Investigation of Nd 3 + : YAG Laser Aided Surface Texturing to Improve Tribological Characteristics of Piston Ring

Laser surface processing is increasingly used to improve the tribological properties of sliding surfaces over the last few decades. Texturing in the form of dimples which are evenly spaced helps to reduce friction to a greater extent. But optimizing the size of the dimples with appropriate area density and aspect ratio is a big challenge for the tribologist. This paper aims at the investigation of producing textured surface using nanosecond pulsed Nd3+: YAG laser on the surface of piston rings and also to study its frictional properties using a reciprocating tribometer. Experimental analysis on the effect of diameter area density and aspect ratio of the dimples has been demonstrated to improve frictional performance under different lubrication regimes. Friction tests were carried out with both non-textured and textured piston rings by varying the normal load applied on it using synthetic oil as a lubricant at an oil bath temperature of 180°C. A maximum frictional reduction of up 69% was observed with the nanosecond pulsed laser textured sample at high loading conditions. But nanosecond pulsed laser texturing is always accompanied by recast layer, heat affected zone and micro cracks which may affect the surface properties and in turn the frictional properties of sliding surfaces. Preliminary studies on surface texturing was performed using a femtosecond pulsed laser to improve the surface morphology and tribology characteristics of a piston ring surface.