Improving performance using workforce flexibility in an assembly environment with learning and forgetting effects

Competitive pressures for assemble-to-order products and products with shorter life cycles have driven the need for more flexibility in assembly operations. This paper explores the use of workforce flexibility as a means for improving the performance of assembly operations. Two decisions that immediately affect the performance of assembly operations are the amount of cross training to give to each worker and the dynamic deployment policies for assigning workers to tasks. In environments where learning and forgetting are present, these decisions are interrelated. The effectiveness of these two decisions is a function of the product line profiles of the assembled products. We define the product line profile using two factors: product variety and task complexity. Using a simulation model of an assembly line and an experimental design that incorporates product variety and task complexity, we show that as task complexity increases, deployment should be restricted while only low cross training is needed, and as product variety increases, cross training should be increased but deployment should be kept flexible. When both task complexity and product variety increase cross training should increase but deployment should be restricted. When task complexity and product variety are low, a moderate amount of cross training with flexible deployment of workers is best.