Influence of SLM block support design on geometrical quality of AISI 316 l cantilever features and its impact on post-processing

Abstract

In Selective Laser Melting, the design of efficient support structures is the key enabling the production of high-quality functional parts exhibiting complex shapes with improved geometrical accuracy. Nonetheless, from a process point of view, supports are waste material that must be minimized to reduce production costs and post-processing. Despite the recent technological advances, support optimization is based on time- and resource-consuming trial-and-error experimental campaigns, while support removal is primarily a manual operation which requires a consistent human effort and consumable consumption. Nowadays, the industry is demanding a tool capable to optimize support design and placement based on part geometry and building orientation, by ensuring high part geometrical accuracy along with reduced timing for post-processing operations. 
This research work is the starting point of a wide research activity aiming to design and develop a software tool for the automated engineering and implementation of optimized support structures based on both part and process requirements. Specifically, the influence of the support thickness and the tooth length on the final geometrical quality of AISI 316L cantilever features and on the post-processing phase (i.e., support removal) is analysed. The experimental results show that the support thickness strongly affects the final part distortion, reducing the as-built geometrical deviation by 72.6% when wall thickness increases up to 0.7 mm. On the contrary, tooth length reduces the post-processing time up to 40.5% and the usage of consumables up to 72.7% when decreased from 0.7 mm to 0.3 mm. 
The achieved results highlight that the implementation of optimized support structures ensuring low geometrical deviation and involving reduced resource consumption in post-processing is feasible. These findings provide the starting design rules for the engineering of an empirical methodology, based on thermomechanical modelling, enabling optimized design and implementation of SLM support structures.