classified as normal or abnormal. This information is utilised as the input to a probabilistic directed acyclic graph in the form of a belief network. This network provides a prognosis for the mechanism as well as suggesting possible actions that could be taken to rectify the diagnosed problem, supported with confidence probabilities. The proposed method is evaluated for both accuracy in detecting a fault, as well as the duration of time that is provided before the event occurs, with significant improvements in both metrics demonstrated over the conventional method.

Optimization of process parameters in sheet metal forming is an important task to reduce manufacturing cost. To determine the optimum values of the process parameters, it is essential to find their influence on the deformation behaviour... more

Optimization of process parameters in sheet metal forming is an important task to reduce manufacturing cost. To determine the optimum values of the process parameters, it is essential to find their influence on the deformation behaviour of the sheet metal. The significance of three important process parameters namely, die radius, blank holder force and friction coefficient on the deep-drawing characteristics of a stainless steel axi-symmetric cup was determined. Finite element method combined with Taguchi technique form a refined predictive tool to determine the influence of forming process parameters. The Taguchi method was employed to identify the relative influence of each process parameter considered in this study. A reduced set of finite element simulations were carried out as per the Taguchi orthogonal array. Based on the predicted thickness distribution of the deep drawn circular cup and analysis of variance test, it is evident that die radius has the greatest influence on the deep drawing of stainless steel blank sheet followed by the blank holder force and the friction coefficient. Further, it is shown that a blank holder force application and local lubrication scheme improved the quality of the formed part.

Friction measurements of articular cartilage are important to determine the relative tribologic contributions made by synovial fluid or cartilage, and to assess the efficacy of therapies for preventing the development of post-traumatic... more

Friction measurements of articular cartilage are important to determine the relative tribologic contributions made by synovial fluid or cartilage, and to assess the efficacy of therapies for preventing the development of post-traumatic osteoarthritis. Stanton's equation is the most frequently used formula for estimating the whole joint friction coefficient (m) of an articular pendulum, and assumes pendulum energy loss through a mass-independent mechanism. This study examines if articular pendulum energy loss is indeed mass independent, and compares Stanton's model to an alternative model, which incorporates viscous damping, for calculating m. Ten loads (25-100% body weight) were applied in a random order to an articular pendulum using the knees of adult male Hartley guinea pigs (n ¼4) as the fulcrum. Motion of the decaying pendulum was recorded and m was estimated using two models: Stanton's equation, and an exponential decay function incorporating a viscous damping coefficient. m estimates decreased as mass increased for both models. Exponential decay model fit error values were 82% less than the Stanton model. These results indicate that m decreases with increasing mass, and that an exponential decay model provides a better fit for articular pendulum data at all mass values. In conclusion, inter-study comparisons of articular pendulum m values should not be made without recognizing the loads used, as m values are mass dependent.

Lubricating oils are undergoing more changes today than at any time in recent memory. This has been driven by the switch to more advanced base stocks which require new additive chemistries, along with increased equipment performance... more

Lubricating oils are undergoing more changes today than at any time in recent memory. This has been driven by the switch to more advanced base stocks which require new additive chemistries, along with increased equipment performance duties and extreme lubricant operating conditions. These are among the factors that have contributed to the emerging problem of lubricant 'varnish' deposits caused by oil degradation. Varnish is a sticky residue that leads to valve malfunction, blocked fl ow lines, premature fi lter blockage, increased bearing friction, nuisance oil leaks etc. All of which are leading to reliability problems across many industries. This article highlights how lubricant varnish is formed, what problems it can cause and how to test the new generation oils for their tendency to form varnish deposit. It will then discuss the proactive methods and technologies available for solving varnish deposit problems.

The mating threaded surfaces of the implant should be well lubricated when tightening an abutment screw. By using torque control and a tightening torque greater than that recommended, it is possible to increase the preload beyond that... more

The mating threaded surfaces of the implant should be well lubricated when tightening an abutment screw. By using torque control and a tightening torque greater than that recommended, it is possible to increase the preload beyond that allowed by surface lubrication alone in order to achieve the desired range of preload. Statement of problem. Screw loosening is a problem for a percentage of implants. A probabilistic analysis to determine the cumulative probability distribution of the preload, the probability of obtaining an optimal preload, and the probabilistic sensitivities identifying important variables is lacking.

