Unlike metals, plastics undergo significant dimensional changes during and after production due to factors like thermal contraction, material shrinkage, and environmental moisture. ISO 20457 provides a standardized framework to calculate acceptable dimensional deviations for injection molded, compression molded, and blow molded plastic parts. Why Engineers Search for the ISO 20457 PDF
So any PDF that claims to be a universal “ISO 20457 tolerance table” is likely a simplified summary from a textbook or company standard.
Ranges (e.g., 0-30 mm, 30-100 mm) determine the base allowance.
While the full PDF document contains extensive calculation formulas for custom variations, standard applications rely on generalized reference tables. Below is a simplified representation of typical standard tolerance values (TG5 and TG6) for nominal dimensions. Nominal Dimension Range (mm) TG5 / Standard Precision ( ±plus or minus TG6 / Commercial Grade ( ±plus or minus 1 to 3 3 to 6 6 to 10 10 to 18 18 to 30 30 to 50 50 to 80 80 to 120 120 to 180 180 to 250 iso 20457 tolerance table pdf
*This paper is a technical summary for educational purposes. For manufacturing, quality control, or legal compliance, you must purchase and reference the official, current version of the ISO 20457 standard document directly from
Fluctuations in injection pressure, melt temperature, and cooling cycles. 3. ISO 20457 Tolerance Groups (TG) Explained
and precision classes to define allowable deviations. A critical requirement is that a callout must include the grade and environmental conditioning (e.g., ISO 20457–TG6 + 23°C/50%RH ) to be enforceable. Super-Ingenuity Tolerance Categories (Materials) Ranges (e
A universal language between designers and molders worldwide.
Understanding ISO 20457: The Ultimate Guide to Plastic Molded Part Tolerances
Note: The format +X / 0 indicates that the pipe can be larger than nominal by X mm, but cannot be smaller than the nominal size (ensuring it can seal). Nominal Dimension Range (mm) TG5 / Standard Precision
which includes the first few pages and Table 8 (General Tolerances). Detailed Overviews
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
A detailed explanation of how to apply ISO 20457 and DIN 16742, including shrinkage equations, can be found on Tolerance Overview (TG6):