Abstract
This paper introduces a simulation-based Digital Twin (DT) framework designed to support integrated Factory and Production Planning (FPP). The framework combines Digital Factory Planning (DFP) with Discrete Event Simulation (DES) to enable dynamic analysis and optimization of manufacturing systems. Digital Twin Prototype (DTP) was developed to model one-piece-flow-based assembly line configurations, grounded in requirements provided by an industrial partner. Simulation experiments conducted within the DTP environment aimed to identify bottlenecks and assess the impact of varying input parameters on key performance indicators (KPIs), including transportation effort, lead time, resource utilization, and economic feasibility. The results highlight that optimized system configurations can significantly improve resource utilisation, reduce operational costs, and shorten lead times. In the future, the DTP will be further developed to enable the transition towards a Digital Twin Instance (DTI) and eventually a Digital Twin Aggregate (DTA), through integration with real-time data and enhanced simulation fidelity.