The tribological performance of piston rings in reciprocating internal combustion engines can only be fully understood when both lubrication and wear are considered in combination. To this end, a numerical model has been developed that... more

The tribological performance of piston rings in reciprocating internal combustion engines can only be fully understood when both lubrication and wear are considered in combination. To this end, a numerical model has been developed that predicts the dynamics, lubrication and wear of piston rings interactively for the first time. This paper reports the application of this new model to the piston ring pack of a diesel engine. With the overall aim of evaluating the correlation between theory and experiments, this analysis is divided into two discrete parts. First, the model is used to predict the lubrication performance of measured ring packs before and after periods of running, at constant speed and load, in a Caterpillar 1Y73 single-cylinder diesel engine: the objective being to establish the change in tribological behaviour with observed wear in the engine. Secondly, the model is used interactively to predict the lubrication and wear of the top compression ring from the same engine. This research advances the understanding of piston ring profile evolution with time and its dependence on complex interactions between lubrication and wear. q 1999 Elsevier Science S.A. All rights reserved.

Xerostomia is a relatively common complaint that can make the wearing of dentures very uncomfortable for affected individuals. To help overcome this problem, a number of techniques have been proposed for incorporating reservoirs,... more

Xerostomia is a relatively common complaint that can make the wearing of dentures very uncomfortable for affected individuals. To help overcome this problem, a number of techniques have been proposed for incorporating reservoirs, containing salivary substitutes, into dentures. These have had varying degrees of success. This paper presents a case of a patient suffering from xerostomia who was successfully treated with a new form of reservoir denture. This new split-denture technique resulted in a reservoir denture that provided good lubrication of the oral tissues, was easily cleaned by the wearer and was produced from routine denture materials. Details of its design, construction and other potential applications are also presented. Fig 7. A wire demonstrates the reservoir drainage hole in the inferior aspect of the lingual flange.

Introduction. Although studies of specific groups of individuals (e.g., adolescents, "high risk" samples) have examined sexual repertoire, little is known, at the population level, about the sexual behaviors that comprise a given sexual... more

Introduction. Although studies of specific groups of individuals (e.g., adolescents, "high risk" samples) have examined sexual repertoire, little is known, at the population level, about the sexual behaviors that comprise a given sexual encounter. Aim. To assess the sexual behaviors that men and women report during their most recent sexual event; the age, partner and situational characteristics related to that event; and their association with participants' evaluation of the sexual event. Methods. During March-May 2009, data from a United States probability sample related to the most recent partnered sexual event reported by 3990 adults (ages 18-59) were analyzed. Main Outcome Measures. Measures included sexual behaviors during the most recent partnered sexual event, event characteristics (i.e., event location, alcohol use, marijuana use, and for men, erection medication use), and evaluations of the sexual experience (pleasure, arousal, erection/lubrication difficulty, orgasm). Results. Great diversity exists in the behaviors that occur during a single sexual event by adults, with a total of 41 combinations of sexual behaviors represented across this sample. Orgasm was positively related to the number of behaviors that occurred and age was related to greater difficulty with erections and lubrication. Men whose most recent event was with a relationship partner indicated greater arousal, greater pleasure, fewer problems with erectile function, orgasm, and less pain during the event compared with men whose last event was with a nonrelationship partner. Conclusion. Findings demonstrate that adults ages 18 to 59 engage in a diverse range of behaviors during a sexual event and that greater behavior diversity is related to ease of orgasm for both women and men. Although both men and women experience sexual difficulties related to erectile function and lubrication with age, men's orgasm is facilitated by sex with a relationship partner whereas the likelihood of women's orgasm is related to varied sexual behaviors. Herbenick D, Reece M, Schick V, Sanders SA, Dodge B, and Fortenberry JD. An event-level analysis of the sexual characteristics and composition among adults ages 18 to 59: Results from a national probability sample in the United States.

The present work deals with the numerical solution of the Reynolds equation of lubrication in the speciÿc case where the ÿlm thickness is discontinuous. The present approach is obtained within the framework of a ÿnite volume... more

The present work deals with the numerical solution of the Reynolds equation of lubrication in the speciÿc case where the ÿlm thickness is discontinuous. The present approach is obtained within the framework of a ÿnite volume discretization and enables concentrated inertia e ects to be taken into account, as described by a generalized Bernoulli equation. The classic ÿnite volume formulation is included as a special case when discontinuities are absent. Some numerical examples show that the conservative properties of the ÿnite volume discretization are maintained even when the pressure ÿeld is discontinuous. A typical application shows that the ÿlm discontinuities should always be taken into account in a consistent physical manner in order to eliminate the awkward question of their impact on global results of technological interest. ?

