F.J. Alzahrani, H. Noor, J.P. Coulter
Lehigh University,
United States
Keywords: additive manufacturing, BAAM, LSAM, interlayer adhesion, shear stress, shear rate
Summary:
This research investigated the development of Rheo-Printing technology on interlayer adhesion for Big Area Additive Manufacturing (BAAM). Rheo-Printer is an extrusion-based 3D printer equipped with a rotating nozzle for the purpose of controlling melt rheology by tuning the shear rate of the polymer melt. The application of shear rate on shear thinning polymer affects the viscosity of the melt. Many methods have been developed for polymer additive manufacturing (3D printing) building products. Fused Deposition Modeling (FDM) is the most common type of polymer extrusion-based printer and is widely used commercially. FDM uses layer-by-layer building mechanisms to manufacture the products resulting in weak adhesion strength between layers in the building direction (z-axis). This causes mechanical performance variations in printed parts' x, y, and z-axis. Longer layer building time increases heat dissipation, making it more probable that large-scale products may be affected by the weak interlayer adhesion issue. Therefore, this work investigated the development of Rheo-Printing technology on interlayer adhesion strength for BAAM. 2500 HP PLA was used in this investigation to print samples with four different layer-building times 30, 90, 150, and 210 seconds. For each layer-building time, samples were printed with and without using the Rheo-Printing technology. Printed samples were tested in a tensile machine, and results showed that interlayer adhesion strength weakened with increasing layer-building time. However, samples printed with Rheo-Printer had better interlayer adhesion strength.