Meaning
Operational manufacturing thresholds define the maximum allowable percentage of reprocessed scrap material that can be blended with virgin polymer resin during production. Processors set these restrictions to prevent the cumulative thermal degradation that occurs when plastics are repeatedly heated and sheared. Adhering to regrind ratio limits ensures that the mechanical performance and chemical stability of the final product remain within engineering tolerances.
These thresholds govern injection moulding and blow moulding processes but do not apply to thermosetting plastics.
Structural Integrity
Repeated processing degrades the length of polymer chains, which lowers the impact strength and tensile modulus of the molded part. Too much recycled scrap leads to brittle failure and increased defect rates on the factory floor. Chinese export manufacturers track these ratios to ensure products meet global safety standards.
Testing of finished parts confirms that the physical properties remain above minimum tensile limits.
Process Control
Extrusion and injection operations require steady material viscosity to maintain dimensional control. High ratios of reprocessed resin alter the melt flow index, causing dimensional variance or excess flashing in the mold cavities. Production supervisors set feeders to strictly control the volume of reground material added to the hopper.
This precision reduces the rate of scrap generation and lowers production costs.
Compliance Audit
Supply chain inspectors examine factory logs and material consumption records to verify that the blending ratio does not exceed the agreed threshold. Audit protocols require random checks of production runs and raw material stock.