In this paper are presented the power losses and sources of their occurrence in worm gear boxes. These are the losses that occur in the coupling of worm teeth and worm gear, losses in bearings, seals and oil churning power losses in the... more

In this paper are presented the power losses and sources of their occurrence in worm gear boxes. These are the losses that occur in the coupling of worm teeth and worm gear, losses in bearings, seals and oil churning power losses in the transmission. When the operation of worm gearing is characterized by line contact of coupled elements which is accompanied by significant sliding, the highest value have the power losses in the worm and worm gear coupling compared to other losses in gearing. Among other things, in the paper also presents the expressions that are used for calculation of individual power losses and efficiency of the gearing. The size of the losses primarily depends on the type of coupled material and geometry of worm pair, circumferential velocity (input rotational speed), the type and viscosity of lubricating oil, load, worm shape, and temperature and so on. The paper also deals with the influence of different factors on power losses and efficiency. As the efficiency of the worm pair is significantly lower compared to other types of gear pairs, the appropriate combination of geometric parameters and materials of worm and worm gear, lubrication and working conditions can significantly affect its increase.

This paper deals with the analysis of impact of various factors on power loss and efficiency of worm gearing. Factors that significantly affect the power losses are, principally, types of materials of meshed gears and geometry of worm... more

This paper deals with the analysis of impact of various factors on power loss and efficiency of worm gearing. Factors that significantly affect the power losses are, principally, types of materials of meshed gears and geometry of worm pair, type and viscosity of lubricating oils, input rotational speed, worm shape, loading, temperature, etc. Results of experimental tests of worm gearing efficiency are also presented in the paper. Tests were conducted according to planned experiment schedule on specialized device AT200, where single-stage worm gearboxes with transmission ratio i=18 has been used. During the test stage, oils of different viscosities (ISOVG 220, ISOVG 460 and ISOVG 680) have been used and their impact on efficiency was monitored. The values of efficiency level are determined at different input rotational speeds (circumferential velocity) and output torques (loads).

A B S T R A C T Textured surfaces have been shown to provide enhanced tribological performance in a variety of contacts. Numerical analysis and optimisation methods are combined for application-oriented texture optimisation. However, an... more

A B S T R A C T Textured surfaces have been shown to provide enhanced tribological performance in a variety of contacts. Numerical analysis and optimisation methods are combined for application-oriented texture optimisation. However, an analytical approach is advantageous in providing more generic in-depth understanding of the nature of the relationships between texture parameters and objective functions, such as enhanced load carrying capacity and reduced friction. The paper outlines such an approach to obtain a set of global optimum design parameters for partially textured surfaces. The optimised results are expressed in dimensionless form, which enables their use for a variety of applications. The performance of optimised partially textured sliding surfaces is compared with the other conventional bearing geometries in their optimum state.

Lubricating oils are viscous liquids used for lubricating moving part of engines and machines. Lubricating oils are obtained from petroleum a finite product and with dwindling production from world oil reserves, is essential to recognize... more

Lubricating oils are viscous liquids used for lubricating moving part of engines and machines. Lubricating oils are obtained from petroleum a finite product and with dwindling production from world oil reserves, is essential to recognize that all used oils should be collected for controlled disposals. Some products such as transformer oils and hydraulic oils, can be readily collected from large industrial concerns, regenerated to a recognized standard and returned to original source. Oil from automotive sources will include mono and multi-grade crankcase oils from petrol and diesel engines, together with industrial lubricants that have been inadequately segregated may also be included. Lubrication oil is used to provide a film between the moving parts of machines and engines to prevent wear with little or no loss of power.

Properties of Lubricants and Lubrication

The main purpose of this research was to establish the effectiveness of the V844* corrosion inhibitor for seawater on various metallic materials: carbon steel, aluminum and copper alloy at different concentrations via colloid formation.... more

The main purpose of this research was to establish the effectiveness of the V844* corrosion inhibitor for seawater on various metallic materials: carbon steel, aluminum and copper alloy at different concentrations via colloid formation. The changes in both physical and chemical properties of seawater, including pH, total hardness, alkalinity, total dissolved solids (TDS) and conductivity at different concentrations of V844 were assessed, too. The test procedure involves dissolving the V844 corrosion inhibitor (CI) powder provided by Magna International Private Limited in seawater to obtain a stock solution of 4% V844 in seawater, which was further diluted to obtain the remaining concentrations. The analysis of parameters begun when various metal species, polished beforehand, were placed into the solutions. The analysis was observed over a period of 26 days and a total of 9 sets of readings were obtained. From our observation and ear power stations burning fossil-fuels generating acidic rains, the pH can diminish to 6.

