The tolerance tables within ISO 20457 offer engineers a reliable reference for specifying achievable tolerances based on nominal dimension ranges, tolerance grades, and dimension types. When applied correctly—with clear specification of TG grades, acceptance conditions, and W/NW classifications—ISO 20457 reduces costly disputes between designers, mold makers, and quality inspectors.
): Amorphous plastics (like Polycarbonate or ABS) experience low, uniform shrinkage (approx. 0.3% to 0.7%). Semi-crystalline plastics (like Polypropylene or Polyethylene) experience high, anisotropic shrinkage (approx. 1.5% to 3.0%), making them much harder to hold to tight TGs. iso 20457 tolerance table pdf
Do not default to PT1. Interview your injection moulder first. Ask: The tolerance tables within ISO 20457 offer engineers
Understanding where ISO 20457 fits in the standards landscape helps justify its use to colleagues. Do not default to PT1
Download ISO 20457 Tolerance Table PDF for Precision Engineering
Do not apply metal standards (e.g., ISO 2768-m) to plastics. Define high-precision tolerances directly on dimensions.