The effect of process parameters on tensile behavior of 3D printed flexible parts of ethylene vinyl acetate (EVA)

Fused deposition modeling (FDM) is widely accepted AM process due to its capability of fabricating intricate geometries using filament of thermoplastic materials such as ABS, PLA, etc. Due to the limitations of the filament feed extrusion mechanism, existing FDM systems cannot fabricate flexible parts of soft-elastomers. Instead of filament shape, the material in pellet form has a broad scope for 3D printing of flexible parts. Ethylene vinyl acetate (EVA) material is widely used for the fabrication of flexible objects; however, the potential of this material has not been explored yet using the FDM process. In this study, flexible specimens of EVA material have been printed using a customized pellet based FDM system followed by the investigation on the effect of process parameters on tensile behavior. The effect of process parameters namely barrel temperature, platform temperature, build orientation, raster angle and number of contours have been studied on the tensile properties namely, ultimate tensile strength and % elongation at break. Response surface methodology (RSM) and analysis of variance (ANOVA) techniques have been used to study the effect of process parameters for attaining optimum tensile properties. It was found that barrel temperature, raster angle, and platform temperature affect the tensile behavior of EVA specimens significantly. The maximum obtained values of ultimate tensile strength and elongation at break were 8.83 MPa and 522.34% respectively. The outcome of the current study will help the engineers and designers to predict the tensile behavior of flexible parts for various applications.