Impact of embedding cavity design on thermal history between layers in polymer material extrusion additive manufacturing

By pausing an additive manufacturing process in mid-print, it is possible to create multifunctional structures through strategic insertion of foreign components. However, in polymer material extrusion, previous research has shown that pausing the build decreases the eventual strength of the final part, due to cooling between layers. To better predict this part weakness, this paper seeks to quantify how the toolpath affects the thermal history of a cross-section, thus impacting the formation of weld strength between printed layers. This is pertinent to in-situ embedding as different embedded geometries will require different cavity designs, which, in turn, will affect toolpath design. In-situ thermal measurements are experimentally collected with a thermocouple at the layer interface of structures with different cavity designs. The weld strength between layers is then obtained through tensile tests and theoretically evaluated using polymer weld theory. Results show more accurate predictions of load at failure with this method.