Showing papers by "Satish V. Kailas published in 2011"
TL;DR: In this paper, the effect of surface texture on the friction was attributed to the variation of the plowing component of friction for different surfaces, and it was also observed that the variations of plowing friction as a function of hardness depends on surface textures.
Abstract: In the present investigation, experiments were conducted by unidirectional sliding of pins made of FCC metals (Pb, Al, and Cu) with significantly different hardness values against the steel plates of various surface textures and roughness using an inclined pin-on-plate sliding apparatus in ambient conditions under both the dry and lubricated conditions. For a given material pair, it was observed that transfer layer formation and the coefficient of friction along with its two components, namely adhesion and plowing, are controlled by the surface texture of the harder mating surfaces and are less dependent of surface roughness (R (a)) of the harder mating surfaces. The effect of surface texture on the friction was attributed to the variation of the plowing component of friction for different surfaces. It was also observed that the variation of plowing friction as a function of hardness depends on surface textures. More specifically, the plowing friction varies with hardness of the soft materials for a given type of surface texture and it is independent of hardness of soft materials for other type of surface texture. These variations could be attributed to the extent of plane strain conditions taking place at the asperity level during sliding. It was also observed that among the surface roughness parameters, the mean slope of the profile, Delta (a), correlated best with the friction. Furthermore, dimensionless quantifiable roughness parameters were formulated to describe the degree of plowing taking place at the asperity level.
73 citations
TL;DR: In this article, the effect of surface texture on the friction was attributed to the variation of the plowing component of friction for different surfaces among the various surface roughness parameters studied, the mean slope of the profile, Delta(a), was found to most accurately characterize variations in the friction and wear behavior.
57 citations
TL;DR: In this paper, the evaluation of coconut and palm oil as lubricants in four-stroke engine was carried out and the performance was compared with commercially available engine oil, the tribological properties of oil samples collected from the engine at regular interval were evaluated by means of four ball tester.
Abstract: In the present work the evaluation of coconut and palm oil as lubricants in four-stroke engine was carried out and the performance was compared with commercially available engine oil. The tribological properties of oil samples collected from the engine at regular interval were evaluated by means of four ball tester. The emissions from engine were monitored by using exhaust gas analyzer. It was observed that antiwear properties of fresh vegetable base oils and engine oil were comparable at ambient conditions. The observed deviation with usage was linked to the oxidation and the absence of additives in vegetable oil. The increased wear with commercial engine oil was due to depletion of additives. Increased fuel efficiency and reduction in the concentration of oxides of carbon and nitrogen in the emission observed with vegetable oil based lubricant was linked to its high flash point.
34 citations
TL;DR: In this article, a mechanism for the formation of friction stir weld is proposed based on experimental results, a synergism of the experimental results with the proposed mechanism is helpful in establishing the set of welding parameters for a given material.
Abstract: Design of the required tool is a key and important parameter in the technique of friction stir welding (FSW). This is so because tool design does exert a close control over the quality of the weld. In an attempt to optimize tool design and its selection, it is essential and desirable to understand the mechanisms governing the formation of the weld. In this research study, few experiments were conducted to systematically analyze the intrinsic mechanisms governing the formation of the weld and to effectively utilize the analysis to establish a logical basis for design of the tool. For this purpose, the experiments were conducted using different geometries of the shoulder and pin of the rotating tool in such a way that only tool geometry had an intrinsic influence on formation of the weld. The results revealed that for a particular diameter of the pin there is an optimum diameter of the shoulder. Below this optimum shoulder diameter, the weld does not form while above the optimum diameter the overall symmetry of the weld is lost. Based on experimental results, a mechanism for the formation of friction stir weld is proposed. A synergism of the experimental results with the proposed mechanism is helpful in establishing the set of welding parameters for a given material.
31 citations
TL;DR: In this paper, various kinds of textures, namely, unidirectional, 8-ground, and random were attained on the die surfaces, and the morphologies of the worn surfaces of the pins and the formation of transfer layer on the counter surfaces were observed using a scanning electron microscope.
22 citations
TL;DR: In this paper, the authors used an inclined pin-on-plate sliding apparatus under both dry and lubricated conditions in an ambient environment to study the response of soft materials during sliding, such as Al-4Mg alloy, high purity Al and pure Mg pins.
Abstract: In the present investigation, soft materials, such as Al-4Mg alloy, high-purity Al and pure Mg pins were slid against hard steel plates of various surface textures to study the response of materials during sliding. The experiments were conducted using an inclined pin-on-plate sliding apparatus under both dry and lubricated conditions in an ambient environment. Two kinds of frictional response, namely steady-state and stick-slip, were observed during sliding. In general, the response was dependent on material pair, normal load, lubrication, and surface texture of the harder material. More specifically, for the case of Al-4Mg alloy, the stick-slip response was absent under both dry and lubricated conditions. For Al, stick-slip was observed only under lubricated conditions. For the case of Mg, the stick-slip response was seen under both dry and lubricated conditions. Further, it was observed that the amplitude of stick-slip motion primarily depends on the plowing component of friction. The plowing component of friction was the highest for the surfaces that promoted plane strain conditions and was the lowest for the surfaces that promoted plane stress conditions near the surface.
