Considerations on the surface roughness of SLM processed metal parts and the effects of subsequent sandblasting

摘要

Selective Laser Melting is an Additive Manufacturing technology based on 3D scanning of successive layers of metal powder. Three distinct values were determined for each of the three technological parameters (P - the power of the laser, VSCan - scanning speed and te - exposure time), therefore resulting nine sets for the "layer by layer'" processing. After SLM processing, the samples were sandblasted simply (IS), sandblasted successively (2S), or left unsandblasted (NS). The roughness (Ra) of the outer surfaces was measured for all the samples, and there was found a decrease in the height of the micro-irregularities and the uniformization of the roughness profde along with the intensification of the sandblasting process. For some samples, there were found uncertainties regarding the accuracy of the experimental results' values, determined by the presence of the adherent particles identified by the SEM analysis of the outer surfaces. The number and size of these particles have affected the manner in which the samples were placed on the roughness tester's plate, as well as the accuracy of the measurements. Under these conditions, the tip of the roughness tester's diamond stylus has recorded the specific values of the surface's secondary profile, which is affected by the existence of the formations adhering to the primary profile of the SLM processed samples.