KATSUKI AOKI and ROSS MOUER
Meiji University, Japan
Just-in-time production (JITP) was conceived at the Toyota Motor Company in 1938 by Ki-ichiro Toyoda. That vision evolved into what is now known as the “Toyota Production System” (TPS), owing mainly to the efforts of Tai-ichi Ono during the 1950s. JIT is one of two pillars of TPS; the other is “autonomation” (automation with a human touch), which was developed by Sakichi Toyoda. JITP is a system used by manufacturers to order and obtain processed parts through a highly developed network of subcontracting firms. JITP represents a further development of the Ford production system that facilitated the transition from mass production to small lot sizes, and reduced the cost of holding large inventories of the parts required on conveyor-based assembly lines. JITP calls for the right parts to be supplied to the production line by suppliers only at the time they are needed and only in the amount needed. JITP relies on the use of kanban. The kanban is a material flow control mechanism to communicate effectively with internal and external operations on issues such as adjusting inventory levels, production schedules, and lead times for the delivery of parts. Heijunka (production leveling) also plays a key role in JITP, with the aim of leveling out the quantity of parts that are sent up the supply chain, thereby smoothing flow on the production line.
Variants of Toyota's kanban ...