Din 16742 - Tg5 May 2026

For a 50 mm flat surface in TG5, permissible flatness deviation is roughly 0.08 mm. Compare to TG8 (0.02 mm) which requires mirror-finish tool surfaces.

Thin walls are the nemesis of plastic molding. For a 2 mm nominal wall thickness, TG5 allows a deviation of ±0.07 mm. This is critical for fluid flow channels or electrical insulation barriers.

Even experienced designers misuse TG5. Avoid these errors: din 16742 - tg5

DIN 16742 is the German standard for Tolerances for injection-molded plastic parts. It replaced older standards like DIN 16901. It provides a systematic way to define allowable deviations in dimensions, geometry, and surface for thermoplastics, thermosets, and elastomers.

The standard defines several tolerance groups (TG) – from TG1 (very fine/precision) to TG7 (very coarse). For a 50 mm flat surface in TG5,

TG5 sits in the middle, representing normal industrial precision for injection molding without special tooling or process controls. It is the most commonly specified tolerance grade for functional plastic parts.

| TG level | Typical use | Relative cost | Mold precision needed | |----------|-------------|---------------|------------------------| | TG1–TG2 | Medical, optical, micro parts | Very high | Precision tooling, hard steel | | TG3–TG4 | Precision fits, moving parts | High | Good toolmaking | | TG5 | General mechanical parts | Standard | Standard CNC mold | | TG6–TG7 | Non-critical covers, spacers | Low | Less precise mold | | TG level | Typical use | Relative

The selection of TG5 is typically driven by the material choice and the part geometry.