Using simulation to evaluate the introduction of a Kanban subsystem within an MRP-controlled manufacturing environment

A large assembly plant of parts for the automotive industry uses an MRP system for the mid-term planning and has developed some finite-capacity scheduling software for the scheduling of the final assembly step of its products. This software uses a heuristic which tries to respect due dates and to minimise production costs, which consist mainly of set-ups. One of the problems with this software is that it does not take the availability of subparts into consideration. In fact, the production of subparts must also deal with the problem of set-up minimisation. The difficulty lies in the fact that the technical parameters that determine ‘a good sequence’ differ for each production step. At the moment, human planners spend a lot of time and effort to coordinate and fine tune the production sequences in the various production and assembly steps. There are plans to produce some subparts of the product in a Kanban-controlled manner. A simulation model is described which allows us to study the feasibility of these plans and to determine the operational parameters (such as number of Kanbans and container size). This feasibility study was carried out for two scenarios: (1) all subpart types are produced in a Kanban controlled manner and (2) only the production of fast-movers on two (out of three) machines is Kanban controlled. The sensitivity of the results vis-à-vis a number of assumptions (set-up time reduction, machine breakdowns, tool availability, etc.) is also presented.