# Optimization Parameters for PLA Through Additive Manufacturing: Taking Mixed Shapes as an Example
## 1 Introduction  
Additive manufacturing, with its unique competitiveness, has advantages such as achieving manufacturing efficiency, producing complex structures, and reducing material waste, which have be challenges in traditional methods. It finds applications in various fields including automobiles, aerospace, medical appliances, and cultural and creative jewelry. Poor mechanical properties of products often occur in the additive manufacturing process. This leads to the breakage of mechanisms during assembly or actuation. Therefore, obtaining the best quality end products is very important.  
In this study, the literature was collected first, and then the fishbone diagram was used to list the processing parameters affecting that affect the quality of the print. Based on the factor of nozzle gap height, extruder temperature, bed temperature, infill print head velocity, retraction velocity, Infill pattern, and fill spacing. Design parameter combinations in orthogonal table L16(45), 3D printing and analysis of the optimal parameters with the Taguchi method and the Response surface methodology. Its dimensional accuracy is optimal parameters: nozzle gap height 0.1 mm, extruder temperature 185 \({}^{\circ}\)C, bed temperature 75 \({}^{\circ}\)C, infill print head velocity 35 mm/s, retraction velocity 65 mm/s; and ultimate strength are nozzle gap height 0.1 mm, filling spacing 0.6 mm, Infill pattern triangular, infill print head velocity 35 mm/s, extruder temperature 220 \({}^{\circ}\)C. Finally, the dimensional accuracy is increased by 22.54%, and the ultimate strength is increased by 5.731 MPa. From the research results, the relationship between the factors of additive manufacturing, and it is expected that this research will contribute to the users of additive manufacturing.  
The material extrusion technology is greatly affected by machine parameters, so the parameters must be selected correctly to enhance the quality characteristics [1]. Many parameters/factors in the additive manufacturing process influence products' mechanical properties. Among these parameters/factors, nozzle gap height, fill spacing, infill print head velocity, and extruder temperature have a greater influence [2, 3, 4, 5, 6, 7, 8, 9, 10]. The influence of additive manufacturing processing parameters on the end products' end properties isdiscussed using the Taguchi method to analyze the optimal combination of processing parameters [11; 12; 13]. Using Tensile testing, all results from defect observation, microstructural and mechanical properties confirmed the potential for WAAM process reuse [14; 15; 16; 17; 18].  
Based on the aforementioned literature, research has only focused on individual outcomes. Compared to Refs. [1; 2; 5], they only study the mechanical properties of 3D printed products. Nowadays, the applications of 3D printing are extensive, so the dimensional accuracy of the finished products is certainly important. Therefore, this study investigates two experimental objectives: dimensional accuracy and Tensile strength, in order to obtain the optimal set of printing process parameters.