Dry Ice Micro Pellet Blasting for sustainable Cleaning of Tungsten Carbide Cutting Tools before PVD Coating

Solid carbon dioxide (CO2) blasting is a promising approach for environmentally sustainable cleaning of tungsten carbide cutting tools after grinding. Past studies have demonstrated the effective cleaning of grinding residues from tungsten carbide with dry ice pellet blasting and the increase of free surface energy with CO2 snow blasting. By that, improved coating properties can be achieved. Dry ice micro pellet blasting is a new approach which mills common dry ice pellets in order to combine the benefits of dry ice pellet blasting and CO2 snow blasting. In this study, process parameters such as standoff distance, blasting angle, blasting pressure, feed rate and mass flow of dry ice particles for dry ice micro pellet blasting are varied and analyzed regarding remaining particle contamination, surface roughness and free surface energy. The effect of process parameter variations on the coating adhesion strength of a subsequent physical vapour deposition (PVD) coating is analyzed. Finally, the results are compared with dry ice pellet blasting and CO2 snow blasting in order to demonstrate that coating adhesion strength can be influenced by variation of blasting parameters.