A method of maintaining flow between disconnected processes. Such processes may be separated, for example, because a step that takes place outside the line or plant is too expensive or bulky to move. Using a pull-FIFO technique, tsurube ensures that a standard number of parts exit and re-enter the system in sequential order. Tsurube houshiki is the Japanese term for a system for using two buckets to draw water from a well; an empty bucket goes down while a full bucket - attached to the same rope, running through a pulley - comes up.
In the example, where part of a value stream is shown, a tsurube system maintains flow between the main process and heat treatment. Every twenty minutes, a fixed number of items arrive at the heat treatment FIFO street from the FIFO street after operation 20. In addition, every twenty minutes, the same number of items are transported from the heat treatment FIFO street to the FIFO street for the next step, operation 40. The FIFO lanes
adhere to the order of items to be processed. (The solid blue arrows represent the material flow through the operations.)
Thanks to timed delivery and dispensing, managers know within 20 minutes if there are problems. To improve the system, managers should consider why heat treatment is isolated and how that step can be linked to the system. Stable production processes are a prerequisite for implementing a tsurube system to maintain flow and pull production.