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Fused deposition modelling (FDM) is a technique of additive manufacturing used to fabricate a 3D (three-dimensional) model with layer-by-layer deposition of required materials with less material wastage. FDM is used to make any objects with a meager cost, but also there are some negative points related to less strength, less accuracy, and less surface finish. In this study, acrylonitrile butadiene styrene (ABS) is printed using an FDM printer to investigate the effects of various changing parameters like nozzle temperature (°C), infill pattern, and printing speed (mm/s) on surface roughness and thickness measurement. Experiments are designed using the Taguchi L9 orthogonal array method and ANOVA method. For obtaining an increase in surface roughness, the most influencing factor is printing speed with 83.41% contribution, and the effect of nozzle temperature is 9.04%. Lesser printing speed enhances the surface finish and, in the case of thickness and outer dimension of all the printed samples, results are almost constant. Regression analysis is performed to formulate the single-objective equations, and a genetic algorithm (GA) is applied to optimize the values of process parameters.

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The quality of 3D printed thermoplastic structures mainly depends upon the various aspects of deposition pattern, processing conditions, and layer bonding. The incomplete layer-to-layer adhesion during the additive manufacturing process is the most critical issue since thermoplastics are bad heat conductors. In this study, aluminum (Al) microfilms have been deposited to promote the adhesion between the additive layers. The composite structures (as per ASTM D 695) of polylactic acid thermoplastic were manufactured by fused filament fabrication (FFF) process and consecutively reinforced with Al spray. The composite structures were subjected to compressive loading to investigate the influence of input process variables like; in-between microfilm layers (1-5 layers), bed temperature (60-100 °C), and infill percentage (40-100%). The results of the study suggested that using microfilm in-between additive layers is a promising technique for improving the compressive properties. The compressive strength has been observed maximum by performing FFF with 3 layers of Al microfilm, 70% of infill percentage, and 100 °C bed temperature. The results are supported by scanning electron microscopy, energydispersive spectroscopy, and differential scanning calorimeter analysis. An optimization study was successfully conducted using the analytic hierarchy process, which predicted the optimum parameter settings based on the relative importance of each response variable.

The fusion of additive layers is the primary concern, which affects the mechanical properties of the three-dimensional printed structures prepared by material extrusion-based additive manufacturing (MEAM) process. To promote the fusion and strength between the thermoplastic layers during MEAM process, the metal spray in between the additive layers is used as a novel approach. In this study, aluminium (Al) spray has been deposited in between the polylactic acid structures to enhance the bonding of the additive layers. The methodology includes deposition of 1, 3 and 5 Al spray layers at periodic time intervals with varying infill percentage (40%, 70% and 100%) and bed temperature (60°C, 80°C and 100°C). The structures have been subjected to flexural testing for investigation of the role of each input process parameter followed by fracture morphology analysis through scanning electron microscopy and energy-dispersive spectroscopy. The results of the study suggested that the maximum flexural strength is possible with five spray layers, 70% infill and 100°C bed temperature.