Meaning
Geometric tolerance classifications define permissible deviations for high-precision injection moulded plastic components. Technical drawings specify tolerance class TG6 when parts require tight mechanical fits and high interchangeability in complex assemblies. Achieving this precision level demands engineering thermoplastics with low amorphous shrinkage, such as polycarbonate or modified polyphenylene ether blends.
Standard commodity resins with high crystalline shrinkage cannot reliably hold TG6 limits across extended production runs.
Dimensional Standard
Normative reference tables establish allowable linear and angular variations based on nominal part dimensions. Standard DIN 16742 guidelines assign tolerance class TG6 to precision applications where tool wear and process drift must be strictly controlled. Compliance requires part verification in temperature-controlled metrology environments following standardized conditioning periods.
Tooling Requirement
Toolmakers construct high-precision moulds using hardened tool steels and tight-tolerance core slide guidance systems to support manufacturing within tolerance class TG6. Tool cavities must be oversized precisely using verified material shrinkage factors to ensure final part dimensions land within target bands. Tool temperature control units must maintain steel temperatures within tight boundaries to prevent thermal variance across cavities.
Moulding Limit
Unstable barrel temperatures or high regrind content cause dimensional variations that exceed tight manufacturing windows. Process control must remain stable to consistently produce parts within tolerance class TG6.
