GD&T Profile Tolerancing Applications 2 — Questions and Answers
Question 1: When a profile of a surface tolerance is applied to a curved surface, what does the tolerance zone consist of?
- Two parallel planes offset from the true profile
- Two boundaries equally disposed about the true profile surface (Correct answer)
- A cylindrical zone centered on the nominal surface
- A unilateral zone offset entirely outside the true profile
Correct answer: Two boundaries equally disposed about the true profile surface
The profile of a surface tolerance zone consists of two boundaries (inner and outer) equally disposed about the true profile unless otherwise specified.
Question 2: Which GD&T symbol is used for Profile of a Line?
- A circle with a line through it
- A semicircle open at the bottom (Correct answer)
- Two parallel horizontal lines
- A circle with a cross inside
Correct answer: A semicircle open at the bottom
Profile of a line is represented by a semicircle open at the bottom (like the letter D rotated).
Question 3: A profile tolerance applied 'all around' a part feature is indicated by:
- A note ALL AROUND in the feature control frame
- A circle placed at the junction of the leader line and the feature control frame (Correct answer)
- A flag symbol at the end of the leader line
- Brackets enclosing the entire feature control frame
Correct answer: A circle placed at the junction of the leader line and the feature control frame
The 'all around' symbol is a small circle placed at the bend/junction of the leader line where it meets the feature control frame.
Question 4: What is the primary difference between a bilateral and unilateral profile tolerance zone?
- Bilateral applies to surfaces; unilateral applies to lines only
- Bilateral distributes the tolerance equally on both sides; unilateral places it entirely on one side of the true profile (Correct answer)
- Bilateral requires a datum; unilateral does not
- Bilateral uses tighter tolerances than unilateral
Correct answer: Bilateral distributes the tolerance equally on both sides; unilateral places it entirely on one side of the true profile
A bilateral profile tolerance distributes the zone equally on both sides of the true profile, while a unilateral tolerance places the entire zone on one side.
Question 5: When profile of a surface is used without a datum reference, it controls:
- Location and orientation of the surface
- Only the form (shape) of the surface (Correct answer)
- Only the size of the surface
- Runout of the surface
Correct answer: Only the form (shape) of the surface
Without a datum reference, profile of a surface controls only the form of the feature, not its location or orientation.
Question 6: The 'all over' application of a profile tolerance means the tolerance applies:
- Around the entire perimeter of one cross-section
- To all surfaces of the entire 3D part (Correct answer)
- Only to the top and bottom surfaces
- To surfaces visible in the front view only
Correct answer: To all surfaces of the entire 3D part
Profile tolerance 'all over' applies to every surface of the entire three-dimensional part, indicated by two concentric circles on the leader line.
Question 7: In GD&T, a profile tolerance that references three datums (A, B, C) controls which combination of characteristics?
- Form and size only
- Form only
- Form, orientation, and location (Correct answer)
- Orientation and size only
Correct answer: Form, orientation, and location
When a profile tolerance references three datums, it controls form, orientation, and location of the surface relative to the datum reference frame.
GD&T Profile Tolerancing Applications 2
When a profile of a surface tolerance is applied to a curved surface, what does the tolerance zone consist of?