In manufacturing, "close enough" is rarely acceptable. Tolerance tables are the translation layer between a designer's intent and a machinist's execution. ISO 20457 tolerance tables are particularly important for several reasons:
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.
As we move toward Industry 4.0 and Model-Based Definition (MBD), the ISO 20457 tolerance table PDF is evolving into a machine-readable format. Future revisions may come as XML or JSON files that CAD systems read automatically. However, for the next decade, the PDF will remain the universal backup—the human-readable master key.
To get the official ISO 20457 tolerance table PDF:
Would you also like a comparison table between ISO 20457 and the older DIN 16901, or a sample drawing note for applying these tolerances?
Understanding the ISO 20457 Tolerance Table The ISO 20457 standard, which officially replaced the older German standard DIN 16742, is the global benchmark for specifying dimensional and geometrical tolerances of plastic molded parts.
Whether using injection molding, compression molding, or rotational molding, achieving high precision in plastics requires accounting for unique polymer characteristics like shrinkage, moisture absorption, and thermal expansion. 🛠️ The Purpose of ISO 20457
In the manufacturing of plastic parts, applying standard metal tolerances (like ISO 2768) is not practical. Plastics behave differently during and after cooling.
The ISO 20457 Standard defines acceptable manufacturing deviations to:
Establish realistic limits for part sizes based on manufacturing effort and tooling.
Prevent over-specification, which leads to unnecessarily expensive molds and high scrap rates.
Set uniform general tolerances when no individual tolerance is specified directly on the drawing. iso 20457 tolerance table pdf
📐 Tolerance Class TG6: The Most Common Injection Molding Standard TOLERANCES
The ISO 20457:2018 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
TG6 is a common baseline for thermoplastic injection molding. Below is a summary of the general tolerances for this group: Nominal Range (mm) Tool-Specific (W) (± mm) Non-Tool-Specific (NW) (± mm) 1 to 3 3 to 6 6 to 10 10 to 18 18 to 30 30 to 50 50 to 80 80 to 120 Source: Derived from OKW-Tolerances-en (PDF). Tolerance Determination Process
ISO 20457 (and its German equivalent DIN 16742) is the definitive global standard for manufacturing tolerances and acceptance conditions of plastic molded parts
. It replaced older standards like ISO 8062 to better account for the unique properties of plastics—such as shrinkage and thermal expansion—which differ significantly from metals. www.makrolar.eu Core Function of ISO 20457
The standard provides a systematic way to determine achievable tolerances based on the combination of material properties, molding processes, and part geometry. It primarily covers: Dimensional Tolerances : General tolerances for linear and angular dimensions. Geometrical Tolerances : Surface profile and position deviations. Acceptance Conditions : Specific environment requirements, such as measuring at 23 raised to the composed with power cap C 50% relative humidity , to ensure consistency across different facilities. ISO - International Organization for Standardization Tolerance Groups (TG) Breakdown The ISO 20457 tolerance table is organized into Tolerance Groups (TG) , typically ranging from TG1 to TG9 . These groups correlate to the ISO 286 IT grades used in metal machining. ResearchGate ISO 20457:2018(en), Plastics moulded parts
Title: Download ISO 20457 Tolerance Table PDF for Precision Engineering
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.
What is ISO 20457? ISO 20457 is a widely adopted standard that defines a set of tolerances for various features, including:
The standard provides a framework for specifying tolerances that balance the need for precision with the practical limitations of manufacturing processes.
ISO 20457 Tolerance Table PDF: The ISO 20457 tolerance table provides a detailed list of tolerances for various features, including:
By using the ISO 20457 tolerance table, engineers and manufacturers can: In manufacturing, "close enough" is rarely acceptable
Benefits of Using ISO 20457:
Download ISO 20457 Tolerance Table PDF: You can download the ISO 20457 tolerance table PDF from various sources, including:
Make sure to verify the authenticity and accuracy of the PDF document before using it for design or manufacturing purposes.
Conclusion: The ISO 20457 tolerance table PDF is a valuable resource for engineers, manufacturers, and designers who need to specify tolerances for linear and angular dimensions, as well as geometric tolerances. By using this standard, you can ensure precision, accuracy, and interchangeability of parts and components, ultimately leading to improved product quality and reliability.
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)
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 Each table uses the four tolerance classes, allowing
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
ISO 20457 (and its German equivalent DIN 16742) is the international standard for dimensional and geometrical tolerances of plastic molded parts. It replaces older standards like DIN 16901 to provide a more consistent framework for injection molding and related processes. Key Tolerance Tables & TG Groups
The standard classifies tolerances into Tolerance Groups (TG), typically ranging from TG1 to TG9. TG6 is the most common baseline for commercial plastic parts. Nominal Dimension (mm) TG4 (Precision) TG6 (General) TG8 (Coarse)
Values are approximate based on standard industry applications of ISO 20457/DIN 16742. How to Choose a Tolerance Group
Choosing the right TG depends on the material's shrinkage behavior and the part's functional requirements.
Material Family: Amorphous resins (e.g., ABS, PC) have lower shrinkage and can often achieve TG4 or TG5. Semi-crystalline resins (e.g., PA66, POM) have higher shrinkage and usually require TG6 or higher.
Production Difficulty: Tighter groups (TG1–TG3) are rarely used as they significantly increase mold costs and scrap rates.
Baseline Standard: Most engineering components default to TG6 unless specified otherwise for critical fitments like snap-fits. PDF Resources & Technical Guides
You can access detailed guides and full tolerance tables through these technical document repositories:
PolTolerances Guide: A detailed 4-page overview of ISO 20457 and DIN 16742 including classification tables.
Standard Preview: An official abstract and sample pages of the ISO 20457:2018 Standard.
Engineering Guidelines: Practical application guides from manufacturers like OKW Gehäusesysteme showing how they apply TG6 to their thermoplastic products. PolTolerances en ISO-20457 (DIN 16742) - Scribd
| Feature | ISO 2768-1 | ISO 20457 | |-------------------------|--------------------------------|--------------------------------------| | Applicable to | Machined parts | Moulded parts (plastic, rubber, die cast) | | Has a simple table? | Yes (f, m, c, v classes) | No — calculation-based | | Considers shrinkage? | No | Yes | | Draft angles included? | No | Yes (separate section) |