Virtual Condition – GD&T
Virtual condition is the theoretical extreme boundary condition of a feature of size generated by the collective effects of MMC and any applicable geometric tolerances.
Consider above example for better understanding of virtual condition. Here MMC is Ø20.4 and a straightness tolerance 0.1 is specified at MMC. Which means that our extreme boundary is 20.5 and which is the virtual condition.
Virtual condition is extensively used by product designers to analyze mating parts, used by gauge manufactures to find the gauge dimensions and also used by product inspectors to check these extreme conditions.
Now let us take some test check your understanding on these topics.