Impact of multiple infill strategy on the structural strength of single build FDM printed parts

Fused Deposition Modeling (FDM) technology manufactures the functional prototypes of different thermoplastics and is among the most popularly used technique of additive manufacturing. Filling pattern is one of the reputable parameters in FDM, defined as the internal printed structure of parts; mainly influences the part's strength and its mechanical properties, print time, print quality, and weight. Filling patterns are categorized as internal and external infill patterns and different arrangements such as honeycomb, rectangular, triangular, rectilinear, etc. are available for both categories. In this article, a strategy based on the joining of different infill patterns in a single build part is used to validate the impact of this approach on the strength-to-weight ratio and cost of the manufactured part. Honeycomb, rectilinear, triangle, and rectangular patterns were chosen as individual infills and all possible combinations of these patterns have been examined. The time and material required to build a part are noted from the slicing software to estimate the cost of printed parts. To evaluate the strength-to-weight ratio, tensile testing has been performed. Experimental results have shown that the combination of rectangular and triangular patterns gives a 13 %, 20 %, 27 %, and 4 % increase in strength-to-weight ratio in comparison with rectilinear, triangular, rectangular, and honeycomb individual infills, respectively. Based on the comparative study of obtained results, a rectangular infill combination with a triangle pattern is suggested; which has an optimum strength-to-weight ratio along with minimal production cost, and is recommended for Fused Deposition Modeling.