Job and product rotation for maximising the production output on multi mixed-model assembly lines for element prefabrication in industrialised housebuilding

This paper analyses the production planning for the multi mixed-model assembly lines (MMMAL) for building elements prefabrication. Industrialised housebuilding (IHB) prefabrication plants struggle with increasing the productivity of existing prefabrication equipment through the application of traditional planning methods. This research aims to apply a linear programming model to solve this planning problem. To test the model a wall element prefabrication plant with three distinct lines formed the test ground. Three scenarios are defined and evaluated to map job and product rotation, this is to generate more flexibility and enable better response to bottlenecks. The model is implemented to determine the optimal solution for each scenario and the experiments were done with real production data. Firstly, the formation of floater groups to improve worker scheduling and, secondly, the product rotation, is expanded to circumvent production bottlenecks. In a third scenario, the previous two are combined. The linear optimisation model allowed to improve the production planning for MMMAL by increasing the output by more than 50 % compared to the initial situation. Additionally, more than 70 % skilled worker resources can be saved. The contribution of this paper is that it shows the improvement potential in production planning for MMMAL through the application of an optimisation model using a combination of job and product rotation.