Determining the throughput of a CONWIP system using adjusted ARM

Purpose: The purpose of this paper is to propose an adjusted approximate regenerative model (ARM) for a constant-work-in-process (CONWIP)-based production system that solves the problem of deciding the number of intermediate bulk container in a pharmaceutical company to hold the work in process. Design/methodology/approach: The problem was modeled as a CONWIP system and the ARM was adjusted to estimate the throughput. Findings: By comparing the results from the original ARM and adjusted ARM, a clear superiority of the proposed method is shown for the real case. In addition, the robustness of the adjusted ARM is demonstrated in terms of the violation of rigid assumption and the impacts brought by the limitation of buffer space before the bottleneck station. Originality/value: The novelty of the proposed model is to take the long transportation time between machines into consideration.