Modelling furnace operations using simulation and heuristics

The article addresses the heat treatment operation in a manufacturing plant. The heat treatment operation is characterized by process times ranging from 7 hours to 112 hours. The immediate prior operation to heat treatment is turning. Currently, the batches loaded in heat treatment, often do not use furnace capacity adequately. The paper describes the use of heuristics and simulation to model batch loading and scheduling in the furnace operation. The batch loading operation is complex and involves issues relating to geometry, and heterogeneity in the parts and their processing requirements. Currently, the batch loading is accomplished by operator ingenuity; however, parts available from turning for loading onto the furnaces, limit the operator. The limitation on parts available for batch loading is due primarily to the use of a conventional “push” system used for scheduling. The model being proposed here has two facets to address the batch loading and scheduling problems. A heuristic based approach is proposed for the batch loading task. This heuristic forms batches for heat treatment based on anticipated production from turning; in addition, the heuristic provides feedback to turning for adjustments to its production plan. Results from a solution to the batch loading problem are integrated into a discrete event simulation model for the heat treatment and turning operations