Positive fit

Positive locking is the fixing of the relative movement of components by means of design details in order to block movement in certain directions. Examples of this are permanent snap-fit connections, tongue-and-groove joints, bayonet fittings and rivets. The movable connection in insert moulding also falls under this category.

In contrast, the screw thread does not form a positive lock, but a self-locking frictional connection, i.e. a force fit. When two components are screwed together, however, the connection of the component without a thread is achieved by positive locking.