Progressive engineering changes in multi-level product structures

One of the objectives of engineering changes is to redesign product/component parts to perform better or to be produced more efficiently. Frequent engineering changes, however, contribute to scheduling instability in multi-level product structures in addition to obsolete inventories. In this paper, we consider progressive probabilities of engineering changes as opposed to the constant probabilities generally assumed in most related studies. Realistically, the probability of changing a part at a certain level is affected by the changes in its parent levels. Thus, the likelihood of changes may progressively cascade from the top to the bottom of the product structure. An analytical procedure is developed to compute progressive probabilities of engineering changes. Then, a sensitivity analysis is performed to see how the shape of product structure and component commonality affect resultant progressive engineering changes for the lower-level items in the product structure. We find that engineering changes of a component part are affected significantly by the number of immediate parent items and their magnitudes of engineering changes. However, the depth of product structure has no significant impact on the engineering change of any item.