Investigating The Role of Printing Bed Temperature On the Mechanical Properties and Microstructure of FDM Printed Parts

Abstract

Fused Deposition Modelling (FDM) based 3D printing has come a long way in the last few decades. Process parameter modifications, printer design, and operations needs improvements for it have diverse biomedical application. This study investigates the effect of printing bed temperature on the mechanical properties and microstructures of 3D-printed Poly Lactic acid (PLA) films. PLA is one of the most commonly used polymers for building models for medical devices, implants, microfluidic devices, and micro devices for various biomedical applications. Microstructures and designs are of utmost importance for the device’s functionality. We hypothesize that increase in the number of layers during printing lead to differential cooling rate at each layer as the effect of bed temperature decrease with increasing layer height. This will result in microstructural defect in each layer of the printed sample. PLA films ranging from 1.0 mm to 4.0 mm thickness, grid-type infill pattern were printed at bed temperatures (60oC - 90oC). Other printing parameters like infill percentage, raster angle and nozzle temperature were kept constant throughout the experiment. The microstructures of different specimens were visualised and characterised using an optical microscope. Further, we evaluated the mechanical properties of the samples using an Ultimate Testing Machine at a 2mm/sec strain rate. FE-SEM images of the mechanically fractured area showed microvoids in the printed filament whose number decreases with the bed temperature. We observed that there is no effect of bed temperature on the mechanical properties of 3D printed samples but the number and distribution of microvoids increases with decrease in bed temperature. Thus, this study has provided insights into the optimal printing conditions with optimal mechanical properties with minimal microdefects, which is a promising step towards developing better 3D printed devices.