Fehllage

Fehllage is a German technical term used to describe the misalignment or incorrect positioning of a component within a larger system relative to a designated reference. It generally encompasses both translational misalignment (offsets) and angular misalignment (tilt), and can occur in static assemblies or during operation.

Etymology and usage: The word combines Fehl, meaning fault or error, with Lage, meaning position or orientation. In engineering, construction, optics, electronics, and related fields, Fehllage is used to indicate deviations from the intended spatial relationship between parts, such as shafts, bearings, lenses, or fastened joints.

Causes: Fehllage arises from manufacturing tolerances, improper or incomplete assembly, wear and tear, thermal expansion, mechanical deformation, or dynamic loading. Measurement errors during installation can also conceal or introduce misalignment.

Detection and measurement: Detection relies on metrology and alignment methods, including dial indicators, laser trackers, optical autocollimators, and coordinate measuring machines. Operating observations, such as unusual vibration, noises, or reduced performance, also signal possible Fehllage.

Consequences and mitigation: Fehllage can cause increased wear, higher energy consumption, reduced accuracy, noise, leakage, or structural stress. Mitigation involves tighter tolerances, precise installation procedures, adjustable mounts or shims, regular calibration, and thermal compensation or redesign to minimize sensitivity to misalignment.

Examples and contexts: In automotive maintenance, wheel or suspension misalignment is a practical form of Fehllage. In optical or electronic systems, misaligned lenses or components degrade system performance. The term communicates the need to verify and correct relative positioning to restore proper function.