Steelmaking-continuous casting scheduling problem with interval type 2 fuzzy random due dates

In this paper we propose a steelmaking-continuous casting scheduling (SCCS) model, where due dates are interval type 2 fuzzy random variables. Our proposed model is based on just-in-time (JIT) idea. We assign satisfaction level to charge´s completion time according to interval type 2 membership functions. Support position of membership functions depend upon the expected due dates, which are exponentially distributed random variables. In this scheduling model, limit for total waiting time between processing and waiting time before casting stage are considered as interval type 2 fuzzy sets. The interval type 2 fuzzy random optimization problem is converted to a crisp and nonlinear optimization problem by using the symmetric approach. Finally an example is presented to show the application of proposed model.