The Effect of Annealing on Additive Manufactured ULTEM™ 9085 Mechanical Properties

Abstract

Fused filament fabrication (FFF) is increasingly adopted for direct manufacturing of end use parts in an aviation industry. However, the application of FFF technique is still restricted to manufacturing low criticality lightly loaded parts, due to poor mechanical performance. To alleviate the mechanical performance issue, thermal annealing process is frequently utilized. However, problems such as distortion issues and the need for jigs and fixtures limit the effectiveness of the thermal annealing process, especially for low volume complex FFF parts. In this research, a novel low temperature thermal annealing is proposed to address the limitations in conventional annealing. A modified orthogonal array design is applied to investigate the performance of ULTEM™ 9085 FFF coupons. Further, the coupons are annealed with specialized support structures, which are co-printed with the coupons during the manufacturing process. Once the annealing process is completed, multiscale characterizations are performed to identify the mechanical properties of the specimens. Geometrical measurement of post annealed specimens indicates an expansion in the layering direction, which indicates relief of thermal stresses. Moreover, annealed coupons show an improvement in tensile strength and reduction in strain concentration. Mesostructure and fracture surface analysis indicate an increase in ductility and enhanced coalescence. This research shows that the proposed annealing methodology can be applied to enhance the mechanical performance of FFF parts without significant distortion.

A Comparative Analysis of Chemical, Thermal, and Mechanical Post-Process of Fused Filament Fabricated Polyetherimide Parts for Surface Quality Enhancement

“…In terms of dimensional accuracy, specimens subjected to thermal annealing suffered the most remarkable transformation: they all expanded in the building direction (an average of 0.5 mm in height) and contracted in the remaining directions (1 and 5 mm in width and length, respectively). This correlates with the theory proposed by Zhang et al [ 30 ] concerning the relaxation of thermal stresses created in the building direction, which seems to be valid at temperatures higher than the material’s T g as long as exposure is maintained within the herein presented ranges. It is also noteworthy to mention that higher temperatures induce more significant dimensional changes.…”

“…A relevant study concerning the post-processing of polyetherimide (PEI) parts was recently presented by Zhang et al [ 30 ]. They used thermal annealing to post-process the samples and noted a relaxation of thermal stresses when PEI specimens were treated for long periods at temperatures only below its T g .…”

Effects of Functional Fillers in the Mechanical Properties of 3d-Printed Polylactic Acid Using Fused Deposition Modelling

“…PLA suffers considerable changes at low temperature such as 70 °C, while higher temperature at 110-170 °C. According to tests, this induces bending, shrinkage, and even complete melting [130].…”

Experimental Investigation of Additive Manufacturing of Continuous Carbon Fiber Composites with Multifunctional Electro-Tensile Properties

“…Different AM techniques are available and the most commonly used AM technique is the fused filament fabrication (FFF) method. While the tensile strength of the 3D printed coupons was addressed, the experimental investigation of additive manufacturing of continuous carbon fiber composites as well as the electro-tensile multifunctional properties was not included [ 1 ]. An open-source FFF printer was used for 3D printing short fiber reinforced nylon filament to study the effects of low-temperature thermal annealing on the 3D printed Ultem 9085 structural properties [ 1 ].…”

“…While the tensile strength of the 3D printed coupons was addressed, the experimental investigation of additive manufacturing of continuous carbon fiber composites as well as the electro-tensile multifunctional properties was not included [ 1 ]. An open-source FFF printer was used for 3D printing short fiber reinforced nylon filament to study the effects of low-temperature thermal annealing on the 3D printed Ultem 9085 structural properties [ 1 ]. A MarkOne 3D printer (Markforged Company, Watertown, MA, USA) was used for 3D printing continuous carbon fiber Nylon composite specimens [ 2 ].…”