Showing papers in "Industrial Lubrication and Tribology in 2005"
TL;DR: In this paper, a mixture of nano-sized molybdenum disulfide (MoS2) and commercial common MoS2 particles (approximately 1.5 μm in diameter) were dispersed in liquid paraffin with different concentrations and ratios by means of ultrasonic in order to study their lubrication capacity, friction reduction and wear resistance.
Abstract: Purpose – To provide a suitable useful mixing ration of nano‐sized molybdenum disulfide and commercial common molybdenum sulfide (MoS2) particles (approximately 1.5 μm in diameter) in liquid paraffin, which can lead to a better tribological performance.Design/methodology/approach – The MoS2 nanoparticles and commercial common MoS2 particles (approximately 1.5 μm in diameter) were dispersed in liquid paraffin with different concentrations and ratios by means of ultrasonic in order to study their lubrication capacity, friction reduction and wear resistance. The tribological experiments were carried out by MQ‐800 four‐ball tribometer, in which extreme pressure, wear scan diameter and friction coefficient were measured. It was analyzed that the chemical status of elements on the rubbed surface by X‐ray photoelectron spectroscopy (XPS), and it was observed that the surface topography of wear scan by scanning electron microscope (SEM).Findings – The results showed that the loading capacity of liquid paraffin wi...
60 citations
TL;DR: In this article, an online condition monitoring device for engine oil was developed based on the previous works in this line and some testing of used oils in the laboratory, the correlation of change in colour with other properties were identified.
Abstract: Purpose – Engine oil degrades in quality during its use and after certain period of time the oil needs to be changed depending upon its condition. The purpose of this paper is to design and develop an online condition monitoring device for engine oil.Design/methodology/approach – Based on the previous works in this line and some testing of used oils in the laboratory, the correlation of change in colour with other properties were identified. An optical colour sensor was then designed and developed which can transform the darkness of oil colour into electrical resistance. A series of tests were undertaken to calibrate the system for its correctness.Findings – This type of sensor provides the information about the condition of the oil and also can inform about the probable time for drain‐off of the oil.Practical implications – Engine oil changes are normally done by schedules which are highly conservative and cost the user as the oil is changed when it could be still used for some time. Use of an online sen...
48 citations
TL;DR: In this paper, the authors study and estimate changes of various properties upon use of engine oil by different methods, including viscosity measurement, pH measurement, Fourier transform infra-red spectroscopic analysis and UV-Visible (Ultraviolet and visible rays) spectroscopy analysis.
Abstract: Purpose – To study and estimate changes of various properties upon use of engine oil by different methods.Design/methodology/approach – By viscosity measurement, pH measurement, Fourier transform infra‐red spectroscopic analysis and UV‐Visible (Ultraviolet and visible rays) spectroscopic analysis.Findings – Some specific changes in additives of the oil upon use could be traced.Practical implications – Correct choice for additives for a particular use may enhance the oil life and also protect the engine from damage.Originality/value – The findings may be important to the lube oil producers and the users.
32 citations
TL;DR: In this paper, the brake linings were subjected to friction and wear tests under different loads, and changes in the hardness and microstructures were examined, and a direct proportional relationship was not found between hardness and wear resistance due to the complexity of composite structure.
Abstract: Purpose – The aim of the research is to investigate the ceramic brake lining on the brake performance.Design/methodology/approach – The brake lining which has new formulation has been produced by using various additive materials. Various techniques have been used in the production of brake lining. These ceramic linings were subjected to friction and wear tests under different loads, and changes in the hardness and microstructures were examined.Findings – As a result of this study, the following findings are reported. A direct proportional was not found between hardness and wear resistance due to the complexity of composite structure. Kevlar fibers were homogeneously distributed in the matrix and therefore, very few microvoids were observed in the structure. Similarly, stone wool was well spread out the braking pad and hence decreased the microvoids' occurrence. Heat treatment supplied more homogeneous structure and hence, microstructural variations were minimised during the brake action. On the other hand...
29 citations
27 citations
TL;DR: In this paper, the results of research carried out on esters of carbonic, adipic, and sebacic acids with respect to their use as components of fully synthetic lubricating oil produced from a polyalphaolefin base were presented.
