BUS606: Operations and Supply Chain Management

Today's manufacturing environment is highly time varying, and most of the components in the supply chain have stochastic nature of objectives and constraints due to environmental uncertainties and executional uncertainties. These uncertainties can be triggered by machine breakdowns, shortage of materials, interruption of machine operations when their performance violates quality control standards, etc. The occurrence of interruptions and the time required for assembly to resume from the interruptions are often highly stochastic in nature. These issues always lead to unexpected delays in assembly. The deterministic schedule obtained prior to the start of assembly processing is affected and becomes inappropriate. Thus, the deterministic schedule should be updated so as to minimize the disturbances due to uncertainties. The scenario of assembly process delays caused by the stochastic events is studied and a schedule repair heuristic is presented to minimize the influence of stochastic events on deliveries. 

There are two types of orders, viz., regular (non-delayed) orders and delayed orders. Regular (non-delayed) orders are the orders that are released into the shop as per the predetermined transportation allocation. Orders that have not been processed in assembly because of unexpected uncertainties are referred as delayed orders. The decision consists of the schedule of the delayed orders which have missed their earlier departure due-dates along with non-delayed orders. A delay is characterized by a start time and duration. It may result from machine breakdowns, shortage of materials, interruption of machine operations when their performance violates quality control standards, etc. The jobs completed prior to the delay are not taken into account. Hence, this section considers a situation of rescheduling the delayed orders along with non-delayed orders with a possibility of identifying a sequence in which non-delayed orders in the original schedule can reach their destination on time. It is also to be stated again that if an order misses it scheduled departure time it can only be shipped by a commercial fight at a higher cost. Basically, this possibility is considered to avoid a situation of very high disruptions caused in relation to the customer deliveries.