Cyclic Assembly Schedules for Dynamic Demands

Cyclic schedules, where fixed order interval lengths apply for all items, offer practical benefits in terms of ease of planning and control. Cyclic schedules are frequently preferred in practice, even though they result in higher total costs than non-cyclic schedules when demand is not constant. This study investigates the additional cost of cyclic scheduling in multistage assembly systems where demands vary from period to period, as in material requirements planning (MRP) environments. Capacity constraints are not included in the study.A mathematical formulation of the cyclic problem is developed, and an algorithm to solve the problem is presented. Testing is then performed to compare the costs of optimal cyclic and non-cyclic schedules. Coefficient of demand variation is the key factor affecting the additional cost of cyclic schedules. Results show that additional costs are quite moderate under a wide range of conditions.