: Coarse to very coarse (e.g., packaging or parts with high, unpredictable shrinkage). Key Components of an ISO 20457 Callout
The standard categorizes production accuracy into nine Tolerance Groups (TG1 to TG9): Iso 20457 Tg5
: The environmental state (typically 23°C and 50% relative humidity) at which the part must be measured. Datum Scheme : The reference points used for measurement. : Coarse to very coarse (e
: Extreme precision (expensive and difficult to maintain). TG4 : High precision (e.g., gears or precision wheels). : Extreme precision (expensive and difficult to maintain)
For more detailed engineering data, you can view the official abstract on the ISO website or check the DIN ISO 20457 comprehensive guide .
: Whether using a CMM (Coordinate Measuring Machine) or a manual fixture. Why Choose TG5?
ISO 20457 , which replaced older standards like DIN 16901 and DIN 16742, defines the geometrical and dimensional tolerances for plastic molded parts. Unlike metal machining, plastic molding must account for unique variables such as material shrinkage, thermal expansion, and moisture absorption. Understanding the TG5 Classification