Operations planning for a single-stage kanban system operating under linear demand

A production line with a single-stage kanban system which works between two adjacent workstations is considered here. Raw materials are replenished at the first workstation and processed through the workstations resulting in the final product for dispatching to the next demanding point which could be either an external buyer or a feeding point to the same or another production line. The kanban which transports the work-in-process from the first station to the second works as a circulating mechanism between the stations. When the demand and the production rates remain constant, the batch sizes of work-in-process remain constant, but if the demand of the products varies over time, the batch size of the kanban system remains no longer unaffected. A study is pursued in this research to determine the number of kanbans between two workstations for a varying (linear) demand pattern. This decision eventually determines batch sizes of the kanbans, the dispatching time intervals, and the schedule for production. In order to achieve this goal, this problem is formulated as an inventory model dealing with raw materials, work-in-process and finished goods inventory. The problem is solved optimally, and the number of kanbans and the batch sizes are scheduled based on the demand pattern of products. Results of the model are demonstrated to show the operational mechanism of the kanbans between the workstations.