Investigating the effectiveness of layer reheating to improve the tensile strength of paused parts manufactured with material extrusion

Components manufactured with fused deposition modeling are prone to failure due to layer delamination, especially when prints are paused between layers. While prior research has demonstrated post-processing-based approaches for addressing layer delamination and improving part strength, little work has tested the effectiveness of in-situ layer reheating, and this study investigates this gap through an experimental study. To investigate in-situ layer reheating, a supplemental heater that can heat a paused layer at a given temperature for a set amount of time was designed and manufactured. A feasibility study was conducted with three variations of a tensile test specimen printed using PLA: (1) a control specimen without pauses or reheating, (2) a paused specimen with a 30-second pause between layers, and (3) a paused reheated specimen with the reheater at 90 °C for 30 s after each pause. Results show that the control specimens were the strongest (17.17 ± 1.44 MPa), followed by the paused, heated specimens (13.03 ± 0.71 MPa), and the paused, unheated specimens (7.44 ± 0.65 MPa). Then, the delamination strength of specimens printed with different pause times (15, 30, and 60 s) and heater temperatures (unheated, 60 °C, 90 °C, and 120 °C) were compared. Delamination strength increased with heater temperature and decreased with pause time. Delamination strength also converged to comparable levels across pause times when the heater was set to 120 °C. Therefore, reheating the paused layer can help regain lost strength due to print interruptions, and there may be optimal heater temperatures based on the material.