Iso 2768-mk-e Best -

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.

| 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 |

| 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 | iso 2768-mk-e

1. Introduction ISO 2768-MK-E is a combined shorthand notation used on engineering drawings and technical documents. It references three parts of the ISO 2768 standard, which specifies default tolerances for linear dimensions, angular dimensions, geometrical features (form, orientation, location, and runout), and the indication of "E" for general external radius and chamfer dimensions.

| 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) | When a designer writes ISO 2768-MK-E in the

| Tolerance Class | Straightness & Flatness (mm per 100 mm) | Perpendicularity & Symmetry (mm per 100 mm) | Runout (mm) | |----------------|------------------------------------------|----------------------------------------------|--------------| | | 0.2 | 0.5 | 0.2 |

These values apply per 100 mm of length. For longer lengths, the tolerance is prorated but limited by the maximum deviation. It references three parts of the ISO 2768

For production shops, understanding this shorthand reduces errors and clarifies expectations. For designers, using it correctly (and knowing its limits) produces clear, manufacturable drawings without over-tolerancing.