GD&T GD&T Virtual Condition and Boundary Concepts 1 — Questions and Answers
Question 1: What is virtual condition in GD&T?
- The worst-case boundary generated by the collective effects of MMC size and the applicable geometric tolerance (Correct answer)
- The nominal drawing size of a feature
- The maximum material condition of a feature without geometric tolerance
- The average of all measured boundary positions
Correct answer: The worst-case boundary generated by the collective effects of MMC size and the applicable geometric tolerance
Virtual condition is the worst-case boundary produced by combining MMC size with the full geometric tolerance, used for functional gauging.
Question 2: For an external feature (pin) at MMC with a position tolerance, virtual condition equals:
- MMC plus the geometric tolerance (Correct answer)
- MMC minus the geometric tolerance
- LMC plus the geometric tolerance
- LMC minus the geometric tolerance
Correct answer: MMC plus the geometric tolerance
For a pin (external feature), virtual condition = MMC + geometric tolerance, giving the largest boundary the pin can occupy.
Question 3: For an internal feature (hole) at MMC with a position tolerance, virtual condition equals:
- MMC minus the geometric tolerance (Correct answer)
- MMC plus the geometric tolerance
- LMC minus the geometric tolerance
- LMC plus the geometric tolerance
Correct answer: MMC minus the geometric tolerance
For a hole, virtual condition = MMC − geometric tolerance, representing the smallest the hole boundary can be.
Question 4: A pin has an MMC of 10.2 mm and a perpendicularity tolerance of 0.1 mm at MMC. What is its virtual condition?
- 10.3 mm (Correct answer)
- 10.1 mm
- 10.2 mm
- 10.0 mm
Correct answer: 10.3 mm
Virtual condition for an external feature = MMC + geometric tolerance = 10.2 + 0.1 = 10.3 mm.
Question 5: A functional (go) gauge designed to check a pin is sized to which boundary?
- Virtual condition (Correct answer)
- Resultant condition
- LMC size
- Nominal drawing size
Correct answer: Virtual condition
A go gauge is sized to the virtual condition so it accepts every conforming pin while rejecting those that violate the worst-case boundary.
Question 6: Virtual condition applies specifically when which modifier is called out in the feature control frame?
- MMC (Maximum Material Condition) (Correct answer)
- RFS (Regardless of Feature Size)
- LMC (Least Material Condition)
- Free State
Correct answer: MMC (Maximum Material Condition)
Virtual condition is tied to the MMC modifier; it defines the fixed worst-case boundary against which functional gauges and mating parts are designed.
GD&T GD&T Virtual Condition and Boundary Concepts 1
What is virtual condition in GD&T?