The paper presents a review of research data published during last 40-year period in the field of electrical contact lubrication. The paper examines the role of lubrication in corrosion protection as a barrier between contact surfaces and... more

The paper presents a review of research data published during last 40-year period in the field of electrical contact lubrication. The paper examines the role of lubrication in corrosion protection as a barrier between contact surfaces and atmospheric pollutants. For effective long-term corrosion protection, it is important to properly choose and thoroughly qualify a lubrication product for a specific contact material and a specific combination of environmental variables. Another use of lubricants is to protect contacts from mechanical wear and/or friction, and from degradation due to fretting. Conversely, use of inappropriate lubricants may induce a significant risk by producing degradation, collecting participate matter, and developing a high electrical resistance of the contact surfaces. It is very important to carefully choose the lubricants to maintain a stable contact resistance and preserve the physical integrity of the contact surface. This paper also analyzes the effect of chemical composition and consistency (fluids, greases, solid lubricants) on the durability of lubricants in regards to various types of contact material, design and load.

The deformations and stresses during squeeze flows are evaluated for a wider class of materials than previously covered in articles on this subject. These include generalised Newtonian fluids, yield stress fluids, as well as elastic and... more

The deformations and stresses during squeeze flows are evaluated for a wider class of materials than previously covered in articles on this subject. These include generalised Newtonian fluids, yield stress fluids, as well as elastic and viscoelastic materials. Wherever possible, results are given in a compact mathematical form. The effect of different boundary conditions (no slip, perfect slip and partial slip) and how these interact with different types of material behaviour to give a variety of macroscopic responses is also discussed. The significance of this in using squeeze flow as a rheometry method is highlighted and a state-of-the-art view of squeeze flow rheometry is given.

Oral processing of food is a dynamic process involving a range of deformation processes. The mechanical properties and the rheology of food have been widely used to understand and predict in mouth flow properties and to discover... more

Oral processing of food is a dynamic process involving a range of deformation processes. The mechanical properties and the rheology of food have been widely used to understand and predict in mouth flow properties and to discover relationships with sensory perception. However, only limited success has been realised using such approaches to characterise and to interpret food texture. Tribology is emerging as a contributing discipline for understanding oral processing of food as well as texture and mouthfeel, since it encompasses both the fluid's (lubricant's) rheological properties as well as the surface properties of the interacting substrates in relative motion.

Este artículo contiene información real, de un análisis de falla realizado a muestras de cojinetes, un componente de importancia dentro de un motor de combustión interna. Este incluye aclaraciones sobre desgastes, fallas, causas y... more

Este artículo contiene información real, de un análisis de falla realizado a muestras de cojinetes, un componente de importancia dentro de un motor de combustión interna. Este incluye aclaraciones sobre desgastes, fallas, causas y soluciones, de una muestra de cojinetes de un vehículo familiar de uso casual.

The study of textured surface performance is one of the highly researched topics in recent times. This is mainly due to the advantages that such surfaces can potentially provide in practice, in mitigating adverse tribological conditions,... more

The study of textured surface performance is one of the highly researched topics in recent times. This is mainly due to the advantages that such surfaces can potentially provide in practice, in mitigating adverse tribological conditions, such as friction and wear. However, considering the complexities found in practice, a methodological analysis and evaluation procedure is essential in order to gain an understanding of the benefits from utilising such features in a given contact. The current study provides a combined analytical and experimental approach towards an enhanced understanding of the behaviour of textured surfaces relative to their untextured counterparts. The developed analytical models are invaluable in providing an insight into the relationship between the many parameters involved in defining even simple surface texture feature geometry and the expected outcomes in practice, when corroborated with experimental results. The current study reports on such an endeavour. With the studied texture configuration, the results have shown the possibility of reducing friction by as much as 25%.

