Performance impact of options for routing and delivery initiation in tugger train delivery systems

The use of lean production principles is growing and companies are increasingly focusing on small and frequent deliveries. This is often achieved through use of tugger trains carrying several part numbers, each of a relatively small quantity. To achieve time efficiency, it is necessary to design the system properly in terms of delivery routes, delivery initiation principles, delivery frequencies and buffer sizes at receiving assembly stations. This can be a challenge, especially where a large number of part variants exist and consumption rate varies according to production sequence. Based on a case from automobile industry, this paper outlines two conceptual models for tugger train delivery routing; fixed routes and variable routes. The aim is to investigate the relative performance of these two models. Advantages of fixed routes include; ease of application as they simplify administrative tasks, also repeating the route can decrease the risk of making mistakes. Furthermore, service to customers is predictable and individual. Performance is concluded in terms of time efficiency of deliveries, and how this is affected by changes in product mix and production rate. Buffer sizes and utilisation of vehicles are important variables. The paper constitutes a foundation for future research, which could verify and quantify the results presented here