Presentation Slides


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Arizona State University and TRW are currently working together in an innovative production system which aims to minimize the impact of labor turnover and absenteeism to assembly line throughput. The new production system is based on a one-piece flow, pull type production method that utilizes dynamic work allocation and operator replacement techniques at a passenger airbag assembly line of the TRW Chihuahua OR plant. The project was divided into three phases which included data gathering, development of the simulation models of the new and previous production system, and implementation of the new production system followed by supervision/auditing of the implemented system. The actual implementation of the new production system took place on December the 3rd 2001.


A self-balancing line (bucket brigade)  was first proposed by Bartholdi and Eisenstein to build more flexible lines, where each worker carries an item from station to station until interrupted by the subsequent worker.  After the worker has surrendered his part he/she walks back take over the item of his/her predecessor.  In this system, operators are sequenced from slowest to fastest, while the assembly line arrives by itself to a point of equilibrium, and therefore, no “balancing” of the line is required.


The principle of Bucket Brigade is similar to that of the relay race, in that the least experienced runner (slowest) initializes the assembly process and the more experienced one (fastest) finalizes it in order to make up for any lag.  A “brigade” organizes the associates in such manner that the line balances itself.  The associates will work as a production system that will organize itself.  The goal of each associate is to finish the harness and not only fulfill the operations assigned to his workstation.

When the associate of station 6 finishes the harness, he takes over the harness of the previous associate of station 5 , and takes it over to his station.  The associate of station 5 takes over the harness of the associate at station 4 and this same process continues down the assembly line.  Associate of station 1 introduces a new item to the line.


The line consistently reaches and sometimes exceeds the daily production quota even though personnel turnover rate is high.  Level changes (set up) are quicker since the WIP is lower than with the pre-existing method.  The leader of the line prefers BB since it is easier to supervise the operators and change levels.  The mentality of teamwork is enhanced.