16 citations
TL;DR: In this paper, a steel disc is cut using a single point tool and the coefficient of friction of the nascent cut surface is measured by a spherical steel pin situated in close proximity of the point of cutting.
11 citations
TL;DR: In this paper, the friction and wear data of PN/PN pairs in high vacuum environment has been published, where the PN coatings were removed only from the pin surface for all the tests.
Abstract: Although some researchers have published friction and wear data of Plasma Nitride (PN) coatings, the tribological behavior of PN/PN Pairs in high vacuum environment has not been published so far In order to bridge this knowledge gap, tribological tests under dry conditions have been conducted on PN/PN Pairs for varying temperatures of 25, 200, 400 and 500 degrees C in high vacuum (1.6 x 10(-4) bar) environment. The PN coatings showed good wear resistance layer on the ring surface. The PN coatings were removed only from the pin surface for all the tests since it contacts at a point. The friction and wear were low at lower temperatures and it eliminated adhesion between the contact surfaces until the coating was completely removed from the pin surface. (C) 2011 Journal of Mechanical Engineering. All rights reserved.
9 citations
TL;DR: In this paper, unidirectional grinding marks were created on a set of steel plates and sliding experiments were conducted with the prepared steel plates using Al-Mg alloy pins and an inclined pin-on-plate sliding tester.
Abstract: In the present investigation, unidirectional grinding marks were created on a set of steel plates. Sliding experiments were then conducted with the prepared steel plates using Al-Mg alloy pins and an inclined pin-on-plate sliding tester. The goals of the experiments were to ascertain the influence of inclination angle and grinding mark direction on friction and transfer layer formation during sliding contact. The inclination angle of the plate was held at 0.2 deg, 0.6 deg, 1 deg, 1.4 deg, 1.8 deg, 2.2 deg, and 2.6 deg in the tests. The pins were slid both perpendicular and parallel to the grinding marks direction. The experiments were conducted under both dry and lubricated conditions on each plate in an ambient environment. Results showed that the coefficient of friction and the formation of transfer layer depend on the grinding marks direction and inclination angle of the hard surfaces. For a given inclination angle, under both dry and lubricated conditions, the coefficient of friction and transfer layer formation were found to be greater when the pins slid perpendicular to the unidirectional grinding marks than when the pins slid parallel to the grinding marks. In addition, a stick-slip phenomenon was observed under lubricated conditions at the highest inclination angle for sliding perpendicular to the grinding marks direction. This phenomenon could be attributed to the extent of plane strain conditions taking place at the asperity level during sliding. DOI: 10.1115/1.4002604]
8 citations
TL;DR: In this article, the authors investigated the effect of tool angle on welding of sheets of commercially pure aluminum and aluminum alloy AA5052-H32 having different thickness and found that the tool angle plays a major role in the welding process.
Abstract: The technique of friction stir welding (FSW) does offer several advantages over conventional welding techniques. In this paper is presented the results of an investigation aimed at understanding the effect of tool angle on welding of sheets of commercially pure aluminum and aluminum alloy AA5052-H32 having different thickness. The present study demonstrates the feasibility of using friction stir welding (FSW) for joining two different thickness sheets of commercially pure aluminum (t = 1.5 mm and t = 2.0) with sheets of aluminum alloy 5052-H32 having thickness of 1.6 mm and 2 mm. It was found that the tool angle does play a major role in the welding of sheets having different thickness. Formation of the FSW zone was analyzed both macroscopically and microscopically. The tensile properties of the joints were evaluated and correlated with the formation and presence of the FSW zone. From this study it was found that the tool angle for commercially pure aluminum having a thickness of 1.5 mm and 2.0 mm is 2.580. The tool angle is 1.910 for the sheets of AA 5052-H32 having a thickness of 1.6 mm and 2 mm. The joint efficiency of the friction stir welded AA 5052-H32 was 87.5 pct. when compared to the base material. The hardness was also observed to drop in the region of the weld. Key words: Friction stir welding, tool angle, aluminum alloy (AA5052-H32), Hardness, macrostructure, microstructure.
6 citations
01 Jan 2011
TL;DR: In this article, a sliding tester was used to study the different frictional responses of materials with varying crystal structure and hardness during sliding against a relatively harder material of different surface textures and roughness.
