Production control in precast fabrication: considering demand variability in production schedules
On-time delivery is a key factor in the business success of precast fabricators. The greatest obstacle to achieving this goal is demand variability. The objective of this research is to develop a plan that continuously improves production control systems for precast fabrication. This plan involves a lead time estimation model (LTEM) and schedule adjustment principles. The LTEM is established to estimate the impact of demand variability. In the model, previous jobs are analyzed as indicators of customer behavior. Using the captured behavior, fabrication lead time can be estimated for forthcoming projects. Two principles are proposed to adjust the production schedule according to the estimated lead times. Two adjustment principles are designed to reduce the impact of demand variability: (1) start fabrication later relative to the required delivery dates and (2) shift production milestones backward to the end of the production process. The effectiveness of the developed improvement plan including LTEM and the adjustment principles were validated using a real precast fabricator. The proposed approach is one of the first studies to use historical data to estimate the impacts of demand variability based on customer behavior.