Comprehensive study to evaluate the lifespan of flexible polishing pads by 3D surface characterization technique

The topography of a polishing pad plays a significant role to maintain the effectiveness of the finishing process and to preserve the work surface integrity. 3D surface characterization is an efficient tool to reveal the micro-geometry of the pad. A sequential finishing operation of WC-Co coating is performed by shape adaptive grinding (SAG), and chemical assisted SAG (CA-SAG) using zirconia-alumina polishing pads with mean particle sizes of 125 µm, 80 µm and 60 µm. Coherence correlation interferometry (CCI) is employed to investigate the topography of the polishing pads and to assess the microscopic wear and the lifespan of the pads. A new criterion for selecting the optimum sampling interval is proposed to ascertain the peak density precisely. A comprehensive study is undertaken to quantify and analyse the abrasive wear of the polishing pads after both SAG and CA-SAG by employing 13 advanced 3D surface texture parameters. The density and sharpness of the abrasive particles, the coarseness of the polishing pad, the area and volume of the individual motifs and the bearing and fluid retention properties of the pads are characterized. In the case of CA-SAG, the chemical reagent attacks the backing material of the pads and reduces its effective lifespan as compared to SAG.