Abstract: In the present investigation, efforts were made to study the different frictional responses of materials with varying crystal structure and hardness during sliding against a relatively harder material of different surface textures and roughness. In the experiments, pins were made of pure metals and alloys with significantly different hardness values. Pure metals were selected based on different class of crystal structures, such as face centered cubic (FCC), body centered cubic (BCC), body centered tetragonal (BCT) and hexagonal close packed (HCP) structures. The surface textures with varying roughness were generated on the counterpart plate which was made of H-11 die steel. The experiments were conducted under dry and lubricated conditions using an inclined pin-on-plate sliding tester for various normal loads at ambient environment. In the experiments, it was found that the coefficient of friction is controlled by the surface texture of the harder mating surfaces. Further, two kinds of frictional response, namely steady-state and stick-slip, were observed during sliding. More specifically, stead-state frictional response was observed for the FCC metals, alloys and materials with higher hardness. Stick-slip frictional response was observed for the metals which have limited number of slip systems such as BCT and HCP. In addition, the stick-slip frictional response was dependent on the normal load, lubrication, hardness and surface texture of the counterpart material. However, for a given kind of surface texture, the roughness of the surface affects neither the average coefficient of friction nor the amplitude of stick-slip oscillation significantly.
TL;DR: In this paper, the axial force during friction stir welding is sensitive to plunge depth of the tool and is one of the prime factors which exercises control over heat generation during welding.
Abstract: The axial force during friction stir welding is sensitive to plunge depth of the tool and is one of the prime factors, which exercises control over heat generation during welding. Consequently, the plunge depth for a given tool rotation speed, traverse speed, material and test machine needs to be optimized so as to get a defect-free weld. In this paper, we present and briefly discuss the results of an elaborate and enriching investigation aimed at understanding the extrinsic influence of plunge depth of the tool on weld formation in aluminium alloy 7020-T6 for a range of rotation rate and traverse speed and using two different tools. The critical need for use of a scientific approach to optimize plunge depth for a given tool material and test machine in fewer number of steps is emphasized. Key Words: Friction Stir Welding, Tool Plunge, Rotation speed, Traverse speed, Aluminium Alloy 7020
01 Jan 2011
TL;DR: In this paper, the effect of surface texture of soft materials on friction during sliding against hard materials was studied using an inclined scratch testing system, and it can be inferred that the surface textures of both harder and softer materials are important in controlling frictional behavior.
Abstract: Surface texture influences friction during sliding contact conditions. In the present investigation, the effect of surface texture of soft materials on friction during sliding against hard materials was studied using an inclined scratch testing system. In the experiments steel balls were slid against aluminum alloy flats of different surface textures and roughness. The surface textures were classified into unidirectional, 8-ground and random. Analysis of the experimental data showed that the friction depends on the softer materials surface texture under both dry and lubricated conditions. The results were also compared with aluminum alloy slid against steel flats of different surface textures and roughness. From the experiments, it can be inferred that the surface textures of both harder and softer materials are important in controlling frictional behavior.
TL;DR: In this article, the tribological properties of PN rings were examined in high vacuum environment (16 x 10-4bar) at 25°C, 200°C and 400°C.
Abstract: The tribological properties of Plasma Nitrided (PN) rings were examined in high vacuum environment (16 x 10-4bar) at 25°C, 200°C and 400°C The high vacuum based pin on disc tribometer was used for this investigation The two different sliders namely austenitic stainless steel type AISI 316LN (316LN) pin and Nickel based alloy coated (Colmonoy) pin have been used The tribological parameters such as friction coefficient, wear mechanism and wear rate have been evaluated The PN 316LN rings exhibits excellent wear resistance against 316 LN pin and Colmonoy pin at all temperatures However, the PN 316LN ring vs Colmonoy pin pair shows better wear resistance than PN 316LN ring vs 316 LN pin pair Whereas the untreated 316 LN ring vs 316 LN pin pair exhibits the combination strong adhesion and plastic deformation wear mechanism
01 Jan 2011
01 Jan 2011
TL;DR: In this paper, various kinds of textures, namely, unidirectional, 8-ground, and random were attained on the die surfaces, and they were then slid against steel plates for various numbers of cycles using a pin-onplate reciprocating sliding tester.
Abstract: In the present investigation, various kinds of textures, namely, unidirectional, 8-ground, and random were attained on the die surfaces. Pins made of aluminum were then slid against steel plates for various numbers of cycles using a pin-on-plate reciprocating sliding tester. It was observed that the friction and transfer layer formation depended on the die surface textures. Under lubricated conditions, the friction decreased for unidirectional and 8-ground surfaces but increased for random surfaces as a function of cycles. Under dry conditions, the friction increased with increasing number of cycles for all kinds of surfaces. In the tests, the friction was always highest when sliding was perpendicular to the unidirectional textures and was lowest for the random textures under both dry and lubricated conditions. The difference in friction values between these two surfaces decreased with increasing number of cycles. The variation in the friction was attributed to the change in texture of the surfaces during sliding.