Formschlussverbindungen

Formschlussverbindung, commonly called form-fit connection, is a principle in mechanical engineering where two components are interlocked by their geometric shapes so that relative movement is constrained by the mating geometry rather than by friction or external clamping forces. The connection relies on the physical interlock of the parts, producing restraint in the intended directions through shape alone.

Principle: The components are machined so that their mating profiles fit with little or no clearance. When assembled, the geometry itself prevents separation or sliding along defined directions. This is contrasted with Kraftschluss, where loads are resisted primarily by friction, clamping, or elastic deformation rather than by interlocking shape.

Examples: Traditional dovetail joints used in woodworking and metalwork, tongue-and-groove connections, and other interlocking profiles used in gears, cam mechanisms, slides, and fixtures. In these cases, the geometry ensures positional stability and alignment before any additional clamping or fastening.

Advantages: Form-fit assemblies often provide precise location and high shear resistance without relying on friction coefficients. They can offer good repeatability, straightforward initial alignment, and predictable behavior under the intended load paths.

Limitations: The approach demands tight manufacturing tolerances and accurate assembly. It can be difficult or damaging to disassemble, and its effectiveness is highly direction-dependent and sensitive to temperature-related expansion. Not all loads or service conditions are suitable for form-fit connections, especially where adaptivity or easy disassembly is required.

Applications: Locating and guiding components in machinery, fixtures and jigs, tool holders, dovetail slides, and other assemblies where reliable, repeatable alignment is essential.

See also: Kraftschluss, Formschluss.