American Standard Thread is a widely used threading system in North America. It is characterized by a 60-degree thread angle and standardized pitch measurements. The thread profile shows the major diameter at the thread peaks, minor diameter at the thread roots, and the pitch distance between adjacent threads.
American threads use a standardized designation system. For example, one-quarter dash twenty UNC means a quarter-inch diameter thread with twenty threads per inch in the Unified National Coarse series. UNC threads have fewer threads per inch compared to UNF or Unified National Fine threads, making them easier to manufacture and assemble.