Mathematical Problems in Engineering
Volume 6 (2000), Issue 4, Pages 359-393

Improvability of assembly systems II: Improvability indicators and case study

S.-Y. Chiang,1 C.-T. Kuo,2 J.-T. Lim,3 and S. M. Meerkov1

1Department of Electrical Engineering and Computer Science, University of Michigan, 1301 Beal Avenue, Ann Arbor 48109-2122, MI, USA
2Department of Electrical Engineering, Tatung Institute of Technology, 40 Chungshan N. Rd., 3rd Sec, Taipei, Taiwan
3Department of Electrical Engineering, Korea Advanced Institute of Science and Technology, 373-1, Kusong-dong, Yusong-gu Taejon 305-701, Korea

Received 5 November 1999

Copyright © 2000 S.-Y. Chiang et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


Based on the performance analysis technique developed in Part I, this paper presents improvability indicators for assembly lines with unreliable machines. In particular, it shows that assembly lines are unimprovable with respect to workforce re-distribution if each buffer is, on the average, close to being half full. These lines are unimprovable with respect to buffer capacity re-distribution if each machine is starved and blocked with almost equal frequency. In addition, the paper provides indicators for identification of bottleneck machines and bottleneck buffers. Finally, the paper reports on an application of these improvability indicators in a case study at an automotive components plant.