## 4 Discussion
The focus of the proposed work is not the analysis of the deformations themselves but rather the comparison of the two LMD machines in terms of geometrical accuracy. Consequently, it was convenient to keep the components attached to their substrate during acquisition, which was also advantageous for the scan alignment procedure. According to Figures 13-15, the component is progressively contracting, moving from the bottom to the top, and it is bending toward its center axis. The presence of the bulk substrate, which absorbs residual stresses, causes less deformation at the base of the component. As previously explained in relation to Figure 12, the influence of the substrate decreases as the layers ascend. This corresponds to the visible bending of the component. The geometrical distortion is so significant that the outer surface of the deposited part overlaps with one of the CADs at the top of the component: there is no machining allowance here, and the stock material on the inner surface is excessive. Residual stresses are always present in the DED LB process and distort the component during deposition. Heat treatments on the component can relieve residual tensions. However, after being removed from the substrate and heat treatments are applied, the final output will not match the planned CAD file. A common practice is to deposit and treat the component once, then measure the distortions with a 3D scan and create a new CAD file correcting for the component deformations, expanding it where it is shrunk, and downsizing it where it is larger. Another method for predicting deformations is to do simulations of the heat cycles of the deposition [32; 33]. The comparison of the two deposited components confirms that there are no major differences when analyzing the capability of the two machines of accurately depositing the chosen component. The deformation behavior of the two realized parts does match. The component realized in the articulated robot-based LMD machine has only a small overgrowth. However, because of the self-regulation phenomenon typical of the process, overgrowth concerns are reduced and do not propagate during the builds [34]. Further to that, the component produced by the gantry-based machine is rougher on its inner wall in some positions than the component produced by the articulated robot-based machine: there is material accumulation in the central region of sector B, where the slope of the wall varies between 30 deg and 9 deg. The increased roughness is caused by sintered material on the side of the component. This imperfection can be removed using surface cleaning procedures or by machining when the allowance is removed. These two considerations indicate that, even though the machines are remarkably similar in many ways (laser source, optics, and powder delivery system) and the deposited single tracks are equivalent, the machines perform slightly differently. However, these two aspects (overgrowth of the component realized with the articulated robot-based system and sintered material on the inner side of the component realized with the gantry-based system) cannot be attributed to the kinematics of the two machines but are most likely related to minor differences in the laser source, optics, and powder delivery systems, or to different wear states of them. As a result, when only the actual deformation state of the two components is considered, there are no significant disparities that can be attributed to the two different kinematics of the two machines, indicating that increased accuracy of CNC machines is not required when dealing with LMD of large axisymmetric components.