Abstract: Purpose – The paper presents the results of research carried out on esters of carbonic, adipic, and sebacic acids with respect to their use as components of fully synthetic lubricating oil produced from a polyalphaolefin base. Straight dicarboxylic acid esters were synthesized in a transesterification reaction of dimethyl carbonate, dimethyl adipate, and dimethyl sebacate with 2‐ethylhexanol and 3,5,5‐trimethylhexanol.Design/methodology/approach – Oligomeric esters of adipic acid and sebacic acid were synthesized using neopentyl glycol, appropriate dimethyl adipate or dimethyl sebacate and 2‐ethylhexanol as the starting material. The basic physicochemical properties of esters were determined and their compatibility with synthetic oils were defined. They were also evaluated with respect to resistance under the influence of thermo‐oxidative factors, evaporation and susceptibility to hydrolytic decomposition. The selected esters were complemented with commercial additives to make up a fully synthetic lubrica...
19 citations
TL;DR: In this article, three ceramics were used for this purpose and these coated parts were subjected to wear tests under a stable load and the results showed that Al2O3 and ZrO2 were the best coating material with low wearing rate.
Abstract: Purpose – The aim of the research is to investigate the influence of ceramic coating on the wear performance of machine parts.Design/methodology/approach – Ductile cast iron parts were coated using ceramics. Three ceramics were used for this purpose. These coated parts were subjected to wear tests under a stable load. A pin‐on‐disc wear test apparatus was used.Findings – As a result of this study, the following findings are reported: According to ASTM G 99‐90 pin‐on‐disc experiments, Cr2O3 was found to be best coating material with low wearing rate. Within row, Al2O3 and ZrO2 can be given. According to the previous work, motor parts for example piston ring, cylinder liner and engine valve can be coated with ceramic. In this study, it is observed that the figure of merit is increased in this study. Only wearing data is given in this research. The other results are also supporter of the results taken from the wearing experiments. As a result, due to the decrease in heat loss and coaling stability of part ca...
17 citations
TL;DR: In this paper, the role of chemical ingredients and emulsifier in lubrication and tribological characteristics of rolling oil was investigated with the help of an ultra thin film interferometry EHD test rig, an advanced experimental rolling mill and a Coulter LS 230 instrument.
Abstract: Purpose – Oil‐in‐water (O/W) emulsion has been used in industrial rolling mills for many decades, but its lubrication mechanism is still not adequately understood. There is a need to understand the role of chemical ingredients and emulsifier in lubrication and tribological characteristics of rolling oil. With this purpose, the authors selected three commercially available O/W emulsions of different generations and of known industrial performance. The aim is to understand the lubrication mechanism of these rolling oils and to correlate the laboratory findings with that of industrial rolling mills.Design/methodology/approach – The lubrication mechanism has been studied with the help of an ultra thin film interferometry EHD test rig, an advanced experimental rolling mill and a Coulter LS 230 instrument. Film thickness, rolling parameters and droplet size were measured. The coefficient of friction was computed with the help of the measured values of rolling parameters. Emulsion stability and saponification va...
17 citations
TL;DR: In this article, a green cutting with water vapor as coolant and lubricant is studied and compared to dry cutting, compressed air, oil water emulsion, and dry cutting.
Abstract: Purpose – Nowadays, green cutting has become the focus because of its ecological problem and the necessary environment protection, so that the research on experimentation of green cutting with water vapor as coolant and lubricant is studied because water vapor has many benefits of cheapness, no pollution, no harm and no recycling and handling.Design/methodology/approach – The vapor generator and the vapor feed system are manufactured, the distribution of temperature and velocity of vapor jet flow are simulated by MATLAB program, and under the conditions of compress air, oil water emulsion, water vapor as coolant and lubricant and dry cutting, respectively, the turning experimentation of comparison which the tool is YT15, and the working material is steel 45.Findings – Water vapor, as coolant and lubricant, the cutting force is reduced, respectively about 30‐40, 20‐30 and 10‐15 percent by comparing to dry cutting, compressed air and oil water emulsion. The cutting temperature is, respectively about 30, 40 ...
16 citations
TL;DR: In this article, the authors derived a dynamic Reynolds-type equation governing the film pressure to account for the couple stress effects resulting from the non-Newtonian behavior of complex fluids.
