3D printing is widely used for various applications as it offers many benefits. The mechanical property of the part manufactured by using 3D printing is very critical. For that reason, it is important to understand how different values of 3D printing process parameters impact the mechanical properties of the part. As Polylactic Acid (PLA) is most widely used as 3D printing material, it is chosen as the material discussed in this research. The purpose of this research is to provide information related to the influence of various parameters of 3D printing to the mechanical properties of the PLA part. A literature review was performed based on the current research that investigates the 3D printing process of PLA. Based on the literature review, the infill design parameters are considered as important parameters and discussed in this research. The infill design parameters referred in this research are layer thickness, infill pattern, infill density, infill width, and infill deposition speed. The mechanical properties discussed in this research are tensile strength and yield strength, ductility, elasticity or young modulus, compression strength, flexural strength, and stiffness.

Previous researchers tried to improve the mechanical properties of 3D printed part by adding short or continuous, natural, or nonnatural fibers as the reinforcement for thermosetting or thermoplastic matrix. None of the research found in the literature incorporates continuous natural pineapple leaf fiber as the reinforcement for polylactic acid (PLA) matrix by using 3D printing. The objective of this research is to investigate the tensile strength, the elongation, and the dimensional error of the 3D printed parts made of continuous pineapple leaf fiber-reinforced PLA composite using different values of extrusion temperature and feed rate. The experiment involves 32 factorial design with two replications and, therefore, prints 18 tensile test specimens according to ASTM D638. Based on the result of the experiment, it can be concluded that the use of continuous pineapple leaf fiber as the reinforcement for the PLA matrix increases the tensile strength of the composite. The use of continuous pineapple leaf fiber does not increase the dimensional error value of the composite part beyond the maximum value of the common fused deposition modeling printed part. Moreover, the required time to print the composite part is the same as the required time to print the pure PLA part. However, the elongation of the composite part is lower than the pure PLA part.

<p class="Abstract">To optimize the 3D printing process, the influence of its parameters on the performance of the printing process needs to be investigated. This research investigates the effect of infill pattern, infill density, and infill angle on the printing time and the filament material length. First, this research collected the printing time and the filament length data for each combination of infill pattern, infill density, and infill angle. The data collection was conducted by implementing Repetier-Host v.2.1.6 software as a data acquisition tool. Then, the General Linear Model was applied to analyze the effect of infill pattern, infill density, and infill angle on the printing time and filament length. Based on the analysis, higher infill density increases the printing time for each infill pattern and each infill angle. Also, higher infill density increases the filament length for each infill pattern and each infill angle. The implementation of the Gyroid type of infill pattern reduces the required printing time for each density. Meanwhile, the implementation of the 3D honeycomb type of infill pattern increases the filament length for each infill angle. The use of the 45° infill angle increases the filament length and printing time. To reduce the filament length and printing time, the 90° infill angle should be implemented.</p>

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Rapid prototyping is fast and automatic three dimensions physical modeling that uses computer aided design model as the input. One of the important requirements in various products is the surface quality. Therefore, the aim of this research is to study and then develop a model that shows the influence of depth of cut, feed rate, and step-over on the vertical and horizontal surface roughness of polycarbonate material in subtractive rapid prototyping. The subtractive rapid prototyping process is performed by using Roland MDX 40 machine assisted by CAM Modela Player 4.0 software. This research implements response surface methodology to develop the model and then followed by the residual tests. The result shows that the increase of the depth of cut and the interaction between the step-over and the depth of cut will increase the horizontal surface roughness. Meanwhile, the vertical surface roughness will be affected mostly by the step-over. This research provides an insight on how to rapid prototype the polycarbonate material in order to achieve the surface requirement. The result of this research is the basis for achieving the main purpose of subtractive rapid prototyping which are maximum material rate removal and the minimum surface roughness.