Using statistically designed experiment to optimize vacuum-assisted post-processing of binder jetted specimens

Abstract

Purpose This paper aims to propose a vacuum-assisted post-processing method for use in binder jetted technology. The method is based on six key technological parameters and uses standard, commercially available consumables to achieve improvement in tensile strength, as well as the microstructure and porosity of the infiltrated matrix. Design/methodology/approach Six key technological parameters were systematically varied as factors on three levels, using design of experiment, i.e. definitive screening design. Surface response methodology was used to optimize the process and yield optimal tensile strength for the given range of input factors. Thus obtained, the optimized factor settings were used in a set of confirmation runs, where the result of optimization was experimentally confirmed. To confirm improvement in microstructure of the infiltrated matrix, SEM analysis was performed, while the reduction of porosity was analyzed using mercury porosimetry. Findings The obtained results indicate that, compared to its conventional counterpart, the proposed, optimized infiltration method yields improvement in tensile strength which is significant from both the statistical and engineering point of view, while reducing porosity by 3.5 times, using only standard consumables. Scanning electron microscopy examination of fractured specimens’ micrographs also revealed significant morphological differences between the conventional and proposed method of post-processing. This primarily reflects in higher surface area under hardened epoxy infiltrate, which contributes to increased load capacity of specimen cross-section. Research limitations/implications At the present stage of development, the most important limitation of the proposed method is the overall size of models which can be accommodated in standard vacuum impregnation units. Although, in this study, the infiltration method did not prove statistically significant, further investigation is required with models of complex geometry, various sizes and mass arrangements, where infiltration would be more challenging and could possibly result in different findings. Practical implications The most important practical implication of this study is the experimentally verified result of optimization, which showed that tensile strength and matrix microstructure can be significantly improved, using just standard consumables. Social implications Improved strength contributes to reduction of material consumption, which, in a longer run, can be beneficial for environment protection and sustainable development. Originality/value Based on literature review, there have been no previous investigations which studied the tensile strength of infiltrated specimens through design of experiment, which involved specimen preheating temperature, level and duration of vacuum treatment of infiltrate mixture and infiltrated specimens and infiltration method.

Investigating mechanical and thermo-physical properties of binder jet 3D printed elements using a statistical experiment approach

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“…Ocaña-Garz on et al (2020) explored the effect of printing conditions on the infiltration result, which shows that the infiltrant type is significant for the technology. Movrin et al (2019) proposed an optimal post-processing method for 3DP based on six parameters, which will greatly improve the tensile strength of the parts. Impens and Urbanic (2016) addressed that infiltrates can significantly improve the mechanical performances.…”