For general thermoplastics, the standard typically defaults to unless otherwise specified.
Values are approximate based on standard industry applications of ISO 20457/DIN 16742 .
Open your (or refer to the official chart). Find the nominal size range. Read across to the chosen PT grade. For Category B or C, apply the “additional tolerance” multiplier noted in a footnote (typically +50% for parting lines, +100% for side cores).
Angles are treated differently because the deviation is measured as a length over a given length (mm/m) or directly in degrees/minutes.
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Stop fighting shrinkage. Embrace ISO 20457.
| PT Grade | Description | Typical Application | |----------|-------------|----------------------| | PT1 | Very fine (high precision) | Medical devices, optical components, precision gears | | PT2 | Fine | Consumer electronics, automotive interior trim | | PT3 | Medium | Standard housings, toys, general purpose parts | | PT4 | Coarse | Large panels, containers, parts with thin walls | | PT5 | Very coarse | Very large mouldings (>1000 mm) or warpage-prone materials | | PT6 | Extremely coarse (no tolerance specified) | Reference only for design verification | | PT7 | Up to agreement | For contract-specific requirements |
The free search for an **“iso 20457 tolerance table pdf”” will often yield incomplete versions. The complete official PDF contains more than just the tolerance table. It includes:
: Offers downloadable quality and tolerance templates, including Excel-based CTQ (Critical to Quality) feature tables and 2D note blocks for ISO 20457-TG6. Understanding the Tolerance Groups (TG)
Lower TG numbers (e.g., TG1–TG4) represent high-precision requirements.
Clearly separate Series NW and Series W dimensions on your prints so quality control teams inspect the parts using the correct reference values.
In China, GB/T 4706-2026 (to be implemented August 1, 2026) will integrate with ISO 20457, adding provisions for geometric tolerances and acceptance judgment rules. This alignment further solidifies ISO 20457 as the global benchmark for plastic part tolerancing.
Make sure to verify the authenticity and accuracy of the PDF document before using it for design or manufacturing purposes.
By using the ISO 20457 tolerance table, engineers and manufacturers can:
(e.g., PP, PE, PA66) have high, directional shrinkage.