GD&T GD&T Virtual Condition and Boundary Concepts 2 — Questions and Answers
Question 1: What is resultant condition in GD&T?
- The worst-case boundary generated by the collective effects of LMC size and the maximum geometric tolerance (Correct answer)
- The average of the virtual and nominal conditions
- The same boundary as virtual condition but applied to datums
- The boundary when a feature is at its nominal size
Correct answer: The worst-case boundary generated by the collective effects of LMC size and the maximum geometric tolerance
Resultant condition is the worst-case boundary produced when a feature is at LMC and has the maximum allowed geometric error.
Question 2: For a pin (external feature) at LMC with a position tolerance, resultant condition equals:
- LMC minus the geometric tolerance (Correct answer)
- LMC plus the geometric tolerance
- MMC minus the geometric tolerance
- MMC plus the geometric tolerance
Correct answer: LMC minus the geometric tolerance
For a pin, resultant condition = LMC − geometric tolerance, representing the smallest envelope the pin can produce.
Question 3: What does the inner boundary (IB) represent for a hole?
- The smallest condition of the hole, equal to MMC minus the geometric tolerance (Correct answer)
- The largest condition of the hole at LMC
- The nominal bore diameter
- The virtual condition at LMC
Correct answer: The smallest condition of the hole, equal to MMC minus the geometric tolerance
Inner boundary for a hole = MMC − geometric tolerance, the tightest restriction that must still clear a mating pin.
Question 4: What does the outer boundary (OB) represent for a pin?
- The largest space the pin can occupy, equal to MMC plus the geometric tolerance (Correct answer)
- The smallest diameter the pin can be
- The resultant condition at LMC
- The nominal pin diameter
Correct answer: The largest space the pin can occupy, equal to MMC plus the geometric tolerance
Outer boundary for a pin = MMC + geometric tolerance, the largest envelope any conforming pin can produce.
Question 5: A hole has MMC = 9.8 mm and a position tolerance of 0.2 mm at MMC. What is its virtual condition?
- 9.6 mm (Correct answer)
- 10.0 mm
- 9.8 mm
- 10.4 mm
Correct answer: 9.6 mm
Virtual condition for a hole = MMC − geometric tolerance = 9.8 − 0.2 = 9.6 mm.
Question 6: Which boundary concept and modifier are used to protect minimum wall thickness or edge distance?
- Resultant condition with the LMC modifier (Correct answer)
- Virtual condition with the MMC modifier
- Inner boundary with RFS
- Outer boundary with the free-state modifier
Correct answer: Resultant condition with the LMC modifier
The LMC modifier and resultant condition ensure enough material remains at the part's thinnest point, preventing breakout or structural failure.
GD&T GD&T Virtual Condition and Boundary Concepts 2
What is resultant condition in GD&T?