Unlike scattered company-specific tolerance notes, the ISO 20457 PDF delivers a set of limit deviations applicable when no individual tolerance is explicitly shown on a drawing.
If you have been searching for the you are likely looking for a clear, actionable reference for geometrical tolerancing of moulded plastics, castings, and general dimensional variations. This article provides a deep dive into what ISO 20457 is, where to find the official tolerance tables, and how to apply them correctly in your design workflow.
ISO 20457 is not part of the ISO 2768 series (General Tolerances for machined parts). Instead, it focuses on manufacturing processes that inherently have higher variability:
When users search for an , they are specifically looking for the numerical limits that govern the geometry of fittings. The standard breaks these tolerances down into several critical categories. iso 20457 tolerance table pdf
(Where "m" indicates the Medium tolerance class for linear dimensions, angular dimensions, and form simultaneously.)
Note: For precise applications, you should refer to the full International Standard ISO 20457 to identify the specific TG appropriate for your resin type and shrinkage rate. Recommended Resources
: Reserved for extreme precision parts requiring specialized tooling and tight process control. ISO 20457 is not part of the ISO
: A "good feature" of this standard is its requirement for a specific reference atmosphere—typically 23 °C and 50% relative humidity —to ensure measurements are repeatable and enforceable.
Hyperlinks (in digital PDF) to:
: Unlike metal standards, it accounts for the unique behavior of plastics, such as processing shrinkage and thermal expansion. (Where "m" indicates the Medium tolerance class for
For plastic parts, even "Fine" class allows wider variation than machined metal parts. Do not use ISO 20457 for precision assemblies like bearings.
callout, Sarah’s casings finally fit perfectly. She didn't just have a PDF; she had a common language that linked her design, Jim’s tools, and the quality lab's sensors. ISO 20457 Tolerance Table Overview | PDF - Scribd