The included flank angle for Unified and American National thread profiles is___________________?
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Answer: A. 60°
Explanation
Unified and American National thread profiles are standardized with an included flank angle of 60 degrees. This 60-degree angle provides an optimal balance between thread strength and ease of manufacturing. Standard screw gauges and cutting tools are specifically ground to match this precise flank angle. Flank angle is the angle between the individual flanks of a screw thread measured in an axial plane. Unified Thread Standard unifies British American and Canadian fastener designs for global interchangeability. Standardized thread geometry ensures that bolts and nuts from different manufacturers fit together perfectly.
These 60-degree threads are used in millions of commercial fasteners throughout North America and globally. Machinists select specific threading tool inserts designed for standard Unified National thread profiles. Maintaining correct flank angles ensures proper load distribution across engaged thread surfaces. An included angle of 55 degrees is characteristic of British Standard Whitworth thread profiles. Smaller angles like 29 degrees are used for ACME power transmission screw threads. Metric ISO threads also adopt the standard 60-degree included flank angle design.
- Subject
- Engineering
- Category
- Mechanical Engineering
- Topic
- —
- Difficulty
- medium
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