Effect of reaming on surface properties of self-lubricating composites

This paper has the main objective to analyze the influence of the reaming process on surface properties (topography, affected layer and tribological performance) of self-lubricating composites. Tests were performed with constant cutting parameters—cutting speed (vc = 20 m/min), feed (f = 0.3 mm/rev.) and depth of cut (ap = 0.25 mm). The materials are composites with solid lubricants (6.5%vol of graphite and 1%vol of h-BN—hexagonal Boron Nitride) mixed in a Fe–4Ni–0.5Si alloy manufactured by pressing and sintering. The surfaces analysis showed that the reaming process significantly modified the surfaces, reducing the percentage of pores + solid lubricants by approximately 15% compared with the sintered surfaces. The reaming process had a great influence on the anisotropy of the surface, as well as in the roughness parameters Sz (maximum height), Sbi (bearing surface index), Sk (core height), Ssk (kurtosis) and Ssk (skewness). The friction coefficient of the reamed surface stayed below the lubricity limit (μ < 0.2). The reamed surfaces presented a friction coefficient of around 62.5% and wear rate approximately 560% higher than the sintered surfaces.