Lot Tolerance Percent Defective
Meaning ~ Lot tolerance percent defective establishes the maximum percentage of defects allowed in an isolated batch for it to be accepted at a low consumer risk level.
Acceptance Number C
Meaning
Statistical quality control establishes threshold counts of defective units allowed within a sampled lot before rejection occurs. The acceptance number c specifies the maximum count of nonconforming units permitted in a sample for the lot to pass inspection. When nonconformances remain at or below this value, the buyer takes delivery of the entire lot.
If the defect count exceeds this threshold by even one unit, the lot is rejected. The threshold applies strictly to the sample size designated in the sampling plan and stops applying once lot disposition is decided.
Threshold Value
Sampling tables such as ANSI/ASQ Z1.4 fix this numerical limit based on lot size and acceptable quality level. The acceptance number c operates as a rigid boundary during incoming goods inspection.
Contract Trigger
Purchase orders integrate this count to make pass or fail decisions objective. When defect counts match the acceptance number c, acceptance is mandatory under standard contract terms.
Lot Rejection
Confusion occurs when suppliers mistake this limit for an acceptable defect rate in manufacturing. Reaching the threshold in a sample indicates that overall production quality sits near the failure boundary. Exceeding the count forces lot rejection, re-inspection costs, and immediate quarantine procedures.
Contractual disputes arise when inspectors miscount nonconformances or misapply normal inspection tables instead of tightened inspection levels. Maintaining accurate counts protects buyers from substandard component batches.