Screw and Screw Threads

A screw is a cylindrical or a conical rod with a helical groove cut on it. Its function is to transform the input motion of rotation into output motion of translation. A screw thread is a continuous helical ridge formed by cutting a helical groove on a cylindrical or conical shank. Basically screw threads are used to fasten the parts together, or to transmit motion and so power, or for the relative adjustments of the adjacent parts. To perform these specific functions, threads of different profiles are used. The shape of the different types of the standard thread profiles with proportions and their suitability for specific purpose are discussed here.