UNF - Unified National Fine

A Unified National Fine (UNF) thread screw is a type of threaded screw with Unified National Fine threads. UNF threads are a standardized thread form used primarily in the United States for screws, bolts, and other fasteners. UNF threads have a 60-degree thread angle, like UNC threads, but they feature a finer thread pitch.

The term "UNF thread screw" is used to describe screws or bolts that have these specific UNF threads. The thread designation is typically written as a number followed by "UNF," such as "1/4-28 UNF," where "1/4" refers to the nominal diameter of the screw, and "28" indicates that there are 28 threads per inch. This fine thread pitch makes UNF screws suitable for applications where finer adjustments and a higher level of thread engagement are required.