Comparing Kanban with CONWIP in a make-to-order environment supported by JIT practices

Abstract

Adaptation of constant work-in-process (CONWIP) in make-to-order (MTO) environments essentially depends on the support of three key just-in-time (JIT) practices, i.e. unidirectional flow (UF), one-piece flow (OPF), and set-up time reduction (STR) induced by cellular manufacturing. Their impacts on the performance difference between CONWIP and Kanban were investigated by simulation experiments. CONWIP was found to be more adaptable to the dynamic shop environment since it outperforms Kanban regardless of the scenarios of the key JIT practices. The importance of UF in support of CONWIP was highlighted for a smaller STR. While a larger STR extends the effectiveness of UF, the advantage of UF in favor of CONWIP lessens at the same time. To justify the practice of OPF, an 80% or larger STR is required and CONWIP along with UF should be adopted. This study complements the current literature by establishing essential guidelines for coordinating the key JIT practices to enhance the functioning of CONWIP in MTO environments.