GD&T Composite Feature Control 5 — Questions and Answers
Question 1: In a composite profile callout, the lower-segment tolerance zone is described as a uniform-width band. This band is allowed to:
- Expand beyond the upper-segment band
- Translate and/or rotate relative to the true profile, within limits set by the upper segment (Correct answer)
- Change shape relative to the nominal profile
- Apply only to internal profiles
Correct answer: Translate and/or rotate relative to the true profile, within limits set by the upper segment
The lower-segment profile tolerance zone can translate and rotate relative to the true profile position, but it must remain entirely within the upper-segment tolerance zone.
Question 2: A designer specifies composite position with PLTZF ⌀0.5 and FRTZF ⌀0.5. What is the practical effect?
- The FRTZF has no additional restraint beyond the PLTZF (Correct answer)
- The feature spacing is twice as tight as the pattern location
- The PLTZF is redundant and can be eliminated
- The two zones create a spherical tolerance zone
Correct answer: The FRTZF has no additional restraint beyond the PLTZF
When PLTZF and FRTZF have equal values, the lower segment provides no additional tightening of feature-to-feature relationships beyond what the upper segment already requires.
Question 3: Under ASME Y14.5, a composite feature control frame is distinguished from a two single-segment frame by:
- The composite frame uses two separate geometric characteristic symbols
- The composite frame uses one geometric characteristic symbol spanning both rows (Correct answer)
- The composite frame requires MMC in both segments
- The composite frame applies only to cylindrical features
Correct answer: The composite frame uses one geometric characteristic symbol spanning both rows
A composite frame has a single geometric characteristic symbol (e.g., position circle) that extends vertically across both rows, while a two single-segment frame repeats the symbol in each row independently.
Question 4: For a composite position callout, which statement about the FRTZF zone orientation is correct when datum A (a flat surface) is the only FRTZF datum?
- The FRTZF zones are free to translate in X and Y but are locked in rotation about all axes
- The FRTZF zones must remain perpendicular to datum A but may translate in X and Y (Correct answer)
- The FRTZF zones are free to translate in all directions and rotate about all axes
- The FRTZF zones are locked to the true position relative to datum A
Correct answer: The FRTZF zones must remain perpendicular to datum A but may translate in X and Y
With only datum A (primary flat surface) in the FRTZF, the zones must remain perpendicular to A (orientation locked) but can translate freely in X and Y within the PLTZF boundaries.
Question 5: A part drawing shows composite position with PLTZF ⌀0.8|A|B|C and FRTZF ⌀0.3|A|B|C. This is functionally equivalent to:
- A single position callout of ⌀0.3|A|B|C
- Two single-segment callouts of ⌀0.8|A|B|C and ⌀0.3|A|B|C (Correct answer)
- A profile callout of 0.4|A|B|C
- A composite callout with no PLTZF datums
Correct answer: Two single-segment callouts of ⌀0.8|A|B|C and ⌀0.3|A|B|C
When all three datums appear in both segments of a composite frame, it is functionally equivalent to two single-segment position callouts because the FRTZF is fully constrained with no freedom to translate or rotate.
Question 6: Which of the following is a valid reason to choose composite tolerancing over a tighter single position tolerance?
- To avoid specifying datums on the drawing
- To allow more variation in pattern location relative to datums while ensuring parts assemble correctly with mating features (Correct answer)
- To eliminate the need for functional gauging
- To apply different geometric characteristics to the same feature
Correct answer: To allow more variation in pattern location relative to datums while ensuring parts assemble correctly with mating features
Composite tolerancing allows a loose location tolerance for assembly into a housing while maintaining tight feature-to-feature spacing needed for mating with a bolt pattern, optimizing manufacturability.
Question 7: When applying composite position to a non-circular pattern (e.g., rectangular slots), the FRTZF tolerance zones are:
- Always cylindrical regardless of feature shape
- Shaped to match the tolerance zone type appropriate for the feature (e.g., width zones for slots) (Correct answer)
- Converted to a bilateral profile tolerance
- Applied only to the center plane of each slot
Correct answer: Shaped to match the tolerance zone type appropriate for the feature (e.g., width zones for slots)
For slot patterns, the FRTZF tolerance zones are parallel-plane (width) zones that match the center-plane geometry of the slots, not cylindrical zones.
GD&T Composite Feature Control 5
In a composite profile callout, the lower-segment tolerance zone is described as a uniform-width band.
This band is allowed to: