INTEGRATING KANBAN TYPE PULL SYSTEMS AND MRP TYPE PUSH SYSTEMS - INSIGHTS FROM A MARKOVIAN MODEL

Approaches to multistage production scheduling can be conveniently classified into push type (i.e., Materials Requirements Planning (MRP) systems) or pull type (i.e., kanban systems). Each is generally thought to have both advantages and disadvantages. In this paper, a hybrid push/pull strategy is developed with the aim of gaining the advantages of both approaches. Material flow between work centers is regulated using the standard single card kanban/pull arrangement. Superimposed on this is the MRP-type information flow which feeds forward demand information directly to one or more (but not necessarily all) work centers. A general N-stage hybrid push/pull model is developed. The use of the approach is illustrated using 3-stage and 4-stage serial flowlines. The results indicate that the push/pull approach has lower inventory levels and a better response to demand changes than the pure pull system. The hybrid approach seems to combine many of the advantages of MRP approaches while retaining much of the simplicity of kanban/pull systems.