Tolerance Iso 2768 Mk: Pdf
There are four tolerance classes for linear dimensions:
Focus on "m" (Medium): When you specify "ISO 2768-m," you are telling the shop that a 100mm block can be between 99.8mm and 100.2mm (depending on the nominal size range). Below is the tolerance table for Class "m":
| Nominal Dimension Range (mm) | Tolerance (mm) | | :--- | :--- | | 0.5 up to 3 | ± 0.1 | | >3 up to 6 | ± 0.1 | | >6 up to 30 | ± 0.2 | | >30 up to 120 | ± 0.3 | | >120 up to 400 | ± 0.5 | | >400 up to 1000 | ± 0.8 | | >1000 up to 2000 | ± 1.2 |
Angular dimensions (Class m): For lengths up to 120mm, the tolerance is ± 30 minutes (0.5°). For longer bases, it tightens proportionally. Tolerance Iso 2768 Mk Pdf
| Do NOT use ISO 2768-mK for ... | Reason | |--------------------------------|--------| | Press fits, bearing seats, sliding fits | Needs explicit tolerances (e.g., ISO 286) | | Thread dimensions | Follow thread standards (e.g., ISO 965) | | Welded assemblies | Welding shrinkage invalidates general tolerances | | Plastic or rubber parts | Material flexibility requires tighter/looser control | | High-precision medical, aerospace, or optics | Risk of functional failure |
No. The standard is case-sensitive. You will often see it written as mK (lowercase m, uppercase K) or Mk (rare). Technically, "M" implies the linear class, "K" implies the geometry class. Writing "MK" in all caps is common in file naming but does not change the numerical values.
| Nominal Length of Shorter Side | Tolerance (mm/m or °/') | |--------------------------------|--------------------------| | ≤ 100 mm | ±1° = ±60' | | >100 to 300 mm | ±0° 30' | | >300 to 1000 mm | ±0° 15' | | >1000 to 3000 mm | ±0° 10' | There are four tolerance classes for linear dimensions:
Alternatively: ±0.5 mm per 100 mm length for general angle dimensions.
| Nominal Size Range | Tolerance (mm) | |--------------------|----------------| | 0.5 to 3 | ±0.2 | | >3 to 6 | ±0.5 | | >6 | ±1.0 |
When a drawing title block states:
General tolerances: ISO 2768-mK
It means:
| Nominal Dimension Range (mm) | Tolerance (mm) | | :--- | :--- | | 0.5 up to 3 | ± 0.1 | | >3 up to 6 | ± 0.1 | | >6 up to 30 | ± 0.2 | | >30 up to 120 | ± 0.3 | | >120 up to 400 | ± 0.5 | | >400 up to 1000 | ± 0.8 | | >1000 up to 2000 | ± 1.2 | Focus on "m" (Medium): When you specify "ISO
Example: A shaft length of 50mm with no individual tolerance is acceptable between 49.7mm and 50.3mm.