Correlations of Geometry and Infill Degree of Extrusion Additively Manufactured 316L Stainless Steel Components

Abstract

This study focuses on the effect of part geometry and infill degrees on effective mechanical properties of extrusion additively manufactured stainless steel 316L parts produced with BASF’s Ultrafuse 316LX filament. Knowledge about correlations between infill degrees, mechanical properties and dimensional deviations are essential to enhance the part performance and further establish efficient methods for the product development for lightweight metal engineering applications. To investigate the effective Young’s modulus, yield strength and bending stress, standard testing methods for tensile testing and bending testing were used. For evaluating the dimensional accuracy, the tensile and bending specimens were measured before and after sintering to analyze anisotropic shrinkage effects and dimensional deviations linked to the infill structure. The results showed that dimensions larger than 10 mm have minor geometrical deviations and that the effective Young’s modulus varied in the range of 176%. These findings provide a more profound understanding of the process and its capabilities and enhance the product development process for metal extrusion-based additive manufacturing.

A Review on Material Extrusion Additive Manufacturing of Metal and How It Compares with Metal Injection Moulding

“…However, Srinivasan et al report that the rectilinear pattern provides higher tensile properties than concentric [195]. From the Ultrafuse 316L metal MEX tensile properties reviewed in this work, the rectilinear with 45 • /90 • pattern with appropriate printing parameters (nozzle size, printing speed, strand width, layer thickness and first layer adjustment) reported by Moritzer et al [93] provides higher tensile properties than other infill patterns [66,98] and also similar infill patterns [53,57]. As reported by Singh et al [79], the 0 • /90 • zigzag infill pattern in metal MEX can also provide comparable tensile properties to MIM parts.…”

“…In addition to effects on relative sintered density, Singh et al reported that an increase in the flow rate multiplier up to 120% could improve the surface quality [84]. However, as reported by Rosnitschek et al [98], a too-high flow rate multiplier (200%) results in the deformation of the printed parts because of excessive material. Regarding the layer thickness, most studies report that the thinner layer thickness leads to higher properties [56,68,73,84] due to the reduction of voids between the deposited paths.…”

“…The effect of solid loading content on the shrinkage of 17-4PH stainless steel [8,36,44,49,64,127,158] and 316L stainless steel [9,35,37,38,41,44,45,52,53,56,57,66,68,70,75,98,127,159] with different sintering conditions is summarised in Figures 15 and 16, respectively. The solid loading of 17-4PH is in the range of 55% to 79% with measured shrinkage of 12% to 20% [8,36,44,49,64,158], which is similar to the typical shrinkage obtained in MIM (12% to 20% [127]).…”

“…The sintered properties critically depend on the quality of the as-printed parts. If the as-printed part has a high relative density without any defects, the corresponding sintered [9,35,37,38,41,44,45,52,53,56,57,66,68,70,75,98,127,159].…”

“…Among many adjustable printing parameters for the metal MEX process, there are common variables that have been investigated, for example, printing temperature, printing bed temperature, flow rate multiplier, layer thickness, built orientation, infill pattern and infill density. [9,35,37,38,41,44,45,52,53,56,57,66,68,70,75,98,127,159].…”