General Tolerance Iso 2768-mk |top| Review

1‑page summary: General Tolerances — ISO 2768‑m (medium/ks)

Decoding the "mk" Classification

The letters 'm' and 'k' are not arbitrary; they denote specific tolerance classes.

• The first letter (m – Medium): This refers to the tolerance class for linear dimensions (lengths, diameters, radii) and angular measures. The classes range from fine (f) to coarse (c) and very coarse (v). 'm' is the industry-preferred "medium" class.
• The second letter (k – Medium): This refers to the tolerance class for geometric features like flatness and perpendicularity. The geometric classes are H, K, and L. 'k' is the "medium" class for geometry.

Key Insight: Using ISO 2768-mk tells the manufacturer: "Unless a specific tolerance is written on a dimension, assume the 'medium' class for size and the 'medium' class for geometry." general tolerance iso 2768-mk

6.3 Inspection Criteria

• GO/NO-GO gauges – Only required if functional limits are tighter than ISO 2768-mk.
• CMM measurement – Accept part if measured value lies within ± tolerance of the nominal, including gauge uncertainty (rule of 10:1 preferred).

Report: General Tolerances per ISO 2768-mK

Date: October 26, 2023 Subject: Application and Interpretation of ISO 2768-mK The first letter (m – Medium): This refers

What is ISO 2768?

ISO 2768 is an international standard for general tolerances. It is designed for parts where dimensional accuracy is not critical enough to warrant an individual tolerance on every single feature. Key Insight: Using ISO 2768-mk tells the manufacturer:

Instead of cluttering a drawing with ±0.1mm for every hole or slot, you write the standard once in the title block. This tells the workshop: “If no specific tolerance is shown next to a dimension, follow this table.”

The standard is split into two parts:

• ISO 2768-1: Tolerances for linear and angular dimensions (lengths, radii, chamfers, angles).
• ISO 2768-2: Tolerances for geometrical features (flatness, straightness, perpendicularity, symmetry, runout).

2. Breakdown of the Standard

4. Part 2: Geometrical Tolerances (Class "K")

The "K" designation refers to the general geometrical tolerances. It controls features such as straightness, flatness, perpendicularity, and symmetry when specific Geometric Dimensioning and Tolerancing (GD&T) callouts are not used.