Scheduling model and heuristic algorithm for roller annealing

The scheduling problem of the annealing operation of roller in an annealing shop of a roller corporation is studied. The annealing operation of roller (AOR) is a process in which the cast rough roller is processed by high-temperature furnace, low-temperature furnace and pit working procedures, and finally is formed to the roller. There are different kinds of machines in each working procedure of the annealing process and the job waiting is not allowed between any two working procedures. This problem is formulated as a no-wait hybrid flow shop (NWHFS) scheduling model, and a mathematical model to minimize the makespan is constructed and the no-wait policy is directly in the objective function. In this way, the constraints of the model are simplified and the difficulty for solving the model is reduced. A priority processing heuristic algorithm based on the processing time is proposed to solve the model. An experiment based on a set of data taken from the practical industry production demonstrates the practicality of the model and the effectiveness of the algorithm.