A Lean Optimization Simulation Model for Mixed-Flow Production of Prefabricated Components

The development of prefabricated buildings is the key to achieving the sustainable transformation of the construction industry. The production process of prefabricated components connecting the front-end design and back-end construction plays an important role in a prefabricated building projects (PBPs). Nowadays, PBPs always adopt the mixed-flow production framework, which indicates that various types of concrete components are produced simultaneously on one production line. However, the mixed-flow production process usually falls in trouble of time delays, labor wastes, and cost overrun, these can be caused by inventory accumulation, process blockage, machine idle, etc. These activities that do not add value are identified as “waste” in lean principles. This study aims to develop a system simulation model to eliminate waste in the mixed-flow production of prefabricated components and optimize the production process within the context of lean methodologies. Take the real prefabricated component factory as the research object, and use real data to conduct research. Firstly, the current production process of components is described from two perspectives of material flow and information flow by using the value stream mapping (VSM) method to identify waste. Then, by designing future flow charts and using lean tools such as total productive maintenance (TPM), system layout planning (SLP), and just-in-time (JIT) inventory management to eliminate or improve waste, and take corresponding measures to ensure the smooth implementation of lean optimization solutions. Finally, based on the Anylogic simulation platform, the conventional and the lean-optimized prefabricated component production process are simulated, and the visualization of the production system is realized. By comparing the two systems, this research found that the lean optimization system proposed in this paper improves the productivity of precast production line. The research output contributes to the lean philosophy exploration in construction and advanced practice in prefabrication projects.