Alternative manufacturing sequences and tolerance buildup: a point of view and a case study

We consider alternative sequences of operations for manufacturing a given part. Within each sequence, we study the relationship between the unit-to-unit variation in the machined dimensions and the resulting variation in one or more critical dimensions (i.e. tolerance buildup). We propose an objective criterion for comparing these sequences from the point of view of their impact on the tolerance buildup at the critical dimensions. This criterion, which we refer to as the ‘total expected loss’ (TEL), is based on the concept of continuous quality loss function. We use TEL as well as the tolerance cost to compare alternative sequences for manufacturing a specific part, and present the results.