Setting test limits is usually done towards the end of the development phase of a product lifecycle and also during early production to ensure high yield.
Final test usually has two sets of limits. The specification limits, used for QA testing and the final test limits inset with guard bands in order to ensure that the specification is set. Guard bands should be set based on a Gage R&R study which can be carried out using GageVision.
Setting the specification limits to achieve the highest yield can be time consuming without the right tools to help. MFG Vision software provides a solution by allowing different filters to be applied to data to ensure you only consider relevant data. On this dataset limits can be calculated based on Cp or Cpk and the final limits as decided by your engineer can be tried on the production dataset and an exact actual yield value can be seen. The limits are applied to your production data which can be millions of units and the actual number of failures will be shown allowing different limits to be compared in close detail.
Customers with the yieldHUB family of products can access a detailed application note on this within the help pages.