Map your resin profile to the ISO 20457 material data sheets to determine its baseline achievable Tolerance Grade before finalizing your 2D engineering drawings.
It covers geometric dimensioning and tolerancing (GD&T) specific to plastics, including straightness, flatness, and roundness.
The standard category for standard consumer goods, electronic enclosures, and structural parts utilizing common thermoplastics like ABS or Polypropylene. iso 20457 tolerance table pdf
When designing or manufacturing plastic injection-molded parts, achieving perfect dimensional accuracy is a significant challenge. Unlike metals, plastics exhibit high shrinkage, thermal expansion, and viscoelastic behavior.
The heart of ISO 20457 is its system of nine tolerance grades, designated to TG9 . TG1 represents the highest precision, while TG9 is the coarsest. This is a significant change from its predecessor, DIN 16901, which only had six groups. Map your resin profile to the ISO 20457
Let’s break down what ISO 20457 really is, and where to get the correct tolerance information for your drawings.
| Nominal size (mm) | PT3 (Fine) | PT5 (Medium) | PT7 (Coarse) | |------------------|------------|--------------|---------------| | up to 10 | ±0.10 | ±0.25 | ±0.50 | | 10 – 25 | ±0.15 | ±0.35 | ±0.70 | | 25 – 63 | ±0.20 | ±0.45 | ±0.90 | | 63 – 100 | ±0.30 | ±0.60 | ±1.20 | | 100 – 160 | ±0.40 | ±0.80 | ±1.60 | TG1 represents the highest precision, while TG9 is
If you are designing high-volume medical or automotive parts, the full PDF is a necessary investment. For prototyping or low-volume industrial design, a high-quality summary table combined with good communication with your moulder may suffice.
Do not apply metal standards (e.g., ISO 2768-m) to plastics. Define high-precision tolerances directly on dimensions.
This article breaks down how to read an ISO 20457 tolerance table, the factors influencing these tolerances, and how to apply them to your PDF technical drawings. What is ISO 20457?