Gjengestørrelse

Gjengestørrelse refers to the dimensions of a screw thread. It is a critical parameter that defines the interchangeability of fasteners. The primary dimensions considered are the major diameter, pitch, and thread form. The major diameter is the largest diameter of the screw thread. The pitch is the distance between adjacent threads. The thread form describes the shape of the thread profile, such as triangular, square, or trapezoidal.

For metric threads, the size is typically specified by the nominal major diameter in millimeters followed by the pitch in millimeters, for example, M10 x 1.5. M indicates a metric thread, 10 is the major diameter, and 1.5 is the pitch. If the pitch is not specified, it is assumed to be the standard coarse pitch for that diameter.

In imperial systems, thread size is often described using the American Wire Gauge (AWG) for smaller screws, or by a nominal diameter in inches followed by the number of threads per inch (TPI). For instance, a 1/4-20 UNC thread has a nominal diameter of 1/4 inch and 20 threads per inch using the Unified National Coarse (UNC) thread form.

Understanding gjengestørrelse is essential for selecting the correct mating nut or tapped hole, ensuring a secure and functional connection. Incorrect thread size can lead to a loose fit, damage to the threads, or an inability to assemble the components at all.