## 3 Additive Manufacturing of Pla-Metal Biodegradable Composites
According to the findings, a distinct fracture mechanism occurs when printing horizontally rather than vertically, resulting in stronger components for the material under investigation. More infill density and an ordered fill pattern both contribute to increased mechanical strength [72]. Four key parameters related to FDM were primarily examined: layer thickness, infill density, nozzle temperature, and manufacturing speed. Generated for the FDM method was a 14 wt. % nano copper reinforcement with PLA. The prepared filament was constructed according to ASTM standards and subjected to various parametric conditions to learn about the mechanical characteristics exhibited by the composite filament and the impact of FDM parameters [73]. Experimenters investigated and reported the influence of layer height, bed temperature, and nozzle temperature on compression and flexural behavior of the 3D printed samples. A rise in both compressive and flexural strengths has resulted from the heated bed and nozzle [74]. In various experimental studies, PLA-bronze filaments were used for the manufacturing of 3D printed composites. The test pieces were produced using the commercial 3D printer WANHAO Duplicator 6 with a nozzle diameter of 0.4 mm in the additive manufacturing laboratory at Szent Istvan University, Hungary. The specimens were printed with a 45\({}^{\circ}\)/135\({}^{\circ}\) raster angle. The printing temperature and platform temperature were maintained at 195 \({}^{\circ}\)C and 60 \({}^{\circ}\)C, respectively. Before testing, the specimens were conditioned in a climate room with a temperature of 25 \({}^{\circ}\)C and relative humidity of 50% [75]. For obtaining intact 3D printed composites using PLA-brass filaments, examiners meticulously manipulated printing parameters, such as layer height and printing speed, on a Raise3D N2 Plus FDM 3D printer to produce test specimens with varied compositions. Layer height values span 0.25 mm, 0.30 mm, and 0.35 mm, and the printing process speedsrange from 20 mm/s to 40 mm/s. The compositional variables range from 15 to 80 wt. %. Find out how the printing parameters affect different mechanical characteristics with the help of this research. For instance, it was noted that the optimal printing parameters for achieving the highest elastic modulus in tensile testing were a layer height of 0.25 mm and a manufacturing speed of 30 mm/s [76]. Similarly, the study clarifies how to modify additive manufacturing parameters to enhance the properties of PLA/brass composite materials for diverse applications. In addition to expanding the research understanding of PLA/brass composites, an opportunity to develop novel materials was also explored [77]. Research works focused on the manufacturing of 3D-printed composites using PLA-titanium filaments with varying process parameters such as nozzle temperature, layer height, infill density, and bed temperature. The analysis of variance (ANOVA) showed that the following factors significantly affected the tensile test results: nozzle temperature (19.9%), layer height (1.9%), bed temperature (39.5%), and infill density (28.5%), listed from most to least important. A combination of a 224 \({}^{\circ}\)C nozzle temperature, 0.2 mm layer height, 41 \({}^{\circ}\)C bed temperature, and 95% infill density produced the maximum tensile stress of 15.4 MPa [57]. For printing PLA/aluminum, the following three control input parameters were provided: the number of shells, infill density, and layer thickness. There were three possible values for the following parameters: layer thickness (0.1, 0.2, and 0.3 mm), number of shells (2, 3, and 4), and infill density (20%, 40%, and 60%) [78]. To produce the PLA/Iron (Fe) and PLA/stainless steel (SS) composites, the printing parameters include an infill density of 100%, printing rates ranging from 30 to 90 mm/s, and temperatures between 260 and 290 \({}^{\circ}\)C [79].