Tolerancing is a complex procedure. This article serves as an overview of the process, which is:
  • Optimize your design until it exceeds the target specification by some reasonable margin
  • Build a set of default tolerances. Where ZEMAX offers more than one way to tolerance the same parameter, choose the one that represents the method used in actual tmanufacture, test or assembly
  • Edit the tolerances to account for the mounting arrangements and add any compensators
  • Define a tolerance criterion that represents what the actual test on the shopfloor is
  • Build some Monte-Carlo files and test that the tolerances are being implemented in the way you expect.
  • Perform a Sensitivity analysis
  • Tighten troublesome tolerances by hand, or use Inverse Sensitivity
  • Once you have confidence in your tolerances, build at least n2 Monte-Carlo files, where n is the number of tolerances
  • Review the tolerances produced by inverse tolerancing, and ensure they are reasonable.

Remember that not every design you start with will be buildable with cost-effective tolerances. It may be that in order to achieve your goal of a buildable design, you need to analyze several competing designs. See the many other articles in the Knowledge Base Tolerancing category, and the User's Guide for more information.