GD&T Resultant condition

A brief explanation on the meaning of Resultant condition in GD&T and how is it different from Virtual condition when Position control is used .

To understand the concept of resultant condition which is related to virtual condition , take this example for reference .

The possible positional deviations for a shaft manufactured at MMC (20.2) would be

The positional deviation allowed at MMC is 0.1 (no Bonus tolerance)

If we scribe a circle enveloping all possible worst case positions at MMC then we get an Outer boundary as shown .

This is called as virtual condition.

Similarly if we take the shaft to be manufactured at LMC which is 19.8 and consider all possible position deviations , here the tolerance is Geometric tolerance + Bonus tolerance which is 0.5

The inner boundary shown in red hashed lines is calculated as LMC – Total positional tolerance which is 19.8 – 0.5 = 19.3 mm

This inner boundary is called as Resultant condition for the pin .

To summarize for a shaft (external feature of size ) with a Maximum material condition modifier attached to geometric tolerance in feature control frame the Outer boundary is the virtual condition and Inner boundary is called as the resultant condition.

For a hole (internal feature of size) the definition of resultant condition is the outer boundary and not the inner boundary , hence the table will be different .

Learn more about how to Interpret GD&T callouts from this e-book on GD&T interpretations