## 4 Results and Discussion  
In producing components using layer-by-layer methods, the uniformity of the created layers plays a crucial role in determining the precision of the final piece. Any deviation from uniformity can result in distortion or dimensional changes in the component. Therefore, this study investigates the uniformity of weld bead height, employing the effective parameters of the GMAW process. The research explores the impacts of welding voltage, wire feed speed, nozzle travel speed, and nozzle angle, considering three levels for each parameter through a factorial experimental design. Subsequently, the smoothness of the weld bead top line is analyzed using image processing and wavelet transform techniques. The aim is to identify the optimal parameters that yield a desirable smoothness in the weld bead top line for producing components using additive manufacturing via arc welding with shielding gas. To attain a uniform height for the weld bead line as per the experimental design, 81 experiments were conducted. Figure 12 shows the weld beads according to the experimental design. Figure 11: The process of producing a 3D piece. Figure 12: Weld beads according to the experimental design. Following this, the algorithm described in the second part of this article was used in connection with image processing to extract the lines indicating the uniformity of the height of the weld bead. The algorithm described in the third section of this article was employed in conjunction with image processing to extract the lines representing the weld bead's height uniformity. Figure 13 illustrates the stages from the weld bead image to the top-line image. Given that the objective is to obtain an image of the top edge of the weld for uniformity assessment, the camera angle and the specific line selected as the weld bead top line are not of paramount importance; only the parameter of line smoothness is under consideration. Following the extraction of weld line coordinates using image processing techniques, the weld line is transformed into a one-dimensional waveform through one-dimensional wavelet transform, decomposing it into details and approximations. Utilizing these details allows for distinguishing between a smooth and non-smooth weld bead. Based on the results obtained from image processing and wavelet transform, the smoothest weld bead, or, in other words, the weld with the most uniform height, is selected for the production of components. To evaluate the effectiveness of the proposed method, a specific geometric component, in this case a turbine blade geometry, was chosen. This particular component featured complex geometry, necessitating the fabrication of a three -axis CNC table. The precision table enabled movements with an accuracy of 0.05 units in the z, y, and x directions, facilitating the manufacturing process. The selected model consisted of multiple layers, making it suitable for assessing the performance of the proposed method. Based on the weld bead height, it was determined that 63 layers were needed to construct the component. A Lisp-based program within the AutoCAD software environment generated the required motion codes for creating each layer. It should be noted that the thickness between the layers was obtained by creating a wall of the best welding beads according to the experiments. Figure 13: Welding bead image processing steps: (**a**) Base image. (**b**) Appling filters. (**c**) Increase image contrast. (**d**) Edge sharpening. (**e**) Image binarization. (**f**) Using imdilate function and stretch image in 45\({}^{\circ}\) direction. (**g**) Filling image holes. (**h**) Detect upper line. Welding was conducted according to specific parameters, including a voltage of 27 V, a wire travel speed of 252 cm/min, a nozzle angle of 90 degrees, and a nozzle travel speed of 315 mm per minute, based on the results of the conducted experiments. These parameters yielded the smoothest weld bead line.