Compressive deformation analysis of large area pellet-fed material extrusion 3D printed parts in relation to in situ thermal imaging

Abstract

In large area pellet extrusion additive manufacturing, the temperature of the substrate just before the deposition of a new subsequent layer affects the overall structure of the part. Warping and cracking occur if the substrate temperature is below a material-specific threshold, and deformation and deposition adhesion failure occur if the substrate temperature is above a different threshold. Currently, Big Area Additive Manufacturing (BAAM) machine users mitigate this problem by trial and error, which is costly and may result in decreased mechanical properties, monetary losses and time inefficiencies. Through thermal imaging, the range of temperatures present during the printing of a 20 wt. % carbon fiber reinforced acrylonitrile butadiene styrene (ABS-20CF) single-bead vertical wall via the BAAM machine was measured. Compression tests were performed to understand the material behavior at those temperatures. Optical imaging was performed to identify a relationship between porosity in the printed bead and plateau regions in the compression curves at temperatures of 170 °C and below. From the thermal imaging and compressive testing, it was concluded that if the substrate temperature is above 200 °C, it will not be able to withstand the load exerted by the deposition of a new layer without experiencing deformation. This behavior was attributed to the experimentally obtained low compressive strength of ABS-20CF observed at temperatures above 200 °C.