Abstract: Purpose – The purpose of the present study is to provide the dynamic characteristics of long journal bearings lubricated with couple stress fluids.Design/methodology/approach – Based upon the micro‐continuum theory generated by Stokes, the dynamic Reynolds‐type equation governing the film pressure is derived to account for the couple stress effects resulting from the non‐Newtonian behavior of complex fluids. By applying the linear stability theory to the non‐linear equations of motion the journal rotor, the equilibrium positions and dynamic characteristics of the system are evaluated.Findings – As compared to the classical Newtonian model, the effects of couple stresses signify enhanced stiffness and damping coefficients (including KXX, KXY , BXX and BXY) at moderate values of the steady eccentricity ratio. Totally, as the rotor center operates at an eccentricity ratio about es≤0.71, long bearings lubricated with couple stress fluids under small disturbance results in a higher stability threshold speed th...
15 citations
TL;DR: In this article, a multi-layer carbon-chromium composite coating was applied to the gears of a gearbox to provide tribological protection against scuffing failures, wear and the influence on gear power losses.
Abstract: Purpose – Provide tribological information about the applicability of multi‐layer carbon‐chromium composite coatings to gears. Discuss the protection provided against scuffing failures, wear and the influence on gear power losses.Design/methodology/approach – Several screening tests, such as Rockwell indentations, ball cratering, pin‐on‐disc and reciprocating wear tests, were performed in order to evaluate the adhesion to the substrate and the tribological performance of the carbon/chromium composite coating. Afterwards, twin‐disc tests were performed at high contact pressure and high slide‐to‐roll ratios to confirm the good adhesive and tribological properties of the coating under operating conditions similar to those found in gears. Gear tests were performed in the FZG machine in order to evaluate the anti‐scuffing performance of the carbon/chromium coating using additive free gear oils. Finally, the carbon/chromium composite coating was also applied to the gearing in a gearbox and its influence on the ...
TL;DR: In this article, the authors developed a thermo-mechanical model to predict the tribological behavior of the composite PEEK CF30/steel pair, in dry sliding, related to friction and wear with the pv factor, the temperature and the sliding distance.
Abstract: Purpose – PEEK is an abbreviation for polyetheretherketone, a high performance engineering semicrystalline thermoplastic This material can operate at higher temperatures and has excellent friction and wear properties, which are optimised in the specially formulated tribological grade PEEK‐CF30 The purpose of this work was to develop a thermo‐mechanical model to predict the tribological behaviour of the composite PEEK‐CF30/steel pair, in dry sliding, related to friction and wear with the pv factor, the temperature and the sliding distance, using multiple regression analysis (MRA)Design/methodology/approach – This paper presents a new thermo‐mechanical model to predict the tribological behaviour of the composite PEEK‐CF30/steel pair, in dry sliding, using MRA A plan of experiments was performed on a pin‐on‐disc machine PLINT TE67HT®Findings – The objective was to establish a thermo‐mechanical model to predict the PEEK‐CF30 behaviour related to friction and wear with the pv factor (product of apparent p
TL;DR: In this article, the combined effects of permeability and couplestresses on the performance characteristics of a secant-shaped porous slider bearing lubricated with Stokes Couplestress fluid was studied, and the bearing characteristics were computed for various values of the couple stress parameter, slip parameter and the permeability parameters.
Abstract: Purpose – To study the combined effects of permeability and couplestresses on the performance characteristics of a secant‐shaped porous slider bearing lubricated with Stokes couplestress fluid.Design/methodology/approach – The modified Reynolds type equation governing the fluid film pressure is derived on the basis of Stokes microcontinuum theory of couplestress fluids by using Beavers‐Joshep slip boundary conditions at the fluid‐porous interface. The modified Reynolds equation is solved analytically and closed form expressions are obtained for the fluid film pressure, load carrying capacity, frictional force and centre of pressure.Findings – The bearing characteristics are computed for various values of the couple stress parameter, slip parameter and the permeability parameters. It is found that, the effect of couple stress is to increase the load carrying capacity and to decrease the coefficient of friction as compared to the Newtonian case. However, the effect of permeability parameter is to decrease t...
TL;DR: A semi-analytical and semi-numerical solution for the squeeze film lubrication of long porous partial journal bearings lubricated with couple stress fluid is presented in this paper, where the modified Reynolds equation governing the fluid film pressure is derived.
