A sequencing problem to level part usage rates and work loads for a mixed-model assembly line with a bypass subline

To meet the diversification of consumer's preferences, mixed-model assembly lines were installed in many manufacturing plants. For example, in the manufacturing of trucks, a large variation exists in assembly times among different product types. The large variation reduces production efficiency and may cause a line stoppage. The variation in the assembly times can be reduced by installing a bypass subline which processes a portion of assembly operations of products with relatively longer assembly times. This paper deals with a sequencing problem with a bypass subline. The sequencing problem with goals of levelling the part usage rates and work loads is formulated, and three different algorithms based on goal chasing method, tabu search and dynamic programming are developed to solve the problem.