NATIONAL TRIBOLOGY CONFERENCE 24-26 September 2003 THE ANNALS OF UNIVERSITY “DUNĂREA DE JOS “ OF GALAŢI FASCICLE VIII, TRIBOLOGY 2003 ISSN 1221-4590 208 TRIBOLOGICAL CHARACTERISATION OF SURFACE TOPOGRAPHY USING ABBOTT-FIRESTONE CURVE Minodora Rîp ă , Lorena Tomescu, Mioara Hapenciuc, Ion Crudu University “Dunărea de Jos” of Galati, România minodora.ripa@ugal.ro ABSTRACT The majority of the roughness parameters allow general description of the surface topography. For tribological characterisation of surface topography, analyses based on Abbott-Firestone Curve give useful information about some special functioning properties as bearing, sealing and lubricant retaining capabilities. The paper presents the results of roughness analyses for the worn surfaces of steel rollers, obtained after rolling/sliding wear tests. KEYWORDS: topography analysis, Abbott-Firestone curve. 1. INTRODUCTION For many engineering applications the surfaces are manufactured in order to get some special functio- ning properties as bearing, sealing and lubricant retaining capabilities. These surfaces may be designed to have specific topographical features that are beneficial for specific functioning applications. The majority of the roughness parameters allow general description of the surface topography. Nevertheless it is more efficient and useful to analyse specially defined parameters for describing the particular chraracteristics of a surface, that are important for a certain application). Traditional roughness parameters as R a and R q are seen to be concerned only with relative departures from the mean line in the vertical direction; they do not provide any information about the shape, slopes and sizes of the asperities or about the frequencies of their occurrence [1]. It is possible to have the same R a and R q values for surfaces of widely different materials and profiles (fig. 1). Unworn surface, R a =2,4µm Worn surface, R a =2.4µm Fig. 1 Different worn surfaces, same R a [2]. Measuring digital devices make possible to explore more sophisticated but appropriate parameters in order to obtained quantitative and qualitative criteria for improving selection of working regimes, materials and manufacturing processes. 1.1. The Abbott-Firestone Curve A function named the curve of the bearing ratio (or the Abbott-Firestone curve or bearing area curve) is defined for a profile by national and international standards. The Romanian standard includes this curve among the relative parameters of the roughness and the parameters referring to the irregularities of the profile. Digital devices for roughness measurements automatically plot this curve. One of the advantages for studying surfaces by the help of Abbott-Firestone curve is that it could simulate the wear effects and the running-in process. Furthermore, this curve gives information about the material and void volumes characterising the surface topography and more recently it could be useful for defining and using functional parameters in 3D analysis [1, 3]. 1.2. Analysing the Abbott-Firestone curve The functional analysis of the surfaces with the profile bearing length ratio was initiated in 1933 by Abbott and Firestone. Three parameters were extrac- ted from the Abbott-Firestone curve. The peak rough- ness was defined as the range of heights embracing 2- 25% of the bearing length while the medial and valley roughness were defined to cover 25-75%, 75-98% of the bearing length, respectively [1]. The standard DIN 4776 formally standardised the R k parameter set, based on three zones classification of the Abbott-Firestone curve. This set