Improving the Surface Finish and other Properties of Engineering Metal Parts

Abstract

The manufacture of metal parts requires post processing in most cases. These processes include heat treatment for releasing of the residual stresses resulting on the metal surface due to the excessive mechanical forces applies to cut the metal during machining, i.e. milling, turning and drilling. Another example would be the polishing of parts using different techniques. In predominant, polishing is used enhance the part’s roughness to improve the friction coefficient, to give the parts a better view and most important is to adjust the final dimensional accuracy in the microns and sub-microns scale. Traditional polishing methods include the mechanical polishing by using abrasive media or grinding machines, chemical polishing which has the benefit of reaching the inaccessible features although this method requires longer processing time in addition to the impact on environment. Sometimes the thermal deburring method is also applied for the chamfer of sharp edges and corners. In the recent years, the laser polishing technique exhibits interesting efforts and results regarding reproducibility, high control over the processing parameters which allow for the processing of different metals and non-metals materials in addition to the ultrashort processing time. This study is focusing on the laser surface polishing of metal parts, its potentials and limitations. In this study, laser surface polishing using CO2 laser beam irradiation was implemented on stainless steel Additive Manufactured produced surfaces. Two design of experiment models were implemented for the optimization of the main laser input processing parameters. The processing parameters examined were the laser beam power, the scanning speed, the number of laser scan passes, the percentage overlap of the laser tracks between the consecutive passes and the laser beam focal position. The characterization of the measured surface roughness and the modified layer microstructure were carried out using scanning electron microscopy (SEM) and 3D optical.