Initial situation

Additive manufacturing (AM) has established itself in recent years as a forward-looking technology for the integral production of functionally integrated components. In particular, powder bed fusion with laser beam offers a high degree of geometric design freedom due to its layer-by-layer manufacturing process, enabling the fabrication of complex, customized structures with excellent dimensional accuracy. However, the technology reaches its limits when components exceed the available build volume. Integral design approaches can become disadvantageous or unfeasible, especially in cases where localized wear necessitates the replacement of an entire AM component instead of the damaged areas only. In such cases, a fully integrated design proves to be impractical or even disadvantageous – for example, in terms of maintenance requirements or the use of different materials.

Against this background, differential design is gaining relevance. Here, the component is subdivided into functionally adapted segments that are manufactured separately and subsequently joined. This segmentation not only enables the orientation of individual parts according to functional and manufacturing requirements but also reduces the need for support structures and allows targeted adaptation to anisotropic properties. The successful implementation of such an approach, however, requires the development of suitable evaluation and design methods to systematically and reliably manage the processes of partitioning and joining.

Project objectives

The aim of this research project is to unlock the potential of AM for large-scale components by applying differential design principles and combining them with appropriate joining techniques. This approach seeks to overcome build volume limitations and enable components to be adapted more precisely to their intended function. Central to this goal is the development of a methodology for performance- and manufacturing-oriented segmentation of large components, followed by joining according to specific requirements. The partitioning process is guided by functional, mechanical, and manufacturing constraints, with particular attention given to anisotropy effects and spatial positioning within the build chamber.

To ensure the structural integrity of the resulting assemblies, various joining techniques are analyzed, with a particular focus on thread-forming screws as a representative example of mechanical joining in AM. AM enables innovative designs of the joining zones, such as customized bore geometries that enhance load distribution. The influence of the joining method on the structural performance is systematically investigated, especially regarding mechanical stresses and manufacturing tolerances.

Another core objective of the project is the structured, machine-readable documentation of all relevant findings in a digital database. This forms the foundation for a computer-aided evaluation and decision-support tool. In addition, a graph-based system is being prototypically developed and tested. This system allows for the context-sensitive analysis of requirements, influencing factors, and functional interdependencies, thereby enabling the identification of appropriate partitioning and joining strategies.

Procedure

The project is organized into several interconnected work packages (WP). In the initial phase, the key factors influencing partitioning decisions in AM components are identified and analyzed. These include build orientation, support structure requirements, anisotropic material behavior, and functional constraints. The interactions among these parameters are modeled to derive a method for evaluating suitable separation areas (WP1).

Subsequently, various joining technologies are assessed for their applicability in reconnecting additively manufactured component segments (WP2). Special emphasis is placed on thread-forming screws. Strategies are developed to optimize borehole geometry for both manufacturability and mechanical performance. Integration of the joining zones into the overall component design is performed regarding accessibility, wall thickness, and load paths. The resulting design principles are validated through experimental testing (WP3).

To consolidate the findings, a digital database is created, capturing both manufacturing and functional aspects of partitioning and joining (WP4). This database serves as the basis for a prototypical graph-based framework (WP5), in which all relevant influencing factors are represented as nodes, and their interactions as edges. The resulting system provides a practical, application-oriented decision-support tool for designers working in AM environments.