Assessment of Alternative Assembly Line Arrangements with Variable Operation Times

Abstract

The main objective of this research was to assess alternative line arrangements with variable operation times through the use of a computer simulation model. A bowl versus inverted bowl and increasing versus decreasing mean times line arrangements were evaluated for normal and exponential distributions with variances equal to 1 and 16. Three assessment criteria were used: (1) the total elapsed time to complete 500 units, (2) the percentage of working time, and (3) the average time in the system. The effect of imbalance parameters on the assessment criteria was determined for the line arrangements. The results show that the inverted bowl is superior to the bowl arrangement for a normal distribution in terms of the total elapsed time criterion, however, with an exponential distribution, the bowl is found better than inverted bowl. On the basis of the percentage of working and the average time in the system criteria for a normal distribution, the bowl is found superior to the inverted bowl. Similar results are obtained for an exponential distribution with variance = 1, but no definitive inference can be made with variance = 16. The optimization of one assessment criterion for a particular imbalance value does not necessarily optimize the other criteria. For only the bowl arrangement with an exponential distribution and variance = 1, all the criteria are optimized for an imbalance value of zero.