- A proposal for production control by multi-scale hierarchical modeling-

Integrated optimization of production in the steel industry to simultaneously minimize lead time and improve productivity is a real challenge. Lean manufacturing, recognized as a leading successful example of such optimization, is characterized by synchronization of time scale of production with that of the mainline. However, in the steel industry, it is inherently difficult to implement synchronization and reduction of production time to the same degree as in the automobile industry. This difficulty motivated our method for integrated optimization of production at the plant level in the steel industry, by modeling the production control as a multi-scale hierarchical structure in time. This paper describes an attempt to systematize production knowledge in industry by a synthesis of practical knowledge (of shopfloor engineers) and company experiences.