Development of Functionally Graded Material Through the Fused Deposition Modeling-Assisted Investment Casting Process: A Case Study

Abstract

Aluminum matrix composites (AMCs) are one of the most demanding engineering materials in the category of metal matrix composites (MMCs) due to their light weight and excellent mechanical and tribological properties. The main objective of the present research work was to develop Al–Al2O3 composites through the fused deposition modelling-assisted investment casting (FDMAIC) process by using reinforced fused deposition modeling (FDM) feedstock filament as a novel method. Initially, experimentation was performed using the melt flow indexer (MFIer) to select the appropriate proportions of nylon-6, Al powder, and Al2O3 powder for obtaining the same melt flow index (MFI) as the commercial Acrylonitrile-Butadiene-Styrene (ABS) has. During the second stage, the fabricated FDM filaments were used for the manufacturing of investment casting sacrificial patterns on the existing FDM system. Barrel finishing (BF) was used to improve the surface finish of the sacrificial patterns prior to ceramic molding. Taguchi L18 orthogonal array was used for designing the control log of experimentation, and the signal-to-noise (S/N) ratio has been analyzed to determine the effect of input process parameters (such as filament proportion, volume of FDM pattern, density of FDM pattern, BF cycle time, BF media weight, and number of slurry layers) of the properties (such as surface roughness, dimensional accuracy, hardness, and wear) of the castings developed. Characterization of the castings was performed by using an optical microscope, scanning electron microscopy, energy dispersive spectrometry, and X-ray diffraction analysis. It has been found that the distribution of Al2O3 particles was limited to the outer surface of the castings and the core was not reinforced; therefore, the composites developed can be considered functionally graded material (FDM). The castings developed were found to be acceptable as UNI-EN-20286-i (1995), and the process was statistically controlled for batch production.