What are the consequences of using expired filament for FDM printing?

Using expired filament for FDM printing can lead to several notable issues that impact the quality of the print. As the filament ages, it can absorb moisture from the air, which affects its material properties. This can result in decreased print quality, characterized by issues such as poor layer adhesion, stringing, or bubbling during extrusion. Additionally, the filament may become more brittle over time, leading to increased fragility of the printed parts. When the material is extruded, inconsistencies can arise, causing problems with the flow of filament through the hotend, resulting in uneven extrusion patterns. Therefore, using expired filament clearly has negative consequences on both the mechanical properties of the printed objects and the overall printing process, making this response the most accurate.