This class provides permissible deviations based on the nominal size of the dimension. Nominal Length Range (mm) Tolerance (± 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 over 2000 to 4000 ISO 2768-1 Tolerance Chart ISO 2768-2: Geometrical Tolerances (Class K)
: The choice of tolerance class should always be guided by the functional requirements of the part. In some cases, even medium tolerance classes might be too loose.
Limits how flat a surface must be or how straight an axis must be.
The designation is split into two distinct parts, covering different aspects of the physical part:
Key Takeaway: If a part has a 1mm warp on a 100mm face, it may fail the 'K' class requirement (which usually allows far less, such as 0.2mm). Why Use ISO 2768-mK? general tolerance iso 2768-mk
This part of the standard covers lengths, diameters, radii, and angles. The "m" (medium) class is the industry's "sweet spot," balancing functional accuracy with cost-effective manufacturing. Linear Dimension Tolerances (mm)
The designation indicates a specific combination of tolerance classes:
ISO 2768 is an international standard for . It is designed for parts where dimensional accuracy is not critical enough to warrant an individual tolerance on every single feature.
Inspection teams know exactly which thresholds to test against without interpreting ambiguous design intents. This class provides permissible deviations based on the
Angular tolerances in the "m" class are determined based on the length of the shorter leg of the angle in question: Length of Shorter Leg (mm) Tolerance Class (Medium) Up to 10 Over 10 to 50 Over 50 to 120 Over 120 to 400 Over 400 Part 2: Geometrical Tolerances (The "k" Class)
ISO 2768 Part 1 divides tolerances into four classes: (fine), m (medium), c (coarse), and v (very coarse). The "m" class balances manufacturing cost with functional precision, making it the most common choice for general CNC machining and sheet metal fabrication.
For Class K, the general tolerance for is fixed at 0.2 mm .
ISO 2768-2 covers Geometric Dimensioning and Tolerancing (GD&T) features. It simplifies drawings by eliminating the need to individualise symbols for straightness, flatness, and perpendicularity unless a critical fit demands it. Limits how flat a surface must be or
ISO 2768-MK is a widely used international standard for general tolerances. It was published by the International Organization for Standardization (ISO) and provides a framework for defining general tolerances for linear and angular dimensions.
The notation "ISO 2768-mK" references two distinct parts of the ISO 2768 standard, applying different classes to different types of measurements.
The use of general tolerances like those defined in ISO 2768-MK offers several advantages:
