New Methodology for Automatic Process Parameters Optimization in Selective Laser Melting

Selective laser melting is one of the most promising additive manufacturing technologies, thanks to its capability to manufacture complex shaped parts with good dimensional accuracy and high mechanical performance. In recent years, this technique is starting to be adopted for the production of end-use parts, addressing high quality requirements. To achieve the desired quality of the final product it is necessary to optimize the process parameters, possibly by reducing the build time needed for its production. However, the currently available process optimization methodologies are very time consuming and there is a lack of standards. The aim of this work is to develop an automatic, reliable and objective process optimization technique, which can be employed to find optimal parameters combinations for different process conditions. Therefore, it has been developed an experimental approach, based on single tracks analysis and on 3D benchmarks characterization. The main novelty of this optimization method is the automatization of samples analysis, which entailed the adoption of innovative surface metrology techniques and of novel algorithmic frameworks developed in MATLAB environment. According to the novel method, the effects of laser power (P), scan speed (v) and laser spot size (ds) have been investigated for the two most used materials; the extra-low-interstitial grade of Ti6Al4V alloy and the 316L stainless steel. Hence, P-v optimal combinations has been defined for each spot size level investigated, finding a first optimal region in single tracks analysis and then identifying the optimal parameter set for 3D components production. This methodology has allowed the definition of multiple optimal parameter sets in an automatic way, limiting time and material waste. Therefore, it can be adopted in all existent production strategies that require more than one process parameter set and could allow the development of new production approaches.