## 2 Theoretical Fundamentals and State of the Art
These chairs are able to provide the required infrastructure for the development of an integrated 14.0 standard value chain. As a result, by digitalizing and connecting these entities under consideration of providing interfaces for state-of-the-art software used in large enterprises, the steps undertaking to realize these objectives can be utilized by other SMEs within the metal processing environment. Depending on the product to be manufactured, the respective part has to pass various steps according to RAMI 4.0 [89]. These process steps are carried out in production facilities of various sizes, which, for the sake of simplicity, will be distinguished into SMEs and large enterprises within this work, as visualized in Figure 2. \begin{table}
\begin{tabular}{c c c} \hline \hline
**Key Technologies** & **Key Focus** & **Literature** \\ \hline Smart Factory & individualization; flexibility; decentralization; resource efficiency & [2; 40; 41; 42; 43; 61] \\ \hline CPPS & connection and cooperation of layers; acquisition and analysis of data in real-time using Internet technologies; human-machine interaction; enhance real-time decision making & [48; 49; 50] \\ \hline DT & decision making support; partial or complete representation of a production chain/process steps; simulation & [53] \\ \hline ML/Artificial Intelligence (AI) & supervised learning to enhance decision making within the production environment & [92; 93; 94; 95; 96] \\ \hline IIoT & enables in-situ data acquisition, analysis and exchange for process and production optimization & [59; 60; 62; 63; 65] \\ \hline Cloud computing & on-demand data computation in combination with IIoT & [71; 72; 73] \\ \hline DBMS & store data in structured tables linked together by keys & [41; 74; 75; 76; 77; 78; 79; 80; 97] \\ \hline IT-security & prevention of unauthorized access and data manipulation; prevention of misinterpretation and corresponding inaccurate decisions of upper layers & [81; 82; 84; 85; 86; 89; 98; 81; 82; 86; 89; 99; 88] \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Key factors and corresponding key focus according to literature. To ensure the complete digital transformation of a value chain, both SMEs and large enterprises have to meet the requirements of 1 4.0. Disruptions caused by a failure to meet this requirement, e.g., a lack of data to be integrated into the value chain, would lead to an interruption in the processing route. SMEs in particular, often lacking the financial resources and expertise to carry out a successful digital transformation process, pose a risk of such a disruption. Appropriate software and hardware is often expensive and can be a major financial barrier for some SMEs. To overcome this obstacle in terms of hardware and the associated computing resources, an approach with cloud computing is a preferable option. Another advantage would be that respective expertise does not have to be acquired by SMEs themselves, but is already available from the provider of the cloud computing service. Furthermore, providers offer additional solutions such as data processing and can thus be outsourced. Software solutions, serving as another barricade, can be managed with open or closed source products. The choice of whether to use open-source products or closed source products has to be considered from several points of view. Once again, internal know-how is a key factor for the application of open or closed source solutions. If internal human resources with IT expertise are available to implement a customized solution and the requirements and tasks are very specific, an open-source approach may be appropriate. If the requirements are non-specific as they are common in the industry, it would be preferable to use closed source products, pay license fees and thus have access to support and updates. By closing gaps in the value chain, data from other stations or companies can be accessed, depending on authorization, to enable more flexible supply chain management and process planning in the downstream and upstream steps.