THE ANNALS OF “DUNĂREA DE JOS” UNIVERSITY OF GALAŢI FASCICLE V, TECHNOLOGIES IN MACHINE BUILDING, ISSN 1221- 4566, 2012 13 USING 3D NON-CONTACT PROFILOMETRY FOR EVALUATING WEAR TRACKS Constantin Georgescu 1 , Razvan Şolea 2 , Lorena Deleanu 1 1 Machine Design and Graphics Department, “Dunarea de Jos” University of Galati, Romania 2 “Dunarea de Jos” University of Galati, Romania constantin.georgescu@ugal.ro ABSTRACT This paper presents a new method for evaluating wear tracks with the help of 3D profilometry. Using a non-contact profilometer, every wear track and its surrounding zones are recorded as a matrix, each element being given as z(x, y), z being the height of the surface in the point characterized by the position (x, y). It is described a method of identifying the limits of the wear track based on curvature radii variation, characterizing each line recorded by the profilometer. The designed pseudo code provides accurate values for the wear track area and volume. KEYWORDS: 3D profilometry, wear track, pseudo code 1. INTRODUCTION The functioning of triboelements made of polymeric materials requires maintaining working parameters in allowable ranges. The damages due to friction and wear processes are complex and they are the results of overlapping processes: wear, elasto-plastic deformation, expansion, shrinkage, fatigue processes, etc. [3, 8, 10, 11, 13, 15] In many research works related to wear and especially those involving the block-on-ring tester [6], the volume of lost material is evaluated by calculation, starting from records of different parameters, such as: - the mass loss (Δm), knowing the material density (ρ); - the approach between the triboelements, (Z), recorded by the tribometer [3, 12]; - the width of the wear track (b), usually measured after the test ends. The authors noticed that the mass loss is very small (tenth of miligram) as compared to the mass loss of a block made of PTFE for the same testing conditions. Also, when calculating the linear wear of the width of the wear track , there are aspects that are not taken into account, such as the macrogeometrical deviations (the flatness deviation, the cylindricity deviation of the ring, etc.) and the divergence in positioning the triboelelements at test start or, more, their deviation in time due to functioning [1, 4, 7]. 2. METHOD FOR EVALUATING THE VOLUME OF THE WEAR TRACK When comparing the values for two wear parameters, the volume determined from the mass loss of the block and the volume calculated with the approach between the two triboelements, the authors noticed differences (see Table 1). And this is why they try to evaluate the wear by a new parameter: the volume of the wear track. This original method is based on the literature for 3D profilometry [2, 5, 9, 14], recording the surface topography of the tested blocks with the help of a 3D profilometer. The data are included in a set of coordinates X, Y, Z of the surface topography and then this set is used for calculating the volume of the wear track using the program MatLab R2009b. For calculating the area and the volume of the wear track taking into account the data obtained by measuring the already tested blocks, the following steps are to be done: • eliminating the block zones that are not near the wear track (Fig. 1 presents the reconstruction of the block based on the coordinates recording); • recognizing the wear track limits; Calculating the area and the volume of the wear track.