This study investigates the challenges of additively manufactured interlocking structures, emphasizing joinability issues due to thermal deformation. These challenges become pronounced when fabricating high-density structures without fully interconnected layers, a trait common in soft magnetic materials. Here, a detailed analysis assessing deformation concerning pin thickness and build orientation in a representative interlocking model is performed. Utilizing stress and thermal simulations of the additive manufacturing process, it is shown that a compensated design considerably enhances the joinability of these structures. These findings offer valuable perspectives for advancing the design of additive manufacturing components, particularly in soft magnetic materials such as electric motor stators, which require both insulation and density.

With the increasing demand for high-performance leisure boat propellers, this study explores the development of high-strength aluminum alloy propellers using the low-pressure die-casting (LPDC) process. In Part I of the study, we identified the optimal alloy compositions for Al-6Zn-2Mg-1.5Cu propellers and highlighted the challenges of hot tearing at the junction between the hub and blades. In this continuation, we developed a coupled thermal fluid stress analysis model using ProCAST software to optimize the LPDC process. By adjusting casting parameters such as the melt supply temperature, initial mold temperature, and curvature radius between the hub and blades, we minimized hot tearing and other casting defects. The results were validated through simulations and practical applications, showing significant improvements in the quality and structural integrity of the propellers. Non-destructive testing using X-ray CT confirmed the reduction in internal defects, demonstrating the effectiveness of the simulation-based approach for alloy design and process optimization.

Additive manufactured interlocking structures often face challenges in achieving suitable joinability due to thermal deformation. This issue becomes particularly interesting when fabricating structures that require high density but not fully connected layers, such as soft-magnetic materials. This study focuses on systematical investigation of the deformation as a function of finger thickness and building direction in model interlocking structure. In the perpendicular direction to the build plate, the distortions of joint part were significantly reduced due to lower thermal stress. In addition, the effect of laser power and scan speed on interlocking structure are systematically discussed. Additionally, through stress and thermal simulations of additive manufacturing process, it was confirmed that the compensated model can enhance the joinability of interlocking structures. These findings contribute to the development of optimal design for additive manufactured parts of soft magnetic materials such as stators in electric motor components, which needs insulations and density.

Cold rolled steel sheets are produced as relatively thin sheets with a thickness of 0.2mm to 2.0mm, and are manufactured through hot-rolled steel pickling, cold rolling, and heat treatment. In addition, cold rolled steel sheets generally have beautiful surfaces, and are widely used as exterior and interior materials for automobiles, home appliances, and building materials. However, cold rolled steel sheets, which are hot-rolled to a thickness of 2mm or less at room temperature, are the most difficult to manufacture among all steel products and require high-level technology. In any case, the final product of cold rolled steel sheets is first produced in sheet form, and since the length of this sheet reaches several kilometres, the ends of the sheets are usually welded together and shipped in coil form. However, due to the tension applied to this coil, the welded part often breaks, causing accidents that stop the production line. The problem at this time is that such production line stoppages act as a factor in increasing production costs, so it is important to monitor such defective conditions in advance and prevent accidents. Our customers are also well aware of these problems and are interested in developing cost-effective methods to solve them. In this paper, we tested whether we can solve this problem in real time by processing artificial defects on the test specimens provided by our customers. The experimental results have yielded some positive results and we are preparing to try to commercialize it by linking it to an actual production line. Through this presentation, we would like to discuss the problems that we could not anticipate and collect opinions related to the development of the system.