The Design of Handling Process in Post-Production Stage for Precast Concrete Manufacturing

Abstract

Recently, Thailand’s construction industry has turned its attention to the precast concrete systems to improve its efficiency. Most of precast concrete factories focus on the production efficiency. However, many cases of efficiency problem occur in handling processes in post-production stage until handling wall panel onto delivery truck, as a bottleneck of the system. The purpose of this study is, therefore, to design handling process in post-production stage to efficiently satisfy production’s throughput under fluctuating market demand. Firstly, 7 Wastes of Lean, and Little’s Law are used to illustrate existing workflow and wastes, and estimate lead time and work-in-process (WIP) inventory which are turned to total holding cost. The study shows that sharp raising in throughput increases lead time significantly by 674% from regular workflow because of the congestion, double handling, and insufficient wall panel storage racks which are called A-Frame rack that directly raise total holding cost. To investigate solutions, for the first part (scenario 1-8), the model is used to experiment in reassigning of stock location, adjusting number of A-Frames, and changing to use vertical slot racks under current demand. Then, the model results suggest that 40 moveable A-Frame with improved sequence of stock location is the best practice. It reduces holding cost by 14.84%, and increases throughput by 5.52% from current system with payback period of 3.67 years. For the second part (scenario 9-17), the best practice is examined under different demand pattern. With additional 23 moveable A-Frame racks cases requires payback period of 2.92, 4.00, and 4.92 years under annual high to low demand ratio at 65:35, 50:50, and 35:65, respectively.