Exploring Ultrasonic Welding As a Means of Improving Structural Design Properties of FFF-Printed Thermoplastics

Abstract Additive manufacturing (AM) is a technology that has improved manufacturing capabilities in a huge variety of industries, as well as increasing rapid prototyping capabilities. Fused filament fabrication (FFF) is one of these technologies, that has seen use in both industry and lab-scale settings to print thermoplastics and polymer matrix composites that have a thermoplastic matrix. However, it suffers from a major flaw in that the strength of printed parts is anisotropic and uneven, creating difficulties when designing parts intended to bear a structural load or face forces from a variety of directions. This study attempts to improve this weakness by introducing an ultrasonic spot welding process to the normal FFF 3D printing method in order to improve the design space available for parts manufactured with this process. Two welding treatments are attempted following different patterns, one where there are overlapping welds to cover as much surface area as possible, and another with no overlapping welds to prevent the risk of damaging or over-welding the part. The samples, as tested by a modified version of ASTM D5528, showed drastically increased maximum fracture load, suggesting a much stronger level of interlayer adhesion. This improved structural property allows for increased design space and potential uses for FFF printed parts in a large variety of industrial and research settings.