Abstract: Purpose – This paper aims to advance the squeeze film characteristics of long partial journal bearings with couple stress fluid studied by Lin to include the effect of permeability on the squeeze film lubrication of long partial porous journal bearings with couple stress fluids.Design/methodology/approach – A semi‐analytical and semi‐numerical solution for the squeeze film lubrication of long porous partial journal bearings lubricated with couple stress fluid is presented in the paper. The modified Reynolds equation governing the fluid film pressure is derived. The modified Reynolds equation is solved analytically and closed form expressions for the squeeze film pressure and load carrying capacity are presented. The first‐order non‐linear equation for the time‐height relation is solved numerically with the given initial condition. The effect of couple stresses and permeability on the squeeze film characteristics are discussed.Findings – It is found that the effect of couple stresses is to increase the loa...
TL;DR: In this article, the load carrying capacity of the journal bearings with steel shafts with varying surface texture in varying revolutions using experimental and neural network (NN) approach was investigated, and the proposed neural predictor would be used as a predictor for possible experimental applications on modelling bearing system.
Abstract: Purpose – This paper investigates the load carrying capacity of the journal bearings with steel shafts with varying surface texture in varying revolutions using experimental and neural network (NN) approach.Design/methodology/approach – In this study, we used a shaft with smooth surface with the same material properties compare their load carrying capacities of the shafts with three different pitches and two different profiles. The experimental data, such as pressure and oil temperature, are employed as training and testing data for NN. Quick Prop algorithm is used to update the weight of the network during the training.Findings – The designated NN has superior performance for modelling of the system. Therefore, the proposed neural predictor would be used as a predictor for possible experimental applications on modelling bearing system.Research limitations/implications – Mobil 0W‐40 lubricant was used and kept at temperature of 18°C. The surface of the shafts has been in two types: smooth, that is without...
TL;DR: In this paper, the authors presented new designs of magnetic fluid exclusion seals for rolling bearings, such as compact magnetic fluid seals, two-stages sealed two-stage system, and radial lip sealed system.
Abstract: Purpose – To present some new designs of magnetic fluid exclusion seals for rolling bearings and possibility to use them in modern industrial sealing applications.Design/methodology/approach – In the paper is given principle of magnetic fluid sealing technology and are presented new designs of magnetic fluid exclusion seals for rolling bearings, such as compact magnetic fluid seals, two‐stages seals being combination of magnetic fluid seal and labyrinth seal or radial lip seal, magnetic fluid seals with “floating” magnetic system. This paper also shows examples of their application in various rotating process equipment.Findings – Provides information about new designs of bearing seals and gives the main advantages of these seals over other types, such as total tightness, low viscous drag, maintenance‐free service and high reliability.Originality/value – This paper offers some new designs of high‐performance magnetic fluid exclusion seals for rolling bearings and points their practical applications.
TL;DR: In this paper, a new "wet" coating technique is proposed to modify steel surfaces of all kinds of bearing. But the results of an official bearing test are not available.
Abstract: Purpose – To prevent damages of machinery elements and enhancing life lubrication by using new surface engineering techniques.Design/methodology/approach – A new “wet” coating technique offers an easy and promising route to modify steel surfaces. The design of surface coatings and the results of an official bearing test are presented.Findings – Based on common bearing tests (e.g. DIN 51819), wear behaviour and tribological properties of modified surfaces are verified.Research limitations/implications – Our actual research proves an enhanced tribological behaviour in the case of improving surface properties. In contrast, to the common vapour deposition techniques the “wet” coating method seems to offer an alternative route to get surfaces with enhanced tribological properties.Practical implications – The technique of “wet” coating offers an easy route to modify steel surfaces of all kinds of bearings.Originality/value – Pre‐polymer coating provides a promising future technique for surface engineering.
TL;DR: In this paper, two tetrazole derivatives, n−hexadecanyl (1H−tetrazol−1−yl) acetate (HTA) and 1−phenyl−5−(octylthio) tetrazole (PCT), were synthesized and added to hydrogenised oil with different concentrations.
