## 2 Methodology--Related Works
### Factory Planning  
The factory planning process involves a structured and multi-step approach, utilizing various tools and methods to design and dimension manufacturing systems [1; 2; 31; 32; 33]. The process of planning a factory is subject to constant improvement. The reason for this is the constant evolution and increase in computing power, cloud computing, and other technological advancements. Three-dimensional scanning, BIM (Building Information Management), or augmented and virtual reality can be named in this context. Even though the tools and methodologies are subject to constant innovation, the fundamental planning process is still the same. It can be categorized into distinct successive phases. Each phase focuses on different aspects and levels of detail. Figure 3 offers a cross-section of a number of factory planning guidelines. The various phases and their content, as outlined by the respective authors, are displayed [1; 34; 35; 36; 37; 38; 39]. Figure 3: Overview of the phases of different planning methodologies (excerpt) [40]. According to most guidelines, the planning process begins with Phase I. This phase entails defining project objectives and factory goals. Phase II follows it, involving gathering the necessary information and conducting preliminary planning. Phase III involves the development of a general factory concept. Factors such as structures, layout planning, and identifying an ideal solution are considered. Phase IV subsequently builds upon the ideal solution by incorporating real-world constraints, integrating existing limitations, and further refining the detailed planning. Given the context of this paper, Phase II holds significant importance. In this phase, generally known as general or rough planning, factory planners face crucial decisions regarding the choice of technology [1; 39; 40]. Equally important, planners at this stage determine the level and type of flexibility to be incorporated into the production systems. Also, the specific technologies that will contribute to this flexibility are defined [41; 42]. These decisions establish the framework that subsequent planning steps must adhere to. Furthermore, specific design choices are determined based on the selected technologies at this stage. These determine the factory's layout and the fundamental operating logic in the later day-to-day business of the production system. Regarding the technology planning process, it must be considered that the choice of specific technologies strongly depends on material and workpiece geometry. It also depends on the amount and nature of features that have to be produced. These challenges have led to the development of approaches based on a classification of workpiece geometries and an automated generation of process chain alternatives for manufacturing [43]. Any such methodology must be built upon a comprehensive, quantifiable, and, whenever possible, automatable approach to characterizing workpieces. The workpiece's geometry plays a crucial role in identifying a set of possible manufacturing processes capable of realizing the required workpiece properties. Metrics independent of specific features, such as volume, volume-surface ratio, and aspect ratio, provide a general description of the workpiece. They yield specific insights into its geometric complexity. Such metrics can be calculated using existing 3D CAD files as an example. Feature-related metrics must also be considered to account for each manufacturing technology's unique opportunities and limitations [44]. Established software approaches for feature recognition enable automated metrics analysis based on CAD formats such as the STL format. Nevertheless, the effort needed to determine these features has been extremely high in the past, which led to its utilization being strongly restricted [45]. In other words, the design choices made at this stage determine the later flexibility, responsiveness, robustness, and latency of the entire production system to a major degree.