Directed energy deposition (DED) additive manufacturing technology enhances the functionality of existing or damaged parts by adding metallic materials to the surfaces. Blown-powder DED technology utilizes a focused, high-energy source to fuse the part’s surface with the supplied metal powder. Maintaining a constant stand-off distance (SOD), the distance between the deposition head and the workpiece, is a key factor in ensuring deposition quality, as variations in SOD will change the powder focus position and the laser spot size on the surface. Therefore, traditional additive manufacturing systems require CAD or pre-scanned surface data. In this study, we proposed auto-surface tracking technology. No workpiece CAD data or pre-scanned surface data are required, and in-situ measurement and feedback control can automatically consider the deposition height differences that cause a change in SOD when depositing the next layer. The accuracy of the SOD measurements and feedback control error was verified using a step height sample. The mean SOD measurement error was 4.7 ㎛ with a standard deviation of 42 ㎛ (reference SOD, 14 ㎜). The feasibility of the autosurface tracking technology was confirmed through the additive manufacturing processes of the gear and an actual blanking mold applied in the defense and industrial fields.

In this study, design for additive manufacturing (DfAM) of release agent injection manifold for hot forging has been performed to achieve weight reduction and flow path optimization. The weight reduction of 53.5% was achieved, thereby enabling the application of stainless steel 316L, which has high strength and corrosion resistance. Lightweight manifolds using Al-Mg-10Si and SUS316L materials were fabricated by PBF-type metal 3D printer. The feasibility test showed that mold life was improved by 14% by solving residual release agent problem. In addition, the flow path optimization results suggested that the flow standard deviation of each outlet dropped sharply from 264 to 75 ㎤/s. This approach demonstrated that DfAM for release agent manifold could be applied to increase mold life and improve product quality and productivity for hot forging.

Owing to recent advances in additive manufacturing technology, design for additive manufacturing (DfAM) has been used to overcome design limitations due to constraints in traditional manufacturing processes. In this study, we applied DfAM technology to design lightweight and consolidated vacuum grippers for inspection equipment. We proposed a consolidated design to reduce manufacturing time and costs, which previously encompassed assembling eleven components. Topology optimization was used to reduce part weight while maintaining structural rigidity and safety, and two optimization models were designed: two-piece and one-piece models. Based on these optimized geometries, the internal vacuum paths were designed in a curved shape to enhance adsorption characteristics. Numerical simulations were conducted to evaluate the structural performance and flow characteristics of the initial design and the two optimization models. The pressure drop of the one-piece model, which was the best design, was reduced to 1/8 of the initial design and the structural safety factor was predicted to be 6.37. This final design was then additively manufactured by a digital light processing type 3D printer and the weight of the resulting parts was reduced from 12.94 to 2.08 g. Experimental observation found that the additively manufactured vacuum gripper showed enhanced absorption performance compared to the initial design.