Iso 20457 | Tolerance Table Pdf

Plastics absorb moisture and expand or contract with temperature changes. ISO 20457 evaluates parts under standard climate conditions (typically 23°C and 50% relative humidity) after a specific storage period. How to Use the ISO 20457 Tolerance Table

Specifying tools like a CMM (Coordinate Measuring Machine) or Optical Measurement Systems.

is the definitive international standard governing geometrical and dimensional tolerances for plastic molded parts . Developed to replace older national benchmarks like the German DIN 16742 , this standard provides engineers, mold designers, and quality inspectors with a unified framework to establish realistic manufacturing limits. Unlike metals, plastics undergo complex material shrinkage, environmental expansion, and viscoelastic behavior. Applying standard metal tolerancing to injection-molded polymers inevitably leads to inflated tooling costs and high scrap rates.

The "Tolerance Table" referenced in ISO 20457 is not just a single chart; it is a system based on mathematical formulas that generate tolerance values based on the nominal dimension. iso 20457 tolerance table pdf

If you truly need a working reference without paying for the full standard, these sources offer legally compliant extracts:

To obtain the verified, complete PDF with all technical annexes, material matrices, and advanced geometric tolerance rules, you can purchase it directly from official standard bodies:

Using the official document ensures that the data you are using is up-to-date, as standards are periodically reviewed and updated to reflect new technologies and industry practices. Plastics absorb moisture and expand or contract with

To properly utilize this standard on a technical blueprint or manufacturing contract, follow these steps:

The bridges this gap. It establishes standard tolerance blocks and surface profile criteria within a defined Geometrical Product Specification (GPS) datum framework. It helps stakeholders explicitly delineate between "general tolerances" (applied broadly to non-functional attributes) and "direct tolerances" (assigned to hyper-critical, tight-fit assembly dimensions). TOLERANCES

Below is a representative example of the from ISO 20457 (values in mm, for general-purpose unfilled plastics): tight-fit assembly dimensions).

To standardize expectations between designers and molders, the International Organization for Standardization introduced . This standard replaces the older DIN 16742 standard and provides a robust framework for determining geometric tolerances and deviations.

Ensure your dimensional checks are specified at a defined measurement plane, as draft angles inherently alter the cross-sectional dimensions of a part along its depth.