GD&T GD&T Virtual Condition and Boundary Concepts

Question 1

What is virtual condition in GD&T?

Accepted Answer

The worst-case boundary generated by the collective effects of MMC size and the applicable geometric tolerance

Answer

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:

Accepted Answer

MMC plus the geometric tolerance

Answer

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:

Accepted Answer

MMC minus the geometric tolerance

Answer

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?

Accepted Answer

10.3 mm

Answer

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?

Accepted Answer

Virtual condition

Answer

A go gauge is sized to the virtual condition so it accepts every conforming pin while rejecting those that violate the worst-case boundary.

(GD&T) Geometric Dimensioning and Tolerancing Certification Practice Test