Work allocation strategies for serial assembly lines under high labour turnover

Abstract

Labour turnover can be very detrimental to the performance of traditional serial assembly lines. It has been shown that high turnover rates can reduce annual production throughput in serial assembly lines by more than 16% when these lines operate under a balanced work allocation strategy. This paper investigates whether alternative production methods, such as Bucket Brigades, can out-perform traditional lines by utilizing dynamic work allocation and active operator replacement policies in order to absorb better the variability introduced by labour turnover. The study performed was divided into two phases. Phase I consisted of using a simple three-station linear assembly line to compare the performance of the Bucket Brigades method against a traditional line (fixed work allocation, static operator replacement), and a method using fixed work allocation along with a dynamic replacement policy. In Phase II, a six-station serial assembly line was used to compare the performance of Bucket Brigades against the traditional balanced line method. The analyses were based on simulation models that used monthly turnover rates of 0, 6 and 12%. Phase I showed that the Bucket Brigade method outperformed the other two methods consistently when operating under moderate (6%) and high (12%) turnover rates. Phase II demonstrated that the Bucket Brigade method was better than the traditional production method in every instance, including the case with 0% turnover.