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The effect of cylinder liners on engine performance is substantial. Typically, the cylinder surfaces were plateau honed. However, recently additional dimples or grooves were created on them. This work discusses the tribological impacts of textured cylinder liner surfaces based on a review of the literature. The results of the experimental research obtained using test rigs and fired engines were critically reviewed. In addition, the results of the modeling are shown. Circular oil pockets and grooves perpendicular to the sliding direction of piston rings of small depths were typically used. Surface texturing of the cylinder liners governs lubrication between the cylinder liner and the piston ring by an increase in oil film thickness near the reversal points leading to reductions in friction force and wear and in the fired engine to a decrease in fuel consumption and to an increase in power or torque. The correct texturing pattern ensures a decrease in the oil consumption, blow-by, and emissions of the internal combustion engine compared to plateau-honed surfaces. Considerations of future challenges are also addressed. The volume of lubricant reservoir in surface topography, called oil capacity, should be a substantial parameter characterizing textured surfaces. [ABSTRACT FROM AUTHOR]

Mechanical losses consume about 40% of the total energy developed by a typical automotive engine. The piston–cylinder system accounts for 50% of the engine frictional losses, of which 70% to 80% is attributed to the piston rings. Inadequate lubrication in the parts of the engine reduces the reliability of engines, since high wear, seizure, or catastrophic failure of the components may occur. Moreover, frictional losses adversely affect the economic use of fuel. Therefore, a marginal reduction in frictional losses enables economic fuel consumption and is a significant achievement. Of the various factors, the surface topography of the piston rings and cylinder liner dominates the lubricant flow between them and influences its tribological behaviour. Surface texturing, lubricant formulation, and lubricant additives have undergone significant technological advancements in recent times to satisfy the global requirements of reduced emission and improved fuel economy. One of the emerging technologies for significant improvement in the tribological properties of mechanical components is laser surface texturing. The precise control of the shape and size of the textures (dimples or grooves) and rapid processing rate makes laser surface texturing advantageous. This article reviews the theoretical and numerical methodologies developed to analyse the impact of surface texturing on the friction behaviour of piston ring–cylinder liner contact. In addition, the article presents future directions for the research work on improving the tribological performance of internal combustion engines. The present Part 1 of the article discusses the laser surface texturing process, and Part 2 reviews its use in piston ring–cylinder contact. [ABSTRACT FROM AUTHOR]

Laser surface texturing (LST) is widely explored for modifying the surface topography of various materials. In this study, a detailed investigation of laser textured surfaces produced on austenitic stainless steel (AISI 304) was carried out. Three different textures (square, parallel, perpendicular) were produced by a Ti sapphire laser. The processed surfaces were characterized by surface morphology, phase structure, microhardness, surface roughness, and wettability. A ball-on-disk tribometer was used to study the tribological performance of both untextured and textured samples. The experimental observations demonstrate that LST improves both surface wettability and surface roughness. Average surface roughness (Ra) was increased by 350% and the contact angle was reduced from 43° to 22°. The textured surfaces show a lower coefficient of friction and better wear resistance than the untextured surface. Out of the investigated patterns, the square textures exhibited a maximum reduction of 68% in the friction coefficient and a 50% lower wear rate. [ABSTRACT FROM AUTHOR]

This numerical study predicted wear of lubricated total knee replacements with the existing of textured surface and the possibility of surface designs to reduce wear. In the first part, a wear model of metal-on-polyethylene total knee replacement was developed. The medial and lateral knee compartments was accounted for separately, with the contact force and motion during walking cycles applied. An adapted Archard wear formula was employed where the wear factor was an exponential function of the ‘Lambda ratio’ (film thickness to the average roughness). Wear of the soft bearing surface (polyethylene insert) was simulated with regularly geometry update until a steady-state wear observed. In the second part, the effect of surface topography of the knee replacements was investigated. The surface texturing techniques have shown promising benefit to machine components in many areas of engineering practice. The texture parameters were designed using the Taguchi method for the geometry, size, and distribution of the micro dimples. It was observed that the lateral compartment may benefit from surface texturing if dimples were properly designed, while the texturing showed hardly advantageous effect on the medial surface in terms of lubrication enhancement and wear reduction. Some results were presented in the 6th World Tribology Conference.

The frictional capacity of rubber-tired metros decreases over time under the action of metro traffic. It is well known that the texture of rolling tracks contributes to evacuate water from the tire/track interface and generate friction forces. There is then a need to understand the evolution under traffic of the texture of rolling tracks to optimize their maintenance in terms of surface texturing. This paper investigates the friction and wear of steel rolling tracks subjected to laboratory polishing tests. Specimens are extracted from real metro tracks. Different initial textures obtained from different initial treatments of the surfaces are studied. Polishing and friction measurements are performed. During the polishing process, the surface topographies are measured at different polishing states and functional volumes and texture descriptors evaluated. Results show that the surface asperity's height and sharpness decrease with the number of polishing cycles. Also, the wear characterized by the difference in terms of material volumes between the initial and polished states, increases with the polishing duration. This evolution is composed of two phases corresponding respectively to transient and stationary wear. The evolution of wear volume during the stationary phase is in agreement with Archard's wear law. Tight correlation is found between friction and wear volume. [ABSTRACT FROM AUTHOR]

Laser surface texturing is a powerful tool to fabricate functional surface textures, whereby their morphology and cross‐sectional profile greatly depend on laser parameters such as pulse duration and fluence. In this work, the authors fabricate well‐defined groove‐like textures on stainless steel by laser surface texturing using different pulse durations ranging from nano‐ to femtoseconds, while keeping structural parameters such as depth and periodicity fairly constant. By doing so, the influence of the pulse duration on the resulting cross‐sectional profile of the textures and its subsequent impact on the tribological response are assessed. Reciprocating ball‐on‐disk tests and computational fluid dynamic simulations with Abaqus are used to evaluate the tribological performance of the as‐fabricated textures. Their results demonstrate that the use of laser pulses with different pulse durations induce changes in the resulting cross‐sectional profiles with the formation of rims/bulges well as the occurrence of recast phenomena and debris accumulation for nanosecond laser pulses. Decreasing the pulse duration significantly reduces the heat affected zone and the thermal damage, as well as avoided the formation of rims/bulges. Reciprocating ball‐on‐disk tests demonstrated that the differences in the cross‐sectional profiles have a significant influence on friction and wear behavior of the textured surfaces. The tribological properties of surface textures fabricated with different laser pulse durations ranging from nano‐ to femtoseconds are investigated. The influence of the pulse duration on the textures' profile and its impact on the tribological response are assessed. Their results demonstrate that laser pulse duration has a significant influence on the topography of surface textures and thus the frictional response. [ABSTRACT FROM AUTHOR]