Process optimization of single screw extruder for development of Nylon 6-Al-Al2O3 alternative FDM filament

Abstract

Purpose The purpose of this study is to investigate the process parameters of a single-screw extruder for development of Nylon6-Al-Al2O3-based alternative fused deposition modeling process (FDM) feedstock filament (in lieu of commercial acrylonitrile butadiene styrene filament). The effect of major screw extruder parameters on the tensile strength of fabricated filaments has also been analyzed. Design/methodology/approach The Taguchi experimental log has been designed for investigating the significance of input parameters of screw extruders (such as mean barrel temperature, die temperature, screw speed, material composition and speed of take up unit) on the tensile strength of fabricated filaments. The suitability of alternative material as an FDM filament has been verified by rheological investigations. The tensile strength of an alternative feedstock filament has been investigated experimentally according to the ASTM-638 standard. The analysis was performed by the analysis of variance (ANOVA) method with the help of MINITAB 17 software. The stiffness of the FDM printed parts with nine different feedstock filaments (prepared by selecting nine different combinations of analytical parameters) was determined by dynamic mechanical analysis (DMA). Findings The tensile strength of the feedstock filament was significantly affected by the variation of major input parameters during the processing of alternative material on a single-screw extruder. The ANOVA shows that two process parameters (namely, material composition and die temperature) were significant at the 5 per cent level (“F” value 41 and 21.96, respectively) and remaining two (mean barrel temperature and screw speed) were insignificant at the 5 per cent level. Further, a linear regression model has been developed to predict the tensile strength of the alternative feedstock FDM filament. The results highlight that a deviation of <1 per cent was observed (in the tensile strength of nine sets of experimental runs) as compared to the predicted values of the regression model. In addition to above, the DMA result also indicates that the filament fabricated with optimum combination of parameters has highest stiffness and is more suitable for the FDM system. Research limitations/implications During the processing of alternative material in a single-screw extruder and FDM system, the increase of filler contents adversely affects the contact surfaces. Practical implications The FDM parts with customized properties (viz., thermal and tribological) can be fabricated with alternative feedstock filament material. Originality/value The potential to consider alternative filament material for FDM system includes rapid manufacturing of functional parts, tailor-made grinding tools for dentists and rapid tooling of metal matrix composites having complex geometry.