| Part | Title | Purpose | |------|-------|---------| | | General tolerances for linear and angular dimensions | Defines tolerance classes (f, m, c, v) for sizes, radii, chamfers, and angles | | ISO 2768-2 | General tolerances for geometrical features | Defines tolerance classes (H, K, L) for straightness, flatness, parallelism, perpendicularity, symmetry, runout |
GENERAL TOLERANCES: ISO 2768-MK-E Alternatively:
| Nominal Range (mm) | Straightness / Flatness (± mm) | Perpendicularity (± mm) | |--------------------|--------------------------------|-------------------------| | ≤10 | 0.05 | 0.1 | | >10 to 30 | 0.1 | 0.2 | | >30 to 100 | 0.2 | 0.3 | | >100 to 300 | 0.3 | 0.4 | | >300 to 1000 | 0.4 | 0.5 | | >1000 to 3000 | 0.5 | 0.6 | iso 2768-mk-e
– Same values as perpendicularity. Circular runout – 0.2 mm (class K). Total runout – Not defined; must be specified individually. Example: A 200 mm long machined surface without a flatness callout → allowed flatness deviation = 0.3 mm. 3.3 "E" – External Radii & Chamfer Heights (ISO 2768-1 Annex A) The "E" instructs that tolerances for external radii and chamfer heights follow the same "M" class limits as linear dimensions, but applied to the radius or chamfer size.
These values apply per 100 mm of length. For longer lengths, the tolerance is prorated but limited by the maximum deviation. | Part | Title | Purpose | |------|-------|---------|
| Tolerance Class | Straightness & Flatness (mm per 100 mm) | Perpendicularity & Symmetry (mm per 100 mm) | Runout (mm) | |----------------|------------------------------------------|----------------------------------------------|--------------| | | 0.2 | 0.5 | 0.2 |
| Feature Type | Rule | |--------------|------| | Length, width, height | ± mm from "M" linear table | | Hole diameter | Not covered (size tolerance must be given individually unless it's a general dimension) | | Hole position | Covered by "K" position tolerance (0.5 mm per 100 mm) | | Flatness of a surface | 0.2 mm per 100 mm (class K) | | Perpendicularity of a shoulder | 0.5 mm per 100 mm (class K) | | External fillet radius R5 | ±1.0 mm (since 5 mm is in >3–6 range, "E") | | Chamfer C2 | ±0.5 mm (from "E" table) | Example: A 200 mm long machined surface without
When a designer writes ISO 2768-MK-E in the title block or general notes of a drawing, it instructs the manufacturer that must conform to the specific limits defined by this standard.