If you are looking for the official technical specifications or papers regarding this grade, you can find them through these authoritative sources:
These values are indicative of the general tolerance a manufacturer may apply by default when tighter tolerances are not specified. However, to ensure part quality, it is best practice to explicitly call out any dimension that is critical to the part's function, even if the default Tg5 tolerance might suffice. Iso 20457 Tg5
| Tolerance Grade | Primary Application | Relative Precision | Material Examples | Key Design Guidance | | :--- | :--- | :--- | :--- | :--- | | | Packaging parts, high-volume consumer goods | Coarse; lowest cost | PP (polypropylene), LDPE | Tolerances wide enough to absorb high shrinkage with good molding consistency | | TG4 | Precision parts (gears, bearings, complex assemblies) | Fine; premium cost | POM (acetal), PC (polycarbonate), filled nylons | Often reserved for critical CTQ dimensions; requires tight process control and specific material | | Tg5 (Focus) | Housings, general mechanical parts, standard enclosures | Medium; optimized cost-performance | ABS, unfilled PC/ABS, general-purpose thermoplastics | Ideal default for "W" dimensions; use ±0.3 mm (up to 120mm) as typical vision for costing and assembly | | TG6 | Baseline commercial quality for large parts | Medium-coarse; cost optimized for size | ABS, PP, commodity resins | When part envelope exceeds 300 mm and tight flatness is not needed; relax surface profile to avoid core-out penalties | | TG7 | Very large structures, rotational molding | Very coarse; minimum manufacturing cost | PE (polyethylene), soft elastomers | Only use on non-mated surfaces, total envelope > 1m, or when mold is still under development | If you are looking for the official technical
ISO 20457 is a guideline, not a mandate. Many small-to-medium recyclers cannot afford the laboratory equipment (e.g., melt flow indexers, gas chromatography for odour) required for full TG5 compliance. Consequently, much of the global recycling trade still operates on informal specifications. melt flow indexers