For straightness tolerances, the relevant line length is considered. For flatness, the larger side length of the surface (or the diameter of a circular surface) is used.
The story within the PDF revealed a legendary project from the late 80s: The Phoenix Probe. The engineers had simplified their drawings by using ISO 2768-m for linear dimensions, assuming the medium class would be enough. But they forgot Part 2—the geometrical tolerances for things like straightness and symmetry.
ISO 2768 was first published in 1989 by the International Organization for Standardization (ISO) to address inconsistencies in tolerance definitions across different countries and regions. As industries became more globalized, the need for a unified specification became critical to ensure part interchangeability and compatibility in international trade.
This article is provided for informational purposes only and does not constitute legal advice. All tolerance values presented are based on ISO 2768-1:1989 and ISO 2768-2:1989. For official certification or legal use, always consult and purchase the complete standards from authorized distributors.
This part deals with (size) for features like lengths, diameters, and angles. It applies to machined parts and parts formed from sheet metal. 2. ISO 2768-2: Geometrical Tolerances iso 2768 general tolerances pdf exclusive
It indicates tolerances for linear/angular dimensions and Class K tolerances for geometric features. Example 2: ISO 2768-fH
Source: 13†L19-L20
ISO 2768-1 applies to dimensions that are produced by metal removal (e.g., CNC machining) or are formed from sheet metal. It provides four distinct tolerance classes, allowing you to select the level of precision that best matches your part's function and your manufacturing capabilities.
The standard was originally published in 1989, canceling and replacing the older ISO 2768:1973. It is divided into two distinct but complementary parts: For straightness tolerances, the relevant line length is
Indicates linear dimensions and High (H) geometric precision. Typically reserved for high-end CNC machining or aerospace components. Why You Need an Exclusive ISO 2768 PDF Download
Issued by the International Organization for Standardization (ISO), ISO 2768 is designed to simplify engineering drawings. Instead of listing tolerances for every single dimension—which would make blueprints cluttered and unreadable—designers can simply state on the drawing: "General tolerances according to ISO 2768-[Class]" . The standard is divided into two primary parts: 1. ISO 2768-1: Linear and Angular Dimensions
Elias closed the tablet and looked at the CNC machines waiting on the floor. "Now, let’s go cut some metal. And Leo? Make sure you check the chamfer heights for those broken edges—ISO 2768-1 is very specific about those.". General Tolerance - ISO 2768 1 & 2 - ZEISS Quality Forum
The "Exclusive PDF" wasn't a magic spell; it was a testament to the global standard that allowed a part designed in Sweden to fit perfectly into a machine built in Singapore. It was the quiet, invisible backbone of the modern world. The engineers had simplified their drawings by using
ISO 2768-mK indicates a drawing utilizing medium linear tolerances (m) and medium geometric tolerances (K).
Suitable for components where high precision is not critical.
The standard provides a set of tolerance classes, each with its own set of tolerance values, which can be used to specify the acceptable limits of variation for a particular feature.