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If you are part of a university or professional engineering organization, you may have access via their institutional subscriptions to databases like the CSA Group or iTeh Standards .
ISO 20457 is the international standard governing tolerances and acceptance conditions for plastic molded parts. Within this standard, Tolerance Group 5 (TG5)
When reviewing a design specifying TG5, ensure the following callout is present on the technical drawing to avoid disputes:
ISO 20457 (which superseded the older German standard DIN 16742) is the global benchmark for geometric tolerances in plastic molding. Unlike metals, plastics undergo significant and sometimes unpredictable volumetric shrinkage as they cool from a molten state to a solid.
Processing ConsistencyMinor fluctuations in melt temperature, injection pressure, or cooling time can push a part out of TG5 range. Advanced molding machines with closed-loop controls are typically required. Applications of ISO 20457 TG5
Extreme precision (high cost, specialized tooling). TG4: High-precision components like gears and small wheels.
Achieving TG5 requires total control over three main pillars of production:
To help apply this standard to your specific project, tell me:
Semi-crystalline materials shrink significantly as they cool and crystallize. Achieving TG5 with these materials requires specialized mold compensation and advanced process control.
ISO 20457 helps engineers and toolmakers align on realistic dimensional expectations by accounting for variables such as:
: ISO 20457:2018 officially replaced older German standards like DIN 16742 and DIN 16901 . Key Technical Requirements
If you are part of a university or professional engineering organization, you may have access via their institutional subscriptions to databases like the CSA Group or iTeh Standards .
ISO 20457 is the international standard governing tolerances and acceptance conditions for plastic molded parts. Within this standard, Tolerance Group 5 (TG5)
When reviewing a design specifying TG5, ensure the following callout is present on the technical drawing to avoid disputes:
ISO 20457 (which superseded the older German standard DIN 16742) is the global benchmark for geometric tolerances in plastic molding. Unlike metals, plastics undergo significant and sometimes unpredictable volumetric shrinkage as they cool from a molten state to a solid.
Processing ConsistencyMinor fluctuations in melt temperature, injection pressure, or cooling time can push a part out of TG5 range. Advanced molding machines with closed-loop controls are typically required. Applications of ISO 20457 TG5
Extreme precision (high cost, specialized tooling). TG4: High-precision components like gears and small wheels.
Achieving TG5 requires total control over three main pillars of production:
To help apply this standard to your specific project, tell me:
Semi-crystalline materials shrink significantly as they cool and crystallize. Achieving TG5 with these materials requires specialized mold compensation and advanced process control.
ISO 20457 helps engineers and toolmakers align on realistic dimensional expectations by accounting for variables such as:
: ISO 20457:2018 officially replaced older German standards like DIN 16742 and DIN 16901 . Key Technical Requirements