Abstract: Purpose – To study some tribochemical properties of tetrazole derivatives, n‐hexadecanyl (1H‐tetrazol‐1‐yl) acetate (HTA) and 1‐phenyl‐5‐(octylthio)‐tetrazole (PCT) as lubricating oil additives in hydrogenised oil, and estimate the action mechanism.Design/methodology/approach – The two tetrazole compounds were synthesized, and added them in hydrogenised oil with different concentrations. Their anti‐wear properties were evaluated with a four‐ball machine, the wear scar was analyzed with a X‐ray photoelectron spectroscopy (XPS).Findings – The novel compounds possess good anti‐wear, friction reduction properties and good load‐carrying capacity. According to the XPS results, the novel compounds were migrated onto the surface of the steel balls and adsorbed on the surface. The two additive compounds, themselves, and their decomposers contributed to the corresponding tribological performances. With S element contained in the compound PCT, the influence on the load‐carrying capacity of the base oil was enhanced....
TL;DR: In this paper, the effects of slip velocity and a magnetic fluid lubricant characterised by a material parameter on a parallel plate porous slider bearing were theoretically analyzed and the analysis might be useful in designing better slider bearings useful in machines like gas turbines.
Abstract: Purpose – Our purpose was to theoretically analyse the effects of slip velocity and a magnetic fluid lubricant characterised by a material parameter on a parallel plate porous slider bearing. Various special cases were also discussed.Design/methodology/approach – The analysis might be useful in designing better slider bearings useful in machines like gas turbines.Findings – Computed values displayed in tabular form show that frictional force on the slider and the coefficient of friction decreased, the load capacity and the position of the centre of pressure unaltered when the slip parameter was increased. On the other hand, increase in the material parameter caused decrease in the frictional force and the coefficient of friction and, shift of the position of the centre of pressure towards the bearing inlet with no change in the load capacity of the bearing.Originality/value – The parallel plate slider bearing cannot support a load with a conventional lubricant. However, it can support a load with a magnet...
TL;DR: In this paper, wear behavior of boronized GGG-80 ductile cast iron was studied against WC-Co ball for determining the effect of Boronizing time and temperature.
Abstract: Purpose – Wear behavior of boronized GGG‐80 ductile cast iron were studied against WC‐Co ball for determining the effect of boronizing time and temperature.Design/methodology/approach – Ball on disk arrangement was used for determination of tribological properties of boronized ductile cast iron depending on process time and temperature. Boronizing treatment was performed on GGG‐80 ductile cast iron using salt bath immersion boronizing technique at 850 and 950°C for 2‐8 h. Friction and wear tests were carried out at dry test conditions under 2, 5 and 10 N loads with 2.5 m/min sliding speed.Findings – The result showed that the friction coefficient values ranged from 0.12 to 0.2 depending on the process parameters. The higher the treatment temperature and the longer the treatment time, the thicker the boride layer, the more the FeB phase and the higher the specific wear rate became. The specific wear rate of boronized ductile cast irons depending on process time, temperature and applied load against WC‐Co b...
TL;DR: In this paper, the authors defined the lubricating durability D based on definition of three characteristic points Pd, PS, Pi and three key time lengths Td, Ts, Ti.
Abstract: Purpose – Improved fuel economy, lower emission and longer durability are the major developing trends of engine oils. Aims to describe further research on the friction coefficient of engine oils.Design/methodology/approach – The lubricating durability D was defined based on definition of three characteristic points Pd, PS, Pi and three key time lengths Td, Ts, Ti. Two kinds of engine oils, respectively, belonging to GF‐2 and GF‐3 categories, were selected as samples to compare their lubricating durability.Findings – Test results indicate the GF‐3 oil has much better lubricating durability than GF‐2 oil. With investigation of the topography and chemical composition changes of wear tracks along with the tribotests' time extending, the meanings of three characteristic points were discussed. Analysis indicates much better tribofilm, formed by the synergistic effect of Ca‐containing detergent with MoDTC/ZDTP in GF‐3 oil, is the major factor resulting in GF‐3 oil's longer lubricating durability.Originality/valu...
TL;DR: In this article, series ashless P-containing EA and AW additives with different chemical structures were designed and selected, their EP and AW performances, high-temperature oxidation, hydrolytic stability compared with the traditional zinc dialkyldithiophosphate (ZDDP) additive were investigated according to relative testing standards, and their applied performances were investigated using the traditional ZDDP additive.
