UNC - Unified National Coarse

UNC threads are a standardized thread form used primarily in the United States for screws and bolts. These threads are characterized by a 60-degree thread angle and a relatively large thread pitch. UNC threads are generally used for applications where quick assembly and disassembly are not critical, and where strength is an important consideration.

The term "UNC thread screw" is used to describe screws or bolts that have these specific UNC threads. The thread designation is typically written as a number followed by "UNC," such as "1/4-20 UNC," where "1/4" refers to the nominal diameter of the screw and "20" indicates the number of threads per inch. This means there are 20 threads in one inch of the screw.