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Zorluk: OrtaBolts, Nuts, and Washers

A mechanic is reviewing a technical parts manual to replace damaged hardware on a heavy equipment mounting plate. The specification calls for a 3/8-16 UNC×1-1/2 in3/8\text{-}16\text{ UNC} \times 1\text{-}1/2\text{ in} hex cap screw. In this standardized Unified National fastener callout, what does the number 1616 represent?

  1. A
    The outer diameter of the bolt head in sixteenths of an inch
  2. B
    The recommended metric wrench size of 16 mm16\text{ mm} required for installation
  3. The number of threads per inch along the bolt shankCevap
  4. D
    The minimum tensile yield strength rating of 16 ksi16\text{ ksi}

Cevap

The number of threads per inch along the bolt shank
In standard imperial fastener nomenclature (Unified Thread Standard), the number immediately following the nominal diameter indicates the thread pitch, defined as the number of threads per inch (TPI). In 3/8-16 UNC×1-1/2 in3/8\text{-}16\text{ UNC} \times 1\text{-}1/2\text{ in}, 1616 specifies that there are 1616 complete thread crests per inch along the shank.

Adım Adım Çözüm

1
Analyze the standard SAE Unified National thread callout format
The standard nomenclature is formatted as: [Nominal Diameter] - [Threads Per Inch] [Thread Series] x [Fastener Length].
Deconstructing the callout reveals the distinct mechanical property defined by each segment.
2
Map each value from 3/8-16 UNC×1-1/2 in3/8\text{-}16\text{ UNC} \times 1\text{-}1/2\text{ in} to its corresponding dimension
3/8 in3/8\text{ in} is the nominal major diameter, 1616 is the thread pitch (threads per inch), UNC\text{UNC} indicates Unified National Coarse, and 1-1/2 in1\text{-}1/2\text{ in} is the overall length measured from under the bolt head.
The second parameter in imperial fractional fastener callouts always specifies the thread density per linear inch.

Anahtar Kavram

Standard Unified National (SAE) fastener callout nomenclature
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