Abstract: Purpose – In order to formulate ashless GL‐5 gear oils and high‐pressure antiwear hydraulic oils, the performances of extreme‐pressure (EP) and antiwear (AW), and the thermal and hydrolytic stability of series ashless P‐containing additives with different chemical structures are investigated by four‐ball EP test, high‐temperature oxidation test and hydrolytic stability test.Design/methodology/approach – Series ashless P‐containing EP and AW additives with different chemical structures were designed and selected, their EP and AW performances, high‐temperature oxidation, hydrolytic stability compared with the traditional zinc dialkyldithiophosphate (ZDDP) additive were investigated according to relative testing standards, and their applied performances compared with the traditional ZDDP additive were investigated using the CRC L‐37 gear oil rear axle test, Deniso T‐5D Vane Pump test and Deniso P‐46 Piston Pump test.Findings – The results indicate that two ashless neutral thiophosphate esters exhibit excelle...
TL;DR: In this paper, a Grubin-type EHL inlet zone analysis is carried out for the isothermal EHL of line contacts in special operating conditions, i.e. extremely heavy loads or extremely low rolling speeds based on the Newtonian fluid model.
Abstract: Purpose – To make a derivation of the load‐carrying capacity of elastohydrodynamic lubrication for special operating conditions, i.e. extremely heavy loads or extremely low rolling speeds based on the Newtonian fluid model by taking the Grubin‐type EHL inlet zone analysis, justify the load‐carrying capacity of elastohydrodynamic lubrication film in these operating conditions, and propose future trends of the research in EHL and mixed EHL based on the obtained results in the present paper.Design/methodology/approach – A Grubin‐type EHL inlet zone analysis is carried out for the isothermal EHL of line contacts in special operating conditions, i.e. extremely heavy loads or extremely low rolling speeds based on the Newtonian fluid model. Comparison is made between the central EHL film thickness in line contacts, respectively, predicted by conventional EHL theories and accurately predicted from the present analysis for these operating conditions. An interpretation is made for the EHL film thickness in these op...
TL;DR: In this paper, the authors examined the mechanical properties of PVD coated Ti•6Al•4V alloy through three-point bending tests and found that the coating failure occurs due to shearing effect on the tensile surface.
Abstract: Purpose – To examine the mechanical properties of TiN PVD coated Ti‐6Al‐4V alloy through three‐point bending tests.Design/methodology/approach – Ti‐6Al‐4V alloy is cut in size and polished and cleaned chemically before TiN PVD coating process. INSTRON three‐point bending equipment is used to conduct the bending tests for TiN coated and uncoated workpieces. During the tests, the load and displacement characteristics were recorded. The tests were terminated when the coating failed. Micrographs of surface and crack sites were obtained by SEM.Findings – Coating failure occurs due to shearing effect on the tensile surface. The spalling and buckling of the coating on the compressive surface are observed. The compressive stress generated on the top surface (where the indent is in contact) did not cause adhesive failure of the coating. Moreover, cohesive cracks occur on the tensile surface of the coating. The crack ledge under the action of shear stress appears on the tensile surface of TiN coating and multi crac...
TL;DR: In this paper, the stability characteristics of a hybrid oil film bearing with dual-row recesses and orifice compensated restrictors were analyzed for a Jeffcott rotor-hybrid bearing system and the results indicated that the stability of the hybrid bearing system could be improved by using shallow, dual-recessed hybrid bearings with orifice compensation.
Abstract: Purpose – The present paper proposes a theoretical analysis of the stability characteristics of a Jeffcott rotor‐hybrid bearing system. It is intended that on the basis of the numerical results drawn from this study, appropriate recess depth, land size, orifice location and speed parameter for stable operation can be determined for use in the bearing design process.Design/methodology/approach – A Jeffcott rotor supported by hybrid oil film bearings with dual‐row recesses and orifice‐ compensated restrictors is studied. In order to facilitate the calculation of film dynamics, using the perturbation method, the Reynolds equation was linearized and subsequently solved using finite difference techniques, whilst the stability maps were determined by the Routh‐Hurwitz method.Findings – The data reported here suggest that the stability characteristics of the Jeffcott rotor‐bearing system could be improved by the use of shallow, dual‐recessed hybrid bearings with orifice compensation. In addition to greater eccen...
TL;DR: In this paper, a study of an optimisation model based on genetic algorithms (GAs) is presented, where the exchange of structured information based on natural selection principles and "Survival-of-the-fittest" allows the combination of solutions in a sequence of generations leading to the best solution.
