Geometrical product specifications (GPS) – ISO code system for tolerances on linear sizes (Basis of tolerances and deviations).
In mechanical engineering and manufacturing, defining every single dimension with a specific tolerance is impractical and would clutter technical drawings. To solve this, standards bodies have established "General Tolerances" to apply to dimensions that do not have individual tolerance specifications. din 7161 pdf
The standard is titled "ISO system of limits and fits; Gauges for plain cylindrical workpieces; Gauge dimensions and permissible errors for workpieces up to 500 mm nominal size." [1] Core Features of DIN 7161 Geometrical product specifications (GPS) – ISO code system
The number following the letter defines the size of the tolerance window (the accuracy). Lower numbers mean tighter tolerances: The standard is titled "ISO system of limits
: While it was a German (DIN) standard, it was designed to align with international ISO recommendations (specifically ISO/R286-1962 at the time) to facilitate global trade. The Legacy and Transition
The shaft is always larger than the hole, requiring force, heat, or cold contraction to assemble. Gears on shafts, bushings, permanent assemblies. H7/p6 or H7/s6 The Transition: DIN 7161 vs. ISO 286