Designing number of Kanban in glove box assembly

Abstract

For many decades, Just-In-Time manufacturing and lean manufacturing have adopted kanban system as a mean to control inventory and production. A number of tagged kanban cards represents inventory of the system, whereas untagged kanban cards equate to production orders. The ideal conditions are a consistent product mixed with a small production lot size and minimum setup time. Such conditions are difficult to obtain even in many automotive assembly lines similar to a case study. The case study assembly line is a glove box assembly production line that assembles two plastic parts and wields them together with a vibration machine after positioning in a mold designed for different products. Because of storage equipment, each kanban card represents 60 identical glove boxes. Therefore, a production engineer re-schedules the production planning to minimize the numbers of changeover without any effect on downstream. This ad hoc production scheduling leads to urgent production orders and interruption of lot size. As a result, the factory embeds historical data into a computer simulation that accounts for current molds, receiving time, and numbers of pending kanban cards, as well as number of storage equipment. The results of this simulation reveals that scheduling criteria and suggest a suitable lot size if the factory decides to change a storage equipment.