ABSTRACT
Researchers into the mechanics of materials processing are mostly devoted to finding the load to perform an operation. This is indeed important for work-scheduling, i.e. deciding which machines are capable of applying any requisite force or power. However, there are occasions when other features may be even more important and deserving of attention. Such is the case concerning the defects and the limitations to processing, which can and do arise in products; they have tended to draw little attention from academic workers even though their economic consequences can be great.
