Workshops know exactly what level of accuracy is expected based on standard workshop capabilities. Structure of the ISO 2768 Standard
ISO 2768-1 applies to dimensions that are produced by metal removal (e.g., CNC machining) or are formed from sheet metal. It provides four distinct tolerance classes, allowing you to select the level of precision that best matches your part's function and your manufacturing capabilities.
serve as the global structural backbone for engineering drawings. It eliminates the need to specify custom tolerances next to every individual dimension.
Most resources simply show you the table. This exclusive guide explains how to use them. iso 2768 general tolerances pdf exclusive
Features with individual tolerances stated take precedence over the general tolerance.
To help you quickly reference the tolerance values according to ISO 2768, we have prepared an exclusive PDF guide. This guide provides a concise overview of the standard, including:
These values apply strictly to the rounding or chamfering of sharp exterior edges. Tolerance Class 0.5 to 3mm (Fine) m (Medium) c (Coarse) v (Very Coarse) 3. Tolerances for Angular Dimensions Workshops know exactly what level of accuracy is
Angles (e.g., a 45° chamfer) have their own rules. The tolerance depends on the length of the shorter side of the angle.
Geometrical tolerances control the shape, orientation, and location of features rather than pure dimensional size. All values below represent total variations in millimetres (mm). 1. Straightness and Flatness
Table based on ISO 2768-1 (Excerpt for linear dimensions, "m" medium class): | Nominal Size Range (mm) | Permissible Deviation (±mm) | |------------------------|-----------------------------| | 0.5 to 3 | 0.1 | | >3 to 6 | 0.1 | | >6 to 30 | 0.2 | | >30 to 120 | 0.3 | | >120 to 400 | 0.5 | serve as the global structural backbone for engineering
The standard dictates that larger nominal dimensions are allowed larger deviations. Below is the data typically compiled into a reference PDF for linear dimensions (values in millimeters): Permissible Deviations for Nominal Size Range (mm) Over 3 to 6 Over 6 to 30 Over 30 to 120 Over 120 to 400 Over 400 to 1000 Over 1000 to 2000 ±0.05plus or minus 0.05 ±0.05plus or minus 0.05 ±0.1plus or minus 0.1 ±0.15plus or minus 0.15 ±0.2plus or minus 0.2 ±0.3plus or minus 0.3 ±0.5plus or minus 0.5 m (Medium) ±0.1plus or minus 0.1 ±0.1plus or minus 0.1 ±0.2plus or minus 0.2 ±0.3plus or minus 0.3 ±0.5plus or minus 0.5 ±0.8plus or minus 0.8 ±1.2plus or minus 1.2 c (Coarse) ±0.2plus or minus 0.2 ±0.3plus or minus 0.3 ±0.5plus or minus 0.5 ±0.8plus or minus 0.8 ±1.2plus or minus 1.2 ±2.0plus or minus 2.0 ±3.0plus or minus 3.0 v (Very Coarse) ±0.5plus or minus 0.5 ±1.0plus or minus 1.0 ±1.5plus or minus 1.5 ±2.5plus or minus 2.5 ±4.0plus or minus 4.0 ±6.0plus or minus 6.0 Angular Dimensions Reference Table
Provide a, example of a drawing note that includes both General Tolerances and surface finish requirements.
If a specific feature on that same drawing requires an incredibly tight fit—like a bearing housing—the designer will manually write a tight tolerance (e.g.,