Parameter correlation study of cylinder liner roughness for production and quality control

Abstract

Surface roughness plays an important role in the control of emissions and friction losses in the cylinder liner—piston ring system as well as securing economically favourable manufacturing. A number of different commercial cylinder liner types have been characterized using traditional two-dimensional stylus and ISO parameters together with the latest three-dimensional characterization. The results highlight the weak and strong correlations between different families of parameters traditionally used for liner surface specifications. The bearing curve based Rxq and Rk parameter families have been evaluated and show systematic and consistent differences when characterizing the same surface features when trying to establish independent characterization of the highly stratified, two-process cylinder liner surfaces. No significant improvement in discrimination results from using ensemble averages. Presentation of correlations in the form of topological diagrams helps to show when parameters with a high intrinsic variability can be effectively replaced by other more robust parameters with which they have a high correlation. Plateau parameters are in general more highly correlated than valley parameters. Three-dimensional parameters show high internal correlations and also correlate highly with some corresponding two-dimensional parameters.