Tel.: þ33 (0) 1 40 96 65 47; fax: þ33 (0) 1 40 96 62 49. 2 IIR Commission B1 Member. w w w . ii fi i r .o r g a v a i l a b l e a t w w w . s c i e n c e d i r e c t . c o m j o u r n a l h o m e p a g e : w w w . e l s e v i e r . c o m... more

Tel.: þ33 (0) 1 40 96 65 47; fax: þ33 (0) 1 40 96 62 49. 2 IIR Commission B1 Member. w w w . ii fi i r .o r g a v a i l a b l e a t w w w . s c i e n c e d i r e c t . c o m j o u r n a l h o m e p a g e : w w w . e l s e v i e r . c o m / l o c a t e / i j r e f r i g 0140-7007/$ -see front matter ª i n t e r n a t i o n a l j o u r n a l o f r e f r i g e r a t i o n 3 1 ( 2 0 0 8 ) 1 6 5 -1 7 9 Mots clés: Systè me frigorifique Systè me à compression Enquête Lubrification Huile Procé dure Mesure Solubilité Modé lisation r é s u m é

There has been relentless pressure in the second half of the 20th century to develop ever more fuel efficient and compact automobile engines with reduced environmental impact. From the viewpoint of the tribologist this means increasing... more

There has been relentless pressure in the second half of the 20th century to develop ever more fuel efficient and compact automobile engines with reduced environmental impact. From the viewpoint of the tribologist this means increasing specific loads, speeds and temperatures for the major frictional components of the engine, namely, the piston assembly, the valve train and the journal bearings, and lower viscosity engine oils with which to lubricate them. Inevitably, this leads to decreasing oil film thicknesses between the interacting surfaces of these components and a more crucial role for the topography and surface profile of the two surfaces in determining tribological performance. This paper reviews the nature of the surfaces encountered in the piston assembly, valve train and journal bearings of the internal combustion engine and how mathematical models of engine tribology are endeavouring to cope with the extreme complexities the incorporation of surface topography potentially brings. Key areas for future research and the implications for design are highlighted. q

In this study, a review of the available literature on lubrication techniques during machining processes was conducted. Factors such as workpiece material, tool material and machining conditions were observed to be vital to the... more

In this study, a review of the available literature on lubrication techniques during machining processes was conducted. Factors such as workpiece material, tool material and machining conditions were observed to be vital to the performance of any of the techniques. The performance and drawback of each technique were highlighted based on the machining conditions. It concludes by making a case for minimum quantity lubrication (MQL) method using vegetable oil-based lubricant in different machining processes, as a way of addressing the environmental health issues and cost associated with the application of lubricant in machining processes.

“Esta es la Tercera Edición de la Revista Lubricación y Mantenimiento Industrial, muchas gracias a todos por hacer posible esta publicación.” Durante este año 2017, hemos participado con un grupo multidisciplinario en un proyecto que... more

“Esta es la Tercera Edición de la Revista Lubricación y Mantenimiento Industrial, muchas gracias a todos por hacer posible esta publicación.”
Durante este año 2017, hemos participado con un grupo multidisciplinario en un proyecto que lidera el Organismo Supervisor de la Inversión en Energía y Minería OSINERGMIN – PERÚ y ABS Group del Perú. El objetivo del proyecto es la implementación del Sistema de Gestión de Seguridad de los Procesos en la Industria de la Refinación y Procesamiento de Hidrocarburos.
Y gracias a la experiencia que se ha logrado, para esta edición, vamos aportar de una manera breve, práctica y sencilla las herramientas necesarias para implementar un Sistema de Gestión de Seguridad de Procesos (Process Safety Management).

Lift is a simple device use to raise the object from ground level to a certain height to perform a specific work with aiming of possible maximum load and minimum efforts. Lifts are generally operated either hydraulic, pneumatic or... more

