General Tolerance – ISO 2768 1&2 Standard

ISO 2768 primarily applies to parts produced through machining or material removal. 
This standard should be followed for part sizes with no marked tolerance ranges. 
Please keep in mind that all tolerance limits are given in millimetres.

Part 1: General Tolerances ISO 2768-1

ISO 2768-1 specifies general tolerances in four tolerance classes (f – fine, m – medium, c – coarse, v – very coarse) in order to simplify drawing indications. It is applicable to linear and angular dimensions such as external sizes, internal sizes, step sizes, diameters, radii, distances, external radii, and broken edge chamfer heights.
 
If ISO 2768 general tolerances apply, ISO 2768 followed by the tolerance class (Ex: ISO 2768-m) must be indicated in or near the title block.
 

The tolerance table corresponding to the four class precision levels is shown below; you can select the most appropriate one based on your machining capabilities and design requirements.

Table 1 - Linear Dimensions

Permissible deviations in mm for ranges in nominal lengths Tolerance Class Designation (Description)
f (fine) m (medium) c (coarse) v (very coarse)
0.5 up to 3 ±0.05 ±0.1 ±0.2
over 3 up to 6 ±0.05 ±0.1 ±0.3 ±0.5
over 6 up to 30 ±0.1 ±0.2 ±0.5 ±1.0
over 30 up to 120 ±0.15 ±0.3 ±0.8 ±1.5
over 120 up to 400 ±0.2 ±0.5 ±1.2 ±2.5
over 400 up to 1000 ±0.3 ±0.8 ±2.0 ±4.0
over 1000 up to 2000 ±0.5 ±1.2 ±3.0 ±6.0
over 2000 up to 4000 ±2.0 ±4.0 ±8.0

For nominal sizes below 0.5 mm, the deviations shall be indicated adjacent to the relevant nominal size(s).

Table 2 - External Radii and Chamfer Heights

Permissible deviations in mm for ranges in nominal lengthsTolerance Class Designation (Description)
f (fine)m (medium)c (coarse)v (very coarse)
0.5 up to 3±02±0.2±0.4±0.4
over 3 up to 6±0.5±0.5±1.0±1.0
over 6±1.0±1.0±2.0±2.0

For nominal sizes below 0.5 mm, the deviations shall be indicated adjacent to the relevant nominal size(s).

Table 3 - Angular Dimensions

Permissible deviations in mm for ranges in nominal lengthsTolerance Class Designation (Description)
f (fine)m (medium)c (coarse)v (very coarse)
up to 10±1º±1º±1º30′±3º
over 10 up to 50±0º30′±0º30′±1º±2º
over 50 up to 120±0º20′±0º20′±0º30′±1º
over 120 up to 400±0º10′±0º10′±0º15′±0º30′
over 400±0º5′±0º5′±0º10′±0º20′

Part 2. General Tolerances ISO 2768-2

ISO 2768-2 is for simplifying drawing and fixing general tolerances in three tolerance classes (H, K, and L), with this part including General Geometrical Tolerances for flatness and straightness, cylindricity, and circularity. Check out the tolerance chart below:

Table 4 - General Tolerances on Straightness and Flatness

Ranges of nominal lengths in mmTolerance Class
HKL
up to 100.020.050.1
above 10 to 300.050.10.2
above 30 to 1000.10.20.4
above 100 to 3000.20.40.8
above 300 to 10000.30.61.2
above 1000 to 30000.40.81.6

Table 5 - General Tolerances on Perpendicularity

Ranges of nominal lengths in mmTolerance Class
HKL
up to 1000.20.40.6
above 100 to 3000.30.61.0
above 300 to 10000.40.81.5
above 1000 to 30000.51.02.0

Table 6 - General Tolerances on Symmetry

Ranges of nominal lengths in mmTolerance Class
HKL
up to 1000.50.60.6
above 100 to 3000.50.61.0
above 300 to 10000.50.81.5
above 1000 to 30000.51.02.0

Table 7 - General Tolerances on Circular Run-Out

Ranges of nominal lengths in mmTolerance Class
HKL
0.10.20.5

The Latest Revision PDF of ISO 2768

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