Abstract: Purpose – Surface roughness is an important parameter in manufacturing engineering with significant influence on the performance of mechanical parts. Failures, sometimes catastrophic failures, leading to high costs, have been imputed to a component's surface roughness. Owing to the need for improvement of machining parameters in order to obtain a prescribed surface roughness, new developments have been recently investigated. This work aims to report on a study of an optimisation model based on genetic algorithms (GAs).Design/methodology/approach – The developed algorithm considers a machining parameter data population obtained from experimental tests. The exchange of structured information based on natural selection principles and “survival‐of‐the‐fittest” allows the combination of solutions in a sequence of generations leading to the best solution.Findings – Over standard experimental design methodologies the proposed GA approach shows advantages in finding the optimal conditions under the imposed constr...
TL;DR: In this article, a new mode of mixed elastohydrodynamic lubrication (mixed EHL) was proposed, which is more realistic and of more application values to a practical elasthydrodynamic contact on gears, cams and roller bearings than the previous and current existing mixed EHL models.
Abstract: Purpose – To form and develop a new mode of mixed elastohydrodynamic lubrication (mixed EHL) which is more realistic and of more application values to a practical elastohydrodynamic contact on gears, cams and roller bearings than the previous and current existing mixed EHL models.Design/methodology/approach – The representative theoretical and experimental studies on elastohydrodynamic lubrication (EHL) and mixed EHL carried out in the previous and recent time, including those of the author, are reviewed. The obtained results on EHL and mixed EHL in those studies and the viewpoints on the mode of mixed EHL based on those results developed in those studies are compared and evaluated. Strong proves are formed on the new mode of mixed EHL proposed in the present paper based on these comparisons and evaluations.Findings – Strong viewpoints are formed on the mode of the occurrence of dry contact in EHL in a practical concentrated contact. A new mode of mixed EHL is proposed by incorporating this mode of the oc...
TL;DR: Worn parts welded using the gas metal arc welding process showed better wear resistance, and these specimens are suitable for using in concussor jaws, and changes in the hardness and microstructures were examined.
Abstract: Purpose – The aim of the research is to investigate the influence of gas metal arc welding on the wear performance of worn concussor jawsDesign/methodology/approach – Worn parts were welded using the gas metal arc welding process Various wires were used for this purpose These welded parts were subjected to wear tests under different loads, and changes in the hardness and microstructures were examined A pin‐on‐disc wear test apparatus was usedFindings – As a result of this study, the following findings are reported: wear rates were significantly increased with the increasing of load and wear distance; the hardness of the weld metal of the welded specimens changed depending upon the chemical composition of the weld wire; with the increasing carbon, manganese and chromium in the weld wire, wear resistance increased; in the present study, specimens B and C showed better wear resistance; therefore these specimens are suitable for using in concussor jawsResearch limitations/implications – Electrodes were
TL;DR: In this article, an innovative methodology for the determination of operational characteristics of journal bearings (j•bs) through using new type charts based upon a numerical solution of the Reynolds equation was introduced.
Abstract: Purpose – This paper aims to introduce an innovative methodology for the determination of operational characteristics of journal bearings (j‐bs) through using new type charts based upon a numerical solution of the Reynolds equation.Design/methodology/approach – The present paper proposes the mapping of the behaviour of a smooth, isothermal and hydrodynamic (j‐b) as a first step towards a future representation of the behaviour of j‐b's with limited length and high lubricating clearance with or without macro or micro topographic features operating under high loads, high temperatures and low linear velocities leading to conditions of mixed or boundary lubrication.Findings – The derived analytical relationships between dimensionless quantities lead to the development of high precision synthetic operational charts regarding sliding j‐b of any given geometry and varying operational characteristics.Originality/value – By considering the iso‐operational curves which are of a hook form relevant to comparative data...
TL;DR: In this paper, the authors obtained the flow restricting capacity by determining their flow coefficients and investigated the unsteady flow with low Reynolds number in the flowrestricting devices such as orifices and capillary tubes having small diameters.
Abstract: Purpose – The main objective of this study was to obtain the flow restricting capacity by determining their flow coefficients and to investigate the unsteady flow with low Reynolds number in the flow‐restricting devices such as orifices and capillary tubes having small diameters.Design/methodology/approach – There is an enormous literature on the flow of Newtonian fluids through capillaries and orifices particularly in many application fields of the mechanical and chemical engineering. But most of the experimental results in literature are given for steady flows at moderate and high Reynolds numbers (Re>500). In this study, the unsteady flow at low Reynolds number (10