Composite Feature Control Flashcards

In a composite feature control frame, the upper segment is called the:

Answer: Pattern-Locating Tolerance Zone Framework (PLTZF)

The upper segment of a composite feature control frame is called the Pattern-Locating Tolerance Zone Framework (PLTZF), which controls the location of the pattern as a whole.

Which datum references are typically included in the Feature-Relating Tolerance Zone Framework (FRTZF) of a composite callout?

Answer: Only orientation datums, no location datums

The FRTZF typically references only orientation datums (like datum A for perpendicularity) but not location datums, since it controls feature-to-feature relationships rather than absolute location.

A composite positional tolerance has PLTZF of ⌀0.8 and FRTZF of ⌀0.3. What does ⌀0.3 control?

Answer: The spacing between individual features within the pattern

The FRTZF tolerance of ⌀0.3 controls the spacing and orientation of features relative to each other within the pattern.

Can a composite feature control frame be used with profile of a surface tolerances?

Answer: Yes, composite profile tolerances are explicitly defined in ASME Y14.5

ASME Y14.5 explicitly defines composite profile tolerances, where the upper segment controls location and the lower segment controls form, orientation, and feature-to-feature relationships.

When a datum reference is repeated in both the PLTZF and FRTZF of a composite callout, what does it mean in the lower segment?

Answer: It restricts the FRTZF from translating relative to that datum

When a datum is repeated in the FRTZF, it restricts translation of the tolerance zone relative to that datum while still allowing the zone to shift in other directions.

Two single-segment position callouts differ from a composite callout because:

Answer: Each segment of a two single-segment callout independently locates features from its referenced datums

In a two single-segment callout, each segment independently locates features from its own datum references, whereas the FRTZF in a composite callout controls only feature-to-feature relationships.

In composite tolerancing, which condition must always be true regarding the PLTZF and FRTZF tolerance values?

Answer: PLTZF must be larger than or equal to FRTZF

The PLTZF tolerance must always be equal to or larger than the FRTZF tolerance, since the FRTZF zone must fit within the PLTZF zone.

An MMC modifier is applied to the FRTZF of a composite position callout. What benefit does this provide?

Answer: It provides bonus tolerance for feature-to-feature location as features depart from MMC

An MMC modifier on the FRTZF allows each feature's tolerance zone to increase (bonus tolerance) as the feature departs from MMC, while still maintaining pattern geometry.

A composite callout has PLTZF|A|B|C and FRTZF|A|B. Compared to FRTZF|A only, what additional constraint does adding datum B impose?

Answer: Restricts rotation about the datum B axis

Adding datum B (typically a secondary datum) to the FRTZF restricts the rotational degree of freedom about the axis perpendicular to datum B, locking the pattern's clocking.

For a pattern of four holes using composite position, how many total cylindrical tolerance zones must each physical hole simultaneously satisfy?

Answer: Two

Each physical hole must satisfy two cylindrical tolerance zones simultaneously: one from the PLTZF and one from the FRTZF.

In ASME Y14.5-2018, which symbol is used to indicate 'Separately' when the simultaneous requirement should NOT apply to composite callouts on the same drawing?

Answer: SEP

The notation 'SEP REQT' (Separately) is added to indicate that multiple geometric tolerances referencing the same DRF should be verified independently rather than simultaneously.

A composite positional tolerance controls a pattern of slots. The FRTZF is wider than the individual slot tolerance zone. This situation is:

Answer: Invalid because the FRTZF must always be smaller than the PLTZF

The FRTZF tolerance must always be equal to or smaller than the PLTZF tolerance, since the FRTZF zones must fit within the PLTZF framework.

Which of the following best describes the 'float' allowed by the FRTZF in composite tolerancing?

Answer: The entire FRTZF pattern of zones shifts as a rigid group within the PLTZF zones

The FRTZF tolerance zone framework shifts and (if no orientation datums are cited) rotates as a rigid group, maintaining the pattern geometry while accommodating location variation.

When verifying composite position with a functional gauge, which segment drives the gauge hole locations?

Answer: The PLTZF drives the absolute pattern location; a separate gauge checks FRTZF

A PLTZF functional gauge locates holes at true position relative to the datum reference frame; a separate FRTZF gauge checks the feature-to-feature geometry with holes at the FRTZF tolerance size.

In a composite profile callout, the lower-segment tolerance zone is described as a uniform-width band. This band is allowed to:

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.

A designer specifies composite position with PLTZF ⌀0.5 and FRTZF ⌀0.5. What is the practical effect?

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.

Under ASME Y14.5, a composite feature control frame is distinguished from a two single-segment frame by:

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.

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?

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.

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:

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.

Which of the following is a valid reason to choose composite tolerancing over a tighter single position tolerance?

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.