Threaded Fasteners

Internal threads refer to those on nuts and tapped holes, while external threads are those on bolts, studs, or screws.
Threads can be produced by either cutting or rolling.
Cut threading is a process by which steel is cut away from a round bar of steel to form the threads.
Advantages of Cut Threading:
Few limitations with regard to diameter and thread length.
All specifications can be manufactured with cut threads.
Disadvantages:
Longer labor times.
The weakest area of any mechanical fastener is the minor diameter of the threads. Since the thread dimensions of a cut thread and rolled thread fastener are identical, there is absolutely no difference in strength. However, cut threading interrupts the natural grain structure of the round bar whereas roll threading reforms it.