In this review paper, the authors investigate the state of technology for hybrid- and multi-material (MM) manufacturing of metals utilizing additive manufacturing, in particular powder bed fusion processes. The study consists of three parts, covering the material combinations, the MM deposition devices, and the implications in the process chain. The material analysis is clustered into 2D- and 3D-MM approaches. Based on the reviewed literature, the most utilized material combination is steel-copper, followed by fusing dissimilar steels. Second, the MM deposition devices are categorized into holohedral, nozzle-based as well as masked deposition concepts, and compared in terms of powder deposition rate, resolution, and manufacturing readiness level (MRL). As a third aspect, the implications in the process chain are investigated. Therefore, the design of MM parts and the data preparation for the production process are analyzed. Moreover, aspects for the reuse of powder and finalization of MM parts are discussed. Considering the design of MM parts, there are theoretical approaches, but specific parameter studies or use cases are not present in the literature. Principles for powder separation are identified for exemplary material combinations, but results for further finalization steps of MM parts have not been found. In conclusion, 3D-MM manufacturing has a MRL of 4–5, which indicates that the technology can be produced in a laboratory environment. According to this maturity, several aspects for serial MM parts need to be developed, but the potential of the technology has been demonstrated. Thus, the next important step is to identify lead applications, which benefit from MM manufacturing and hence foster the industrialization of these processes.
Additive Manufacturing (AM) allows the manufacturing of functionally graded materials (FGM). This includes compositional grading, which enables the allocation of desired materials corresponding to local product requirements. An upcoming AM process for the creation of metal-based FGMs is laser-based powder bed fusion (PBF-LB/M) utilized for multi-material manufacturing (MM). Three-dimensional multi-material approaches for PBF-LB/M are stated to have a manufacturing readiness level (MRL) of 4 to 5. In this paper, an advancement of multi-material technology is presented by realizing an industry-relevant complex part as a prototype made by PBF-LB/M. Hence, a multi-material injection nozzle consisting of tool steel and a copper alloy was manufactured in a continuous PBF-LB/M process. Single material regions showed qualities similar to the ones resulting from mono-material processes. A geometrically defined transition zone between the two materials was achieved that showed slightly higher porosity than mono-material regions. Nevertheless, defects such as porosity, cracks, and material cross-contamination were detected and must be overcome in further MM technology development.
Through its unique characteristics, additive manufacturing yields great potential for designing fluid components with increased performance characteristics. These potentials in advanced design, functional structure, and manufacturing are not easily realized. Therefore, the present study proposes a holistic development methodology for fluid components with a specific focus on hydraulic manifolds. The methodology aims to lead the designer from the specification of the task, through a step-by-step embodied design, to a technical and economic evaluation of the optimized, first-time manufactured part. A case study applies the proposed methodology to a part of a rail-vehicle braking application. Through its application, a significant reduction in weight, size, as well as significant contributions to the company’s AM strategy can be assigned to the part. At the same time, increased direct manufacturing costs are identified. Based on the increased performance characteristics of the resulting design and the holistic foundation of the subsequent economic decisions, a satisfying efficiency can be allocated to the proposed methodology.
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