F4:Position Composite Validation
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Summary
F4 validates position composite FCFs against the ASME logic in the F4 Application and enforces segment, datum, modifier, and tolerance hierarchy rules.
Validation rules
- Only position, profile of a line, or profile of a surface are allowed in composite segments.
- Composite FCFs must have 2 to 5 segments.
- Composite position must be applied to a planar or cylindrical feature-of-size pattern.
- Datum references in lower segments must be ordered subsets of the segment above.
- For planar patterns, every segment must include datums.
- Modifiers must be identical in all segments.
- Tolerance values must decrease in lower segments.
- Prohibited modifiers: tangent plane and unequally disposed.
- Planar patterns cannot use diameter or projected tolerance zone.
- Cylindrical patterns require the diameter modifier.
Warnings and errors
F4 behavior
- Invalid composite symbol
If a composite segment uses a symbol other than position or profile, F4 flags non-compliance.
F4 behavior
- Invalid segment count
Composite FCFs must have between 2 and 5 segments.
F4 behavior
- Invalid feature pattern
Composite position must be applied to a planar or cylindrical feature-of-size pattern.
F4 behavior
- Datum hierarchy invalid
Lower segment datums must be ordered subsets of the segment above.
F4 behavior
- Modifiers inconsistent
All segments must use identical material condition modifiers.
F4 behavior
- Tolerance hierarchy invalid
Each lower segment tolerance must be smaller than the segment above.
Examples
- Valid: composite position on a pattern with decreasing tolerances and proper datum subsets.
- Invalid: composite with inconsistent modifiers or datum hierarchy.