Thermoforming against Injection for Volumes below Fifty Thousand Units
Thermoforming delivers lower total landed cost below fifteen thousand units by saving upfront tooling capital, beyond which injection piece price efficiency dominates.
TG5 Tolerance
Meaning
Dimensional variation limits define the acceptable range for the geometric profile of high-precision thermoplastic components during injection moulding. The tg5 tolerance serves to constrain the permissible deviation from the master cavity dimensions to ensure mechanical fitment in complex assemblies. Engineering specifications mandate these values to compensate for material shrinkage and thermal expansion that occur as parts transition from molten resin to solid forms.
Manufacturing Constraint
Mould makers assign specific adjustments to steel dimensions based on the expected shrinkage rates of the selected polymer grade. If the tg5 tolerance sits too tight for the chosen resin, the resulting parts fail to clear the mould or suffer from stress cracking during ejection. Process engineers monitor the cavity pressure and cooling time to hold the part within this predefined window.
Quality Verification
Metrology departments conduct standardized batch inspections to verify that dimensions remain within the allowable band. Testing protocols typically involve measuring sample lots against the nominal cad model under controlled ambient temperatures. Consistent results demonstrate the capability of the moulding process to produce parts that satisfy the design requirements without excessive scrap.
Economic Impact
Material choices dictate the cost-effectiveness of maintaining such narrow bounds during high-volume production. Virgin resins provide the stability necessary to stay inside the tg5 tolerance without frequent recalibration of the injection machine. Regrind use often introduces viscosity shifts that push the dimensions outside the allowable range and force expensive secondary machining operations.