17.2. RSS TOLERANCE CALCULATIONS

Now, let's use the RSS (root sum-of-squares) approach to calculating tolerances. What should be the tolerance on each part if we assume that ±3 sigma (99.73%) of the products are within tolerance?

Assume ±3 Sigma of Products Are Within Specification

Unless you have specific data showing otherwise, assume that ±3 sigma (99.73%) of the products are within tolerance. This is a general rule of thumb, since few products are made totally within specification.

Assume that in this example we want ±3 sigma of the total stack height to be within the 10" ± 0.100" tolerance specification, the same as assumed with the traditional ...

Get Statistics for Six Sigma Made Easy now with the O’Reilly learning platform.

O’Reilly members experience books, live events, courses curated by job role, and more from O’Reilly and nearly 200 top publishers.

Start your free trial