Effects of in-process surface finishing on part strength in polymer material extrusion additive manufacturing

Material extrusion additive manufacturing suffers from limitations in surface finish, dimensional accuracy, and part strength. Hybrid manufacturing, which in this context integrates material extrusion with in-process surface finishing, offers a potential solution to address these issues. This study presents two critical aspects of a polymer-based hybrid manufacturing process. First, it quantifies the impact of the interfacial temperature drop during the finishing cycle on part strength. Secondly, it investigates the influence of surface finishing on part strength, considering two finishing methods: machining and a combination of machining and chemical polishing. The results reveal that temperature plays a major role in influencing the part strength and must be regulated to preserve interfacial bonding. An interfacial temperature drop beyond the material’s glass transition temperature can lead to a 50% reduction in part strength. However, slowing down the printing speed at the interface could induce localized heating, partially offsetting this loss. Furthermore, in-process surface finishing can mitigate potential sites for crack initiation, thereby increasing part strength. The results indicate that the machining-only scenario increases the part strength by 70.6% compared to the as-printed condition, while the combined machining and chemical polishing further increase part strength by 163.3%. This research underscores the multifaceted benefits of surface finishing in a polymer hybrid manufacturing setting while highlighting the potential challenge of temperature management.