The efficiency of balanced and unbalanced production lines

Abstract

Three previous authors have presented some evidence in support of the hypothesis that the output rate of perfectly balanced lines with variable station (or operation) times can be improved by deliberately unbalancing the lines in different ways, i.e. through different methods of assigning unequal operation times to the respective stations. This paper reports on the rather extensive computer simulation experimentation undertaken with various configurations of production lines to compare the effectiveness of the three conjectures.

Results confirm that only one of these conjectures—the ‘bowl-phenomenon’ method of assigning comparatively lower operation times to the middle stations—consistently results in better output rates than those of balanced lines as well as lines which are unbalanced in accordance with other methods. Although the ‘bowl-phenomenon’ method is found to exist in general, the extent of improvement over the output rate of balanced counterparts increases directly with the number of stations in the line and operation time variability and inversely with the interstage buffer capacity allowed in the line. Nevertheless, production lines of all lengths can be appreciably unbalanced according to the ‘bowl-phenomenon’ method without loss of output, particularly when interstage buffer capacity is small and operation time variability high.

Additional information

Notes on contributors

TARIG E. EL-RAYAH

Department of Business Administration, University of Kuwait, Kuwait.