Optimizing PEEK impact strength through multi-objective FDM 3D printing

Abstract

Thermoplastic materials such as Polylactic acid, Acrylonitrile Butadiene Styrene, Polyethylene terephthalate glycol, Nylon, and Thermoplastic polyurethane are favoured in Fused deposition modeling 3D printing due to their cost-effectiveness and versatile properties. However, with the introduction of high grade thermoplastic material poses compatibility challenges with existing machines and processes, impeding widespread adoption in FDM 3D printing. Incorporating new materials into 3D printing requires adjustments to hardware, software, and settings, leading to potential expenses and time investments. Maintaining quality control and consistency becomes complex as each material demands specific parameters and processing conditions. This variability hinders achieving consistent part quality in 3D printing. Moreover, achieving optimal FDM parameters for high-grade polymers (HGPs) like Polyether ether ketone (PEEK) is a challenge due to the distinctive nature of the property, requiring specialized careful considerations during its optimization process. The considerable thermal gradient and heat distribution during printing can lead to residual stresses and deformations, significantly affecting the quality and, in particular, its impact strength. This article optimizes an industry grade 3D printing PEEK based on the limited number of process parameters, namely, build orientation, in-fill density and chamber temperature. Further, the research tries to derive a predictive model for Impact Strength (IS), which is an important consideration for the 3D printed object. In this article, along with the Impact Strength, Printing Time and Material Usage are also studied to find empirical evidence of association between these output variables or response variables. The result indicates that there is a positive significant correlation or association between them. When utilizing a specific parameter setup, the resulting IS of 86.5 kJ/m², a print time of 89 minutes, and a material usage of 3.26 grams are achieved. Notably, there is a measurable reduction of 9.18% in printing time and a 11.66% decrease in material usage when the print density is set to 100% to optimize impact strength. This optimization approach proves the use of composite desirability is a better approach where multiple objectives need to be achieved. The proposed regression model predicts the impact strength with coefficient of determination value more than 50%.