Level Scheduling for batched JIT supply

Abstract

A mixed-model assembly line requires the solution of a short-term sequencing problem which decides on the succession of different models launched down the line. A famous solution approach stemming from the Toyota Production System is the so-called Level Scheduling, which aims at distributing the part consumption induced by the model sequence evenly over time. Traditional Level Scheduling seeks to closely approximate target demand rates at every production cycle, however, such a strict leveling is only required if parts are directly pulled from a connected feeder line. In real-world assembly lines, parts are predominately delivered in (small) batches at certain points in time. In such a situation, a Just-in-Time supply is already facilitated whenever the cumulative consumption is leveled in accordance with each part’s delivery schedule, while the exact consumption pattern between two delivery points seems irrelevant. The paper on hand provides new Level Scheduling models, proves complexity, presents exact and heuristic solution procedures and shows inferiority of traditional Level Scheduling for such a batched JIT-supply of parts.