Use a digital micrometer (not calipers). Calipers have an error of ±0.025mm—too large for confident judgment. The 75-micron band requires a resolution of 0.001mm.
for a shaft (lowercase letters represent external features). The "h" designation indicates that the upper limit of the part's size is exactly the nominal dimension (the zero line), meaning the tolerance zone is entirely on the "minus" side. International Tolerance (IT) grade 6h11 tolerance
To understand 6h11, you must break the designation into its three core components: Use a digital micrometer (not calipers)
To decode 6h11, you must understand the ISO 286 system (formerly DIN 7160/7161). The code is broken into three parts: , the tolerance class (h) , and the tolerance grade (11) . for a shaft (lowercase letters represent external features)
Because 6h11 is an "h" class tolerance, the part will always be smaller than or equal to the nominal size—it can never be larger. For a 6mm nominal size, the limits are: 6.000 mm (0 deviation). Lower Limit: 5.925 mm (-0.075 mm). Total Tolerance Zone: 0.075 mm (75 micrometers). Nominal Size (mm) Upper Limit (mm) Lower Limit (mm) Tolerance (μm) Over 3 to 6 Over 6 to 10 Over 10 to 18 Data source: Fuller Fasteners ISO Tolerance Chart . Typical Applications
Despite its versatility, 6h11 is wrong for many applications.
: Standard raw materials for machining that don't require high-precision finishing.