Extrusion-based additive manufacturing process for producing flexible parts

The processing of elastomers through fused deposition modeling (FDM) is challenging task due to low column strength and high melt viscosity. Ethylene vinyl acetate (EVA) is an elastomer which is widely used for fabricating flexible objects. However, the potential of this material has not been explored in the FDM process. Pre-fabricated EVA filament cannot be processed in standard filament feed extrusion mechanism of commercial FDM machine due to buckling of the filament. However, development of pellet-based extrusion additive manufacturing (AM) may eliminate the issues caused by elastomer filament. The current study demonstrates the development of pellet-based AM system for processing EVA material. The developed system is compatible with the three-axis CNC milling machine, which provides high precision positioning to the deposition path and required power for screw rotation. Details about hardware and software related to the developed system have been presented. Flexible parts using EVA pellets have been fabricated successfully, which shows the capability of the developed extrusion AM system. Experiments have been performed for tuning process parameters. Further, mechanical characterization has been done to analyze the dimensional accuracy, flexibility, strength and hardness of printed parts. Obtained results show that EVA demonstrates approx. 300-550% higher elongation as compared to ABS and PLA materials, which indicates EVA can be used to make highly flexible parts. The outcome of this study will be helpful to the engineers for the development of low-cost flexible parts for those applications where customized flexible parts are needed in short span of time.