Fundamentals of Cooling Rate and Its Thermodynamic Interactions in Material Extrusion

Abstract

Material Extrusion (ME) is a layer-by-layer additive manufacturing technique that has gained prominence due to its simplicity, cost-effectiveness, design freedom, and adaptability to a wide range of thermoplastic materials. However, the mechanical performance of ME-printed parts often remains suboptimal, primarily due to complex thermal phenomena that govern microstructural development during the printing process, which are key determinants of mechanical strength. As a result, optimizing thermodynamic printing parameters has become essential for improving the overall quality of the printed parts. Extensive research articles and reviews have been published to explore the effect of many ME printing parameter settings on the resultant product characteristics. Despite this focus, the effect of cooling rate, a critical thermodynamic parameter of the process, has been largely overlooked in current research when they are critically reviewed. Cooling rate plays a central role in determining the thermal history of printed material, which in turn influences polymer chain mobility and microstructural features of the extruded material, all of which are crucial to the mechanical integrity of the printed part. Thus, it has been concluded by this review that analytical and empirical investigations into the influence of cooling rate on the microstructural properties of ME parts represent a valuable and novel contribution to the academic field.