Lift is a simple device use to raise the object from ground level to a certain height to perform a specific work with aiming of possible maximum load and minimum efforts. Lifts are generally operated either hydraulic, pneumatic or mechanical type. In many vehicle manufacturing industries, there are using lifting mechanism for loading and unloading operations which have to invest a huge capital for installing a exsisting bulkey and large platform which generally based on hydraulic means. This type of machine uses while export and import business. The main purpose of our study is to design and development of loading and unloading platform for two wheelers. Material selection plays important role in designing a machine and also influence on several factor such as strength, reliability, durability and resistance which leads to increase the life of lift. The aim of the project is to design and development of wire rope operated platform which lifts maximum 877.5 kg load including factor of safety with minimum time and labour for per cycle operation. Platform movement is achieved safely by using wire rope with the help of gear motor and drum assembly mechanism is of 2.8 m from the ground level. The design is performed by considering a mechanical lift as a portable, suitable for all type of load application and without any hydraulic or pneumatic means. The design is developed keeping in mind that consideration of all safety parameters. Lubrication required in few moving parts only. The aim of this paper is design, analysis and fabrication of a mechanical lift model which operate efficiently, consistently, sholud be easy to handle, multifunctional, cost effective, compact in size. Drafting and drawing of loading and unloading mechanical lift carried out in AUTOCAD with suitable modeling. The analysis of mechanical lift includes total deformation load, reaction forces, buckling and bending failures, equivalent stresses were done in ANSYS Software. Finally this analysis of strength, toughness, elasticity and temperature distribution is carried out in order to check the coherance of the design value.

The overall objective of this study was to provide 'semi-quantitative' or 'rigorous' definitions of the fluidity, lubricity and compactibility requirements of formulation for representative dosator and dosing disc capsule filling... more

The overall objective of this study was to provide 'semi-quantitative' or 'rigorous' definitions of the fluidity, lubricity and compactibility requirements of formulation for representative dosator and dosing disc capsule filling machines. To that end, model formulations were developed for those properties using Carr's compressibility index, ejection force, and plug breaking force at a specified compression force to gauge fluidity, lubricity, and compactibility, respectively. These formulations were each encapsulated on an Hofliger-Karg GKF-400 dosing disc machine and a Zanasi LZ-64 dosator machine. Each machine was instrumented to measure plug compression and ejection forces. The encapsulation process was evaluated for %CV of fill-weight, ejection force, plug breaking force and the dissolution of marker drugs incorporated in the formulations. The f 2 metric was used to compare dissolution profiles. The results suggest: (1) formulations should meet different flow criteria for successful encapsulation on the two machines, (2) a relatively lower level of lubricant may be sufficient for the dosing disc machine, (3) a higher degree of formulation compactibility is needed for the dosator machine, and (4) transferring formulations between these machine types (same class, different subclass per FDA's SUPAC-IR/MR Manufacturing Equipment Addendum) could be challenging. In certain cases dissolution profiles for the same formulation filled on the two machines with equivalent compression force were different based on f 2 < 50. Overall, the results of this study suggest a range of formulation characteristics appropriate for transferring formulations between these two types of machines.

A systematic approach is required in order to determine the frictional characteristics of a contacting pair in the presence of a tribofilm. Despite the clear benefits in functionality and in reducing wear, the generation of ZDDP-based... more

A systematic approach is required in order to determine the frictional characteristics of a contacting pair in the presence of a tribofilm. Despite the clear benefits in functionality and in reducing wear, the generation of ZDDP-based tribofilms often lead to increased frictional losses. Such an increase is also observed in the tribometric tests reported here, as well as in open literature. This paper investigates the underlying mechanics for the rise in friction using an integrated methodology, based upon Atomic Force Microscopy (AFM) and X-ray Photoelectron Spectroscopy (XPS). The use of an analytical contact mechanics model demonstrates that the pressure coefficient of boundary shear strength, measured using lateral force microscopy, provides an explanation for the observed increase in measured friction at micro-scale.

The objective of this study was to characterize physical properties including thickness, colour, water vapour sorption kinetics and isotherms, water vapour permeability, tensile strength, elongation at break, and microstructure of... more

The objective of this study was to characterize physical properties including thickness, colour, water vapour sorption kinetics and isotherms, water vapour permeability, tensile strength, elongation at break, and microstructure of composite films prepared by casting sodium alginate and low methoxy pectin at proportions of: 100-0%, 75-25%, 50-50%, 25-75%, and 0-100%. Combination of both polysaccharides gave continuous, homogenous and transparent films. All of analyzed films reached their state of equilibrium within the 24 h of adsorption time. Water sorption isotherms for all films had a sigmoidal shape and were not influenced by the film composition. Sorption kinetics and isotherms indicated hydrophilic character of investigated films. Statistically significant (p < 0.001) correlations were found between colour, water vapour permeability, tensile strength, elongation at break, and chemical composition (alginate and pectin) of composite films. A different internal arrangement was observed as a function of film composition.

