Surface waviness effect on machining and wear on engine components

This work investigates how actual surface waviness affects contact between tribological pairs. Samples of different engine cylinders had the surface topography measured, and some non-homogeneity on the surface can be credited to pre-existing waviness location. Some features usually associated with the roughness were indeed caused by pre-existing waviness. Deeper honing grooves correlated with the location of waviness hills, while shallower or even absent honing grooves correlated with waviness valleys. Similar behaviour, i.e., stronger or weaker contact, can be expected during engine operation. To analyse the influence of waviness and the applied filtering, computer deterministic simulations of the lubricated tribological contact under sliding conditions were carried out, considering different cut-off values and different counter-body contact sizes. Results showed that without considering the effect of waviness, hydrodynamic pressures are overestimated, while the boundary contact and asperity pressure can be greatly underestimated. The larger the contact size, the larger the effect of waviness.