Would you like a printable one‑page PDF with the exact ISO table values filled in (I will include the numeric tables from the standard)?
The callout consists of two parts that cover different aspects of the part's design:
Controls the alignment of features relative to a central axis.
| Nominal Length Range (mm) | Permissible Deviation ('K' Class, mm) | | :--- | :--- | | up to 10 | 0.05 | | over 10 up to 30 | 0.10 | | over 30 up to 100 | 0.20 | | over 100 up to 300 | 0.40 | | over 300 up to 1000 | 0.60 | | over 1000 up to 3000 | 0.80 |
: Refers to ISO 2768-2 , which defines geometric tolerances such as flatness, straightness, and perpendicularity. When to Use This Callout general tolerance iso 2768-mk
Among these, is the most globally recognized standard. When a drawing features the designation ISO 2768-mk , it establishes a universal baseline for acceptable variations in both linear dimensions and geometrical features. Decoding the Designation: What Does "m" and "k" Mean?
The specific values are defined by tables. As a rule, the permissible deviation increases with the size of the part being measured.
Using this standard streamlines the design-to-manufacturing workflow, lowers production costs, and ensures high-quality part interchangeability. 1. Structure of the Designation
The specific designation is one of the most commonly used general tolerance classes in precision machining, CNC milling, and turning. It establishes a baseline of acceptable accuracy for dimensions that do not require specialized high-precision tolerances. Breaking Down the Designation: What Does "mK" Mean? Would you like a printable one‑page PDF with
For class "k", the general tolerance for symmetry is 0.6 mm across all size ranges.
Inspection teams can quickly reference a single standard matrix to verify part compliance, accelerating the quality assurance workflow.
This report is designed as a practical guide for engineers, drafters, and quality control inspectors to understand, apply, and inspect tolerances based on this standard.
Press fits, slide fits, and bearing journals require tolerances far tighter than the ±0.1 mm to ±0.3 mm provided by the "m" class. These always require explicit limit dimensions or GD&T (Geometric Dimensioning and Tolerancing) callouts. When to Use This Callout Among these, is
The designation consists of two lowercase and uppercase letters, each representing a specific tolerance class from a different part of the ISO 2768 standard:
Understanding ISO 2768-mK: The Standard for General Tolerances in Manufacturing
If a single specific feature requires a tighter tolerance (e.g., a press-fit bearing shaft that needs a ±0.01 mm window), the engineer simply overrides the general standard by typing that specific tolerance directly next to the dimension on the layout.