Iso 20457 Tolerance Table Pdf
ISO 20457:2018 standard (often referenced alongside ) defines the tolerances and acceptance conditions for plastic molded parts. It replaces the older DIN 16742 standard to provide a global unified guide for designers and manufacturers to manage the unique dimensional, shape, and positional deviations inherent in polymer cooling and shrinkage. www.makrolar.eu Key Components of ISO 20457 Tolerance Groups (TG):
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Tolerance Grade (TGx): Specifying the exact group (e.g., TG6). The official ISO website ( www
Introduction: ISO 20457 is an international standard that specifies tolerances for linear and angular dimensions, as well as geometric tolerances, for features on parts and products. The standard provides a comprehensive tolerance table that engineers and manufacturers can use to ensure precision and accuracy in their designs and manufacturing processes. IHS Standards Store
A practical summary of the TG6 group values used for injection molding is available through technical resources like OKW Tolerances ISO Official Standard: The full official text and thumbnails for ISO 20457:2018 are available on the ISO Online Browsing Platform Templates & Snippets:
The Purpose of General Tolerances
Before examining the tables, it is necessary to understand why ISO 20457 exists. Older national standards (such as DIN 7168 or ISO 2768) served the same purpose: to define default tolerances for dimensions and geometry that are not individually specified on a drawing. ISO 20457 supersedes and harmonizes these earlier standards into a single GPS framework. The standard allows a designer to state in a title block or note: “General tolerances according to ISO 20457 – medium class.” This single line replaces dozens of individual tolerance notes, reducing drawing clutter and ensuring that simple features—like a chamfer, a non-critical length, or a flat surface—receive a reasonable, shop-floor-friendly tolerance without explicit callouts.
- The official ISO website (www.iso.org)
- Online libraries and databases (e.g., IHS Standards Store, Techstreet)
- Engineering and manufacturing websites and forums