Influence of bed temperature on the final properties of PLA parts manufactured by material extrusion

Purpose This paper aims to study the influence of bed temperature on the properties of printed parts and their structural stability. Design/methodology/approach Material extrusion is a manufacturing technique in which a part is completed layer by layer with molten filament. The first layer is deposited on a build platform called bed, which is usually at a controlled temperature above room temperature. The density, coefficient of thermal expansion and Young’s modulus were determined as a function of the bed temperature. The complex permittivity was determined at different temperatures, with the aim of analyzing the influence of the bed temperature and isothermal treatments on the characteristics of the amorphous phase. Findings The Young’s modulus presented a non-monotonic behavior, while the coefficient of thermal expansion did not present a clear dependence on the bed temperature. However, a contraction of the dimensions of the parts was observed after heating at temperatures above the glass transition. With treatments at temperatures lower than the glass transition temperature, no changes were observed. However, with treatments at temperatures higher than this, changes in the mobile amorphous region were inferred. Originality/value Issues related to the use of parts manufactured by 3D printing after a posterior heating were analyzed: an improvement in the Young’s modulus and a slight variation of the coefficient of thermal expansion were observed. However, a significant variation in dimensions was detected, mainly for the lowest bed temperatures. This is important for possible applications at temperatures above 60°C.