Using Simulation to Understand and Optimize a Lean Service Process

This paper describes the application of discrete event simulation to understand and optimize a lean service process. Simulation is being used increasingly in the design and improvement of lean manufacturing systems. We now apply simulation to the emerging notion of lean service. We use the case study of a lean auto repair facility to demonstrate the significant role that simulation can play in the design of a costeffective system. This lean service system eliminates queues by carefully scheduling appointments. A consequence of this type of system is that customers may sometimes need to wait for a considerable time outside the system before the start of their appointments. Our simulations show that the “time to appointment” can be optimized in conjunction with other metrics such as utilization of repair technicians and work in process. Simulation can clarify the exact nature of the tradeoff between customer satisfaction and cost-effective delivery of service. Our simulations also show that perturbations introduced by customers arriving late to their appointments can be absorbed with minimal impact provided there is some slack in the system. This finding may help to ameliorate one of the primary concerns regarding the lean service model.