| Nominal Size Range (mm) | Fine (f) Tolerance (± mm) | Medium (m) Tolerance (± mm) | Coarse (c) Tolerance (± mm) | | :--- | :--- | :--- | :--- | | 0.5 up to 3 | 0.05 | 0.1 | 0.2 | | 3 up to 6 | 0.1 | 0.2 | 0.5 | | 6 up to 30 | 0.2 | 0.5 | 1.0 | | 30 up to 120 | 0.3 | 0.8 | 1.5 | | 120 up to 400 | 0.5 | 1.2 | 2.5 | | 400 up to 1000 | 0.8 | 2.0 | 4.0 | | 1000 up to 2000 | 1.2 | 3.0 | 6.0 | | 2000 up to 4000 | 2.0 | 5.0 | 10.0 |
The faded PDF had been the beginning, but it was the people who turned tolerances into workmanship and standards into community. And whenever a stranger asked about the framed sheet, Ana would say simply: "It's the promise we make to each other—that things will fit, function, and last."
Unlike metal fabrication, plastic injection molding relies on raw material behavior, part geometry, tool construction, and process variables. ISO 20457 categorizes these dynamics into nine designated , representing a spectrum from extreme high-precision to general-purpose molding. iso 20457 tolerance table pdf
The standard is part of the broader ISO GPS (Geometrical Product Specifications) system. The GPS "matrix model" provides a set of rules and tools for the specification of geometry, and ISO 20457 is fully integrated within this framework.
: These range from high precision (TG1) to normal production (TG9). For standard thermoplastics in injection molding, is a frequently used baseline for general tolerances. Dimensional Categories | Nominal Size Range (mm) | Fine (f)
The standard, which replaced DIN 16742, defines the tolerances and acceptance conditions for plastic molded parts. It uses Tolerance Groups (TG) to classify accuracy based on material properties and manufacturing processes. Key Tolerance Group: TG6
ISO 20457 is an indispensable tool for anyone involved in the design, molding, or sourcing of plastic parts. By using its tolerance tables and systematic approach, you can avoid costly rework, ensure proper assembly, and achieve reliable quality. The shift from experience-based guesswork to a structured system like ISO 20457 is a foundational step in professionalizing plastic parts engineering. The standard is part of the broader ISO
To get the :
| Nominal Size (mm) | Fine Tolerance (approx.) | Medium Tolerance (approx.) | Coarse Tolerance (approx.) | | :--- | :--- | :--- | :--- | | up to 10 mm | ±0.05 mm | ±0.10 mm | ±0.20 mm | | >10 mm up to 50 mm | ±0.10 mm | ±0.20 mm | ±0.30–0.40 mm |
Many reputable injection molders provide tailored PDFs or links, often referencing DIN ISO 20457, which is functionally the same. Steps to Apply the Table: