Development of Rapid Tooling Using Fused Deposition Modeling

Abstract

This chapter highlights the in house development of low cost alternative FDM feedstock filament with tailor made properties. The experimental study was performed to fabricate (Nylon6-Al-Al₂O₃ based) alternative fused deposition modeling (FDM) feedstock filament in place of commercial acrylonitrile butadiene styrene (ABS) filament (having specific rheological and mechanical properties) for rapid manufacturing (RM) and rapid tooling (RT) applications. The detailed steps for fabrication of alternative FDM feedstock filament (as per field application) with relatively low manufacturing cost and tailor made properties have been highlighted. The rheological and mechanical suitability of Nylon6-Al-Al₂O₃ feedstock filament has been verified experimentally. The approach is to predict and incorporate essential properties such as flow rate, flexibility, stiffness, and mechanical strength at processing conditions and compared with commercial ABS material. The proportions of various constituents have been varied in order to modify and improve rheological behavior and mechanical properties of alternative FDM feedstock filament. The developed feed stock filament was loaded in commercial FDM setup without any change in hardware and software. The results of study suggest that the newly developed composite material filament has relatively poor mechanical properties but have high thermal stability and wear resistant as compared to ABS filament and hence can be used for tailor made applications.

Finally, the Taguchi experimental log have been designed for investigating the significance of input parameters of screw extruder (such as: mean barrel temperature, die temperature, screw speed, material composition and speed of take up unit) on the diameter deviation of fabricated filaments was analyzed. The tensile strength of alternative feedstock filament has been investigated experimentally according to ASTM-638 standard. The analysis was performed by ANOVA method with the help of MINITAB 17 software. The regression model was developed to realize the influence of input parameters on responses. Tensile strength was significantly affected by the variation of major input parameters during the processing of alternative material on single screw extruder. The ANOVA analysis shows that two process parameters (namely: material composition and die temperature) were significant and remaining two (mean barrel temperature and screw speed) were insignificant. Further a linear regression model has been developed to accurately predict the tensile strength and diameter deviation of alternative feed stock FDM filament. The results highlight that the deviation of <1% was observed in the nine sets of experimental runs, which were compared with predicted values of the regression model. The dynamic mechanical analysis (DMA) result indicates that the filament fabricated with optimum combination of parameters have highest stiffness and more suitable for FDM system. The process capability study suggest that, with optimum combination of single screw extruder parameters, the process lies within the spread of ±4σ having C_p and C_pk value 1.43 and 1.354 respectively. The cost effective solution investigated in this research work may help in enhancing the application of FDM process for various industrial applications.