Statistical Acceptance Sampling Protocols for Paperboard Package Lot Verification
Statistical lot verification protects packaging buyers by tying standardized sample testing directly to batch acceptance quality limits and contract settlement terms.
Tightened Inspection
Sampling Rigour
Increased sampling frequency provides a higher level of scrutiny to improve the probability of finding defects in a production batch. Implementing tightened inspection occurs when a supplier has failed to meet the specified quality levels in recent shipments. This mode of operation uses smaller acceptance numbers and larger sample sizes compared to normal inspection.
It protects the buyer during periods of inconsistent production.
Regulatory Protocol
Switching between different levels of scrutiny is defined by standards such as ISO 2859-1. A move to tightened inspection is mandatory when two out of five consecutive lots are rejected. This shift forces the manufacturer to improve their process controls to avoid further rejections.
Only after five consecutive lots are accepted under these harder conditions can the system return to a normal sampling plan. Documentation of these changes must be kept for audit purposes to prove that the quality management system is functioning as intended.
Pass Threshold
Acceptance of a batch becomes more difficult to reach when these rules are in effect. Under tightened inspection, the allowable number of defects for a given lot size is reduced. This means a batch that might have passed under a normal plan will now be rejected.
The goal is to provide a strong incentive for the producer to maintain high standards.