Multi-project and Procurement Scheduling for Manufacturing-to-order Environments under Price Inflation

Production planning in manufacturing-to-order (MTO) environments has been treated by several researchers as a project scheduling problem, in which customers’ orders are assumed to be different projects that rely on several shared resources. Processing several orders at the same time extends this problem to the resource-constrained multi-project scheduling problem (RCMPSP), while only single projects are considered in the relevant literature. A primary issue for this problem is procurement scheduling, which is handled using integrated project scheduling and material ordering (PSMO) models; however, existing PSMO models do not consider inflation-related costs caused by the ordering times for procurement items. In this paper, MTO production planning is modeled as a resource-constrained multi-project scheduling problem integrated with procurement scheduling under inflation. The proposed model reduced the delay by 72.7% on average and also reduced the delay penalties by 54% on average, compared to the current status of the case study.