An Open Framework for Smart Retrofitting of Legacy Industrial Machines Towards Industry 4.0

This paper presents a six-layer framework for smart retrofitting of legacy industrial machines to align with Industry 4.0 standards, using open-source technologies for cost-effectiveness and scalability. The layers include edge data acquisition, data preprocessing, Digital Twin technology, long-term data storage, AI-based data analysis, and real-time visual-ization. Implemented and evaluated through a case study on a legacy CNC lathe, the framework demonstrated reliable communication and effective performance across various layers. The results validate the framework's feasibility and highlight the need for further fine-tuning of open large language models with manufacturing domain knowledge.