Iso 20457 Tolerance Table Pdf
ISO 20457:2018 – “Geometrical product specifications (GPS) — Tolerancing of moulded parts”
It applies specifically to plastic and rubber injection moulded parts, die castings, and similar processes. Unlike general machining tolerances, moulded parts have unique shrinkage, warpage, and draft angle requirements.
Let’s walk through a real-world example to solidify your understanding of the ISO 20457 tolerance table PDF.
Scenario: A company is designing a mounting bracket for an electric motor. The bracket is a sheet metal part (2mm thick, 200mm long). The motor has a shaft that aligns to a hole.
Result: The machinist reads the PDF, applies the correct deviations, and the bracket is cheap to produce (not over-toleranced) but still fits the motor.
The core of the standard lies in its tabulated data, organized into four tolerance classes: fine (f), medium (m), coarse (c), and very coarse (v). The tables are not a single monolithic grid but are separated by the type of geometrical characteristic. The key tables within the ISO 20457 PDF document typically include:
Each table uses the four tolerance classes, allowing a designer to scale the precision to the functional needs of the part.
The keyword **“iso 20457 tolerance table pdf”” is widely searched, but caution is required. Many websites offer “preview” tables that are incomplete or contain typographical errors. As of 2025, the official standard is copyrighted by ISO (Geneva) and national bodies like ANSI, BSI, DIN, and AFNOR.
The tolerance tables are split based on what is being measured. The two most common tables you will encounter are:
The tolerances vary depending on the material, as different plastics shrink and mold differently. The standard generally divides materials into groups: iso 20457 tolerance table pdf
Purpose and scope
Key structure of the tolerance table (typical elements)
Interpretation nuances
Practical application guidance
Common pitfalls
When to consult the PDF/standard directly
Concise recommendation
The ISO 20457 standard (which succeeded DIN 16742) provides a standardized framework for tolerances and acceptance conditions for plastic molded parts. It defines tolerance groups (TG) ranging from TG1 to TG9, where lower numbers indicate higher precision. For many standard industrial thermoplastics, TG6 is the commonly used baseline for general tolerances. Key Tolerance Tables and Documents
Because ISO 20457 is a copyrighted standard, full official tables are typically accessed through authorized distributors or summarized by manufacturers. You can find detailed overviews and downloadable PDF guides at the following sources: Result: The machinist reads the PDF, applies the
PolTolerances Guide (Makrolar): A comprehensive 28-page PDF that includes detailed tolerance tables, explanations of dimensional deviations, and the relationship between ISO 20457 and DIN 16742.
OKW Gehäusesysteme Tolerance Overview: Provides a concise technical data sheet focusing on TG6 tolerances for various nominal dimensions.
ISO Official Store: The definitive source to purchase and download the official ISO 20457:2018 PDF for full compliance.
Super Ingenuity Template Library: 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)
The tolerance applied to a part depends on both the chosen Tolerance Group and the Nominal Dimension (the size of the feature). Nominal Dimension (mm) TG4 (High Precision) TG6 (Standard/Technical) TG8 (General Purpose) > 10 to 18 > 18 to 30
Note: These values are typical approximations for linear dimensions; refer to the official standard for the full matrix covering all dimensions and specific material groups. Selection Process
ISO 20457:2018 is the primary international standard for determining manufacturing tolerances and acceptance conditions for non-porous plastic molded parts. It replaces the older DIN 16742 standard and provides a systematic way to calculate achievable tolerances based on material properties and manufacturing processes. Unlike metal machining standards, ISO 20457 accounts for the unique behavior of plastics, such as mold shrinkage and environmental sensitivity. Key Components of ISO 20457
The standard uses a tiered system to assign tolerance groups (TG) based on the material's complexity and the required precision:
standard (which replaced the older DIN 16901) provides a comprehensive system for determining manufacturing tolerances for plastic molded parts. It classifies tolerances into Tolerance Groups (TG) Each table uses the four tolerance classes, allowing
based on material properties (such as shrinkage and stiffness) and the manufacturing process used. www.makrolar.eu Tolerance Tables Overview
While the full standard is a paid document, several engineering resources provide summarized tables for common applications. Tolerance Groups (TG1–TG9)
: 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
: Tolerances are assigned based on the nominal dimension of the part (e.g., < 1mm, 1–6mm, 6–30mm, etc.). Material Influence
: High-shrinkage materials (like POM or PA6) typically require larger tolerance values compared to low-shrinkage materials (like ABS or PC). OKW Gehäusesysteme Reference Documents & PDF Guides
You can find detailed summaries and excerpts of the tolerance tables in the following resources: Engineering Guides PolTolerances Guide
provides a detailed 18-page technical overview of ISO 20457/DIN 16742, explaining how to calculate and apply these values. Industry Application OKW Enclosures provides a Tolerances PDF that specifies how they apply to their thermoplastic injection molded parts. Standard Samples iTeh Standards Sample PDF of ISO 20457:2018
which includes the first few pages and Table 8 (General Tolerances). Detailed Overviews
: For a more visual breakdown of the material categories and tolerance groups, Online Documentation on understanding plastic part tolerances. OKW Gehäusesysteme TOLERANCES