Workpieces are clamped on the machine table of a machine tool so that they can be processed. These tables are usually very solid and equipped with T-slots or trapezoidal grooves for receiving T- nuts with fastening threads , which are used for the frictional fastening of tool or workpiece with the help of so-called clamps .
The grooves in the machine table make it possible on the one hand to clamp workpieces directly on the machine table using clamping claws, but on the other hand also to mount clamping aids such as vices or special tools (e.g. lathe chucks ) or devices (e.g. dividing head) .