Effect of surface texturing on cast iron reciprocating against steel under starved lubrication conditions: A parametric study

• Micro-textures are produced by laser ablation.
• Geometrical parameters of micro-textures are analyzed using a design of experiments.
• Interaction of parameters is found to have significant effects on the coefficient of friction.
• A new parameter for designing micro-textures is proposed.
• An optimum micro-texture having a low COF and a long lifetime is suggested.

This study investigates the effect of laser surface texturing on the friction behavior and the lifetime of grey cast iron reciprocating under starved lubrication conditions. Five geometrical texture parameters (feature depth, diameter, length, area fraction and sliding direction) were studied using a design of experiments (DoE) approach by developing a fractional factorial design. Reciprocal sliding tests were carried out for the cast iron-steel tribo-pair at a pressure of 24 MPa and a frequency of 6 Hz. DoE results revealed that the geometrical parameters of micro-textures interact in a complex manner. Hence, for better understanding the effect of surface texturing on the tribological performance, the interactions between geometrical parameters need to be considered. It is found that except the following main factors: diameter and area fraction, mainly interactions of geometrical parameters have significant impact on the coefficient of friction. It is also observed that micro-textures could increase the lifetime of tribo-systems sliding under starved conditions. Based on the DoE analysis, an optimum micro-texture having a relatively low coefficient of friction and a long lifetime are achieved with the following (geometrical) parameters: a depth of 50 μm, a diameter of 100 μm, a length of 500 μm, an area fraction of 5%, and the sliding direction perpendicular to the micro-textures.