Economic manufacture quantity (EMQ) model with lot-size dependent learning and forgetting rates

Optimal lot-size formulae typically assume that unit manufacturing costs are constant. This is not true while learning is in progress. Many researchers have studied the effect of learning on the lot-size problem. These works commonly assume an invariant learning slope throughout the production–planning horizon. When learning rates (LRs) are dependent on the number of units produced in a production cycle, then the assumption of invariant LRs might produce erroneous lot-size policies. This paper investigates the effect of lot-size dependent learning and forgetting rates on the lot-size problem by incorporating the dual-phase learning–forgetting model into the economic manufacture quantity model. Numerical examples are provided to illustrate the solution procedure. These compare different approaches to lot sizing with learning and forgetting effects.