The aim of the present research was to investigate influence of surface preparation on roughness parameters and correlation between roughness parameters and friction and wear. First the correlation between different surface preparation... more

The aim of the present research was to investigate influence of surface preparation on roughness parameters and correlation between roughness parameters and friction and wear. First the correlation between different surface preparation techniques and roughness parameters was investigated. For this purpose 100Cr6 steel plate samples were prepared in terms of different average surface roughness, using different grades of grinding, polishing, turning and milling. Different surface preparation techniques resulted in different R a values from 0.02 to 7 m. After this, correlation between surface roughness parameters and friction and wear was investigated. For this reason dry and lubricated pin-on-disc tests, using different contact conditions, were carried out, where Al 2 O 3 ball was used as counter-body. It was observed that parameters R ku , R sk , R pk and R vk tend to have influence on coefficient of friction.

The lubricant-surface system is complex in nature and can significantly affect the frictional performance of high-performance transmission systems. The complexity stems from the coupled mechanical and chemical phenomena that occur at the... more

The lubricant-surface system is complex in nature and can significantly affect the frictional performance of high-performance transmission systems. The complexity stems from the coupled mechanical and chemical phenomena that occur at the inter-facial tooth conjunctions. A combined analytical and precision experimental approach is presented to analyse the salient parameters of the lubricant-surface system. A multiscale procedure comprising topographical measurement, pin-on-disc tribometry, atomic force microscopy in lateral force mode, X-ray photo-electron spectroscopy and continuum contact mechanics analysis under mixed non-Newtonian thermo-elastohydrodynamics is used to describe the formation of a tribo-film, as well as wear and frictional characteristics of the lubricant-surface system. The contribution of chemisorbed and physisorbed bonded tribo-film on the boundary coefficient of friction is ascertained at different physical scales. Therefore, the paper presents a novel multiscale analysis, promoting improved understanding of the complex interactions between mechanisms of friction, wear and surface chemistry. Keywords Gear · Tribo · Film · Additive · ZDDP · AFM · Atomic force microscopy · Wear · Friction

The main objective was to study the potency of MQL palm oil (MQLPO) as a lubricant in the high speed drilling of Ti-6Al-4V. For the comparison, MQL synthetic ester (MQLSE), air blow and flood conditions were selected. Uniform flank wear,... more

The main objective was to study the potency of MQL palm oil (MQLPO) as a lubricant in the high speed drilling of Ti-6Al-4V. For the comparison, MQL synthetic ester (MQLSE), air blow and flood conditions were selected. Uniform flank wear, micro-chipping, thermal cracking and flaking were the dominant tool failure modes. It was found that MQLSE and MQLPO gave comparable performance with the flood conditions. In addition, MQLPO outperformed MQLSE on the cutting forces, temperature, power and specific cutting energy. This shows that palm oil can be used as a viable alternative to synthetic ester for MQL lubricant.

This study presents calculations on the global fuel energy consumption used to overcome friction in passenger cars in terms of friction in the engine, transmission, tires, and brakes. Friction in tribocontacts was estimated according to... more

This study presents calculations on the global fuel energy consumption used to overcome friction in passenger cars in terms of friction in the engine, transmission, tires, and brakes. Friction in tribocontacts was estimated according to prevailing contact mechanisms such as elastohydrodynamic, hydrodynamic, mixed, and boundary lubrication. Coefficients of friction in the tribocontacts were estimated based on available information in the literature on the average passenger car in use today, a car with today's advanced commercial tribological technology, a car with today's best advanced technology based upon recent research and development, and a car with the best technology forecasted in the next 10 years. The following conclusions were reached:

The aim of the present investigation was to examine the possibility of reducing lubrication and replacing expensive tungsten carbide material in blanking/piercing through introduction of hard tool coatings. Results show that hard PVD... more

The aim of the present investigation was to examine the possibility of reducing lubrication and replacing expensive tungsten carbide material in blanking/piercing through introduction of hard tool coatings. Results show that hard PVD coatings can be successfully used in blanking/piercing applications, even on softer tool steels, thus leading to reduced friction and wear as well as to lower costs of the tool. However, preparation of the substrate material and good coating to substrate adhesion are crucial. On the other hand, even with the use of low friction coating (DLC) stamping force exceeds critical value under dry friction conditions and leads to tool failure. Therefore, at present oxidation and temperature resistant hard coatings can give improved wear resistance of stamping tools, but elimination of lubricants in blanking and piercing processes is still not feasible.