It establishes realistic dimensional tolerances based on material properties. It defines acceptance conditions for quality control.
Purchase the full ISO 20457:2018 from the International Organization for Standardization .
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.
The tolerances vary depending on the material, as different plastics shrink and mold differently. The standard generally divides materials into groups:
While ISO 20457 is specifically designed for plastic molded parts, ISO 2768 specifies general tolerances for machined metal components. ISO 2768 is typically applied to mold base plates, ejector pins, and other steel components machined via CNC, not to the plastic parts themselves. iso 20457 tolerance table pdf
In the world of mechanical engineering and precision manufacturing, standards are the bedrock of quality. Among the myriad of ISO standards, plays a specific and vital role in ensuring that complex machinery operates smoothly and reliably. For engineers and procurement officers, accessing the ISO 20457 tolerance table PDF is often a critical step in the design and verification process.
Find the row in the table corresponding to your part's length, width, or diameter. For a 45mm long housing, you look at the "30 up to 120" row.
Note: This table represents general dimensional tolerances. For exact allocations based on specific compound shrinkage rates and tool-bound vs. non-tool-bound dimensions, please reference the official ISO 20457 PDF framework. 5. Tool-Bound vs. Non-Tool-Bound Dimensions
Wall thickness, ribs, and overall geometry influence cooling rates and subsequent shrinkage. The tolerance tables within ISO 20457 offer engineers
A true “tolerance table” in ISO 20457 depends on:
Yes — but not a fixed one.
Do not default your engineering drawings to TG2 or TG3 unless absolutely necessary. Tightening tolerances exponentially increases mold manufacturing costs and cycle times.
standard (which replaced the older DIN 16901) provides a comprehensive system for determining manufacturing tolerances for plastic molded parts. It classifies tolerances into Tolerance Groups (TG) The standard generally divides materials into groups: While
ISO 20457 is an international standard that specifies tolerances for linear and angular dimensions, as well as geometric tolerances, for features on parts and products. The standard provides a comprehensive tolerance table that engineers and manufacturers can use to ensure precision and accuracy in their designs and manufacturing processes.
The standard defines nine , ranging from TG1 (the most precise/tightest) to TG9 (the coarsest/widest).
ISO 20457 (full title: “Plastics moulded parts — Tolerances and acceptance conditions”) specifies possible manufacturing tolerances for plastic molded parts. First published in 2018, this standard replaced national standards such as Germany’s DIN 16742, bringing a unified global framework for plastic part tolerancing. The standard applies to all integral features with general tolerances, using a surface profile tolerance within a specified datum system, and allows for additional specifications when functional needs require tighter control.
To properly utilize this standard on a technical blueprint or manufacturing contract, follow these steps: