Meaning
Threshold specifications define the limits of acceptable variance for raw material or finished part properties during production. Established batch rejection criteria allow a quality manager to quarantine resins that fall outside a datasheet tolerance for viscosity or moisture content. These parameters ensure that only materials meeting the validated process window enter the injection moulding machine.
Quality Standard
Predefined measurements determine the suitability of a polymer lot for high precision manufacturing. A specific batch rejection criteria set for a medical grade polymer might focus on trace metal counts and molecular weight distribution. This rigorous screening prevents downstream failures where part dimensions drift due to inconsistent shrink rates.
Operational Boundary
Production efficiency relies on the consistent application of pass or fail logic to incoming feedstock. When a supplier delivers a resin lot with a melt flow index exceeding the agreed range, the batch rejection criteria provide the basis for a formal claim. This systematic approach reduces the risk of nozzle freeze or flashing during the moulding cycle.
Decision Point
Formal documentation outlines the steps taken when a material fails to meet the internal requirements. The batch rejection criteria include a secondary verification step to confirm the initial test result was not an error in sampling or preparation. Once confirmed, the lot is returned to the supplier or repurposed for non-critical applications where physical properties are less demanding.
This process includes an assessment of the economic impact of the loss and the timeline for a replacement shipment to arrive. By maintaining a strict log of these decisions, a moulder can identify patterns in supplier performance over several years.
