Multi-variable Optimization of the Shot Blasting of Additively Manufactured AlSi10Mg Plates for Surface Roughness Using Response Surface Methodology

Direct metal laser sintering (DMLS) technique of additive manufacturing has been proven to be the best technology for printing metallic components with higher density and better mechanical properties. However, due to higher surface roughness of the as-built metallic components, post-processing through shot blasting is the most recommended method for improving surface finish. In the present work, the optimum shot blasting conditions were explored for achieving desired surface roughness for the DMLS printed AlSi10Mg aluminum alloy plates. Three input parameters (viz., time, pressure and grit size) selected at three levels were used to formulate the design matrix. Consequently, 30 real-time shot blasting experiments were performed, and the results obtained as surface roughness were used to develop the quadratic model using response surface methodology. Further, the prediction effectiveness was verified using analysis of variance. The experimental results revealed that the effect of blasting pressure on the surface roughness was found to be positive and most significant (41.89%), followed by the negative influence of time of shot blasting (29.29%) and grit size of shots (23.71%). The predicted values of surface roughness (maximum and minimum) obtained at optimum set of process parameters were found to be in agreement (± 6%) with the experimentally measured data. The variations in surface roughness were further validated through scanning electron microscopy. The proposed mathematical model is effective, precise and promising for the prediction of surface roughness in the shot-blasted surfaces of additively manufactured aluminum alloys.