Lot sizing with learning and forgetting in set-ups and in product quality

Managers at manufacturing firms make every effort to improve the performance of their operations through the adoption of continous improvement programmes, e.g. reducing set-ups times, increasing production capacity and eliminating rework. The learning curve can be used to describe and predict such improvements. This paper investigates the effects that learning and forgetting in set-ups and product quality have on the economic log-sizing problem. Two quality-related hypotheses were empirically investigated: (1) The time to rework a defective item reduces if production increases conform to a learning relationship, and (2) quality deteriorates as forgetting increases due to interruptions in the production process. Mathematical models are developed and numerical examples illustrating the solution procedure are provided.