Prüflehren

Prüflehre, plural Prüflehren, is a measuring tool used in manufacturing and metrology to verify whether a component conforms to specified dimensions and geometries. They serve as quick, reliable checks during production and final inspection and are designed to reproduce a defined size or profile with tight tolerances. Prüflehren can be used alone or with other measuring instruments such as micrometers, calipers, or coordinate measuring machines. Some function as go/no-go gauges, allowing parts within tolerance to pass while rejecting those outside it.

Common forms include straight gauges for length checks, stepped gauges for checking hole depths or distances between features, and contour or form gauges for verifying shapes and profiles. Angle gauges are also used to verify angular features. The choice depends on the feature to inspect and the production process. Materials are usually hardened tool steel, stainless steel, or carbide; many are ground and finished to exact tolerances and are calibrated against reference standards.

Calibration and traceability are important: Prüflehren are typically calibrated against national or international standards, with certificates documenting accuracy. Regular checks and proper handling extend their life and maintain measurement reliability. In quality control, Prüflehren complement direct measurements by enabling fast, repeatable go/no-go decisions and, when needed, providing a routine reference for more detailed metrology. They are common in machining, toolmaking, automotive, and assembly industries.