An in-process laser localized pre-deposition heating approach to inter-layer bond strengthening in extrusion based polymer additive manufacturing

Material extrusion-based 3D printing processes have shown importance in the overall development of the field of additive manufacturing and displayed tremendous potential to becoming a cross-cutting tool for research, engineering, developmental work in a wide array of disciplines. In the context of the Fused Deposition Modeling (FDM, one form of Materials extrusion-based 3D printing), one of the main process issues lies in the property anisotropy of parts built using this method, even with process optimization. To address this issue, we report a near-IR laser-based pre-deposition heating method to locally heat up the region of an existing layer near the nozzle before an extrudate comes in contact with the heated region. This in-process approach raises the inter-layer interface temperature to above the critical temperature to increase the interpenetrating diffusion, and therefore the inter-layer bond strength. A 50% increase in the inter-layer bond strength in parts built with this approach is demonstrated. The in-process pre-deposition local heating approach reported here represents an effective means to increase the inter-layer bond strength, and property isotropy of FDM parts. Further, this approach is capable of real-time monitoring and controlling of temperatures at the inter-layer and inter-filament interfaces across the entire volume of a built part, allowing control of the physics of the FDM process to achieve desired mechanical properties.