Material Extrusion of Structural Polymer–Aluminum Joints—Examining Shear Strength, Wetting, Polymer Melt Rheology and Aging

Abstract

Generating polymer–metal structures by means of additive manufacturing offers huge potential for customized, sustainable and lightweight solutions. However, challenges exist, primarily with regard to reliability and reproducibility of the additively generated joints. In this study, the polymers ABS, PETG and PLA, which are common in material extrusion, were joined to grit-blasted aluminum substrates. Temperature dependence of polymer melt rheology, wetting and tensile single-lap-shear strength were examined in order to obtain appropriate thermal processing conditions. Joints with high adhesive strength in the fresh state were aged for up to 100 days in two different moderate environments. For the given conditions, PETG was most suitable for generating structural joints. Contrary to PETG, ABS–aluminum joints in the fresh state as well as PLA–aluminum joints in the aged state did not meet the demands of a structural joint. For the considered polymers and processing conditions, this study implies that the suitability of a polymer and a thermal processing condition to form a polymer–aluminum joint by material extrusion can be evaluated based on the polymer’s rheological properties. Moreover, wetting experiments improved estimation of the resulting tensile single-lap-shear strength.

Influence of post-processing on the adhesion of dual-species biofilm on polylactic acid obtained by additive manufacturing

“…The evaluation of material behavior over time is relevant to assess the relative durability, time of applicability and use in various medical applications without compromising the patient or the functionality of the designed prosthetic component ( Barrasa et al, 2021 , Bechtel et al, 2022 , Bergaliyeva et al, 2022 ). It can be performed by the thermal aging technique, which consists of the complete immersion of the sample in water at a given temperature and time, to simulate the use term ( Barrasa et al, 2021 , Bechtel et al, 2022 , Bergaliyeva et al, 2022 ).…”

“…The evaluation of material behavior over time is relevant to assess the relative durability, time of applicability and use in various medical applications without compromising the patient or the functionality of the designed prosthetic component ( Barrasa et al, 2021 , Bechtel et al, 2022 , Bergaliyeva et al, 2022 ). It can be performed by the thermal aging technique, which consists of the complete immersion of the sample in water at a given temperature and time, to simulate the use term ( Barrasa et al, 2021 , Bechtel et al, 2022 , Bergaliyeva et al, 2022 ). The rough, porous surface and the biodegradability of PLA, accelerate aging leading to reduced mechanical performance and altered surface, which may favor the growth of microbial adhesion ( Barrasa et al, 2021 , Bechtel et al, 2022 , Bergaliyeva et al, 2022 , Fernández-Grajera et al, 2022 ).…”

“…It can be performed by the thermal aging technique, which consists of the complete immersion of the sample in water at a given temperature and time, to simulate the use term ( Barrasa et al, 2021 , Bechtel et al, 2022 , Bergaliyeva et al, 2022 ). The rough, porous surface and the biodegradability of PLA, accelerate aging leading to reduced mechanical performance and altered surface, which may favor the growth of microbial adhesion ( Barrasa et al, 2021 , Bechtel et al, 2022 , Bergaliyeva et al, 2022 , Fernández-Grajera et al, 2022 ).…”

Manufacturing of Metal–Polymer Hybrid Parts Using a Desktop 3-Axis Fused Filament Fabrication 3D-Printer

“…The schematics of the AddJoining approach is presented in Figure 1. To date, the AddJoining technique (whether named as such or not) has been studied at the coupon level with several material combinations and from different perspectives [2][3][4][5][6][7][8][9][10][11][12]. While several different approaches have been utilized to improve metal-polymer joint strength, little to no attention has been devoted to the manufacturing of larger and more complex parts using the proposed technique.…”

“…While more-recent 5-axis setups can be considered more advanced technologically and therefore more capable of addressing the aforementioned challenges, they are also considerably more expensive and much less user-friendly, both in terms of slicing algorithms, toolpath generation and machine tailoring/modification. Therefore, to preserve aspects that have made desktop 3D-printers extremely popular while still being able to manufacture 3D models over large and/or complex (i.e., nonflat) substrate geometries, it is necessary to introduce printing strategies that can work To date, the AddJoining technique (whether named as such or not) has been studied at the coupon level with several material combinations and from different perspectives [2][3][4][5][6][7][8][9][10][11][12]. While several different approaches have been utilized to improve metal-polymer joint strength, little to no attention has been devoted to the manufacturing of larger and more complex parts using the proposed technique.…”