A mixed-integer programming approach to the machine loading and process planning problem in a process layout environment

A mixed-integer programming model for the machine loading and process planning problem has been developed for a process layout environment. This model relaxes the most commonly used assumption that each operation can be assigned to only one machine. In this model, the most important production cost components: machining cost, material handling cost, setup cost and machine idle cost are considered. In addition, by assigning penalty cost for long makespans, the optimal process routes for each part and optimal load for each machine in terms of minimum production cost can be obtained with lower makespan. An example problem is solved, followed by discussion with regard to the impact of batch splitting, setup cost and demand change on optimal solution.