Supplier Lot Rejection Rate

A manufacturer receives multiple supplier lots of raw material or components, and some lots fail inspection and are rejected, so the rejection rate tracks how often that happens under a consistent lot definition and acceptance rule. Define a lot, which may be a supplier batch, delivery lot or buyer-defined inspection unit, and do not equate orders and lots, since one purchase order can include several lots.

Define rejection as an authorised final disposition after inspection, not the first failed sample alone, because a lot held for more testing is not yet rejected. Choose the denominator by counting inspected lots with final accept or reject decisions during the period, since received lots awaiting inspection belong in an open queue, not necessarily the decided-rate denominator.

An illustrative rate is eight rejected lots out of 200 lots with decisions, or 4%, and the business should state whether partial rejection counts as a rejected lot or whether units are measured separately. Oracle describes supplier-quality checks during receiving with inspection results recorded after physical receipt, so the receipt and inspection are different events.

Understand sampling, because a sampling plan can accept or reject a lot based on tested units; ASQ describes acceptance-sampling standards, and the actual plan should fit product risk and buyer requirements. Do not assume an accepted sampled lot has zero defective units, since sampling reduces uncertainty under a defined rule and is not inspection of every piece.

Record the reason, because wrong specification, contamination, damage, missing certificate and labelling error need distinct follow-up, and a rejected label without evidence is not a useful supplier conversation. Link traceability by storing supplier, product, lot ID, receipt, inspection report and disposition, which supports later recalls or corrective actions.

Separate supplier cause from transit damage, since a delivery can be damaged after leaving the supplier and responsibility should be investigated before the event enters a supplier performance score. Review severity as well, because a rejected safety-critical lot may matter more than several minor packaging failures, so show severity alongside rate.

Compare similar items, since a supplier providing complex custom parts may have a different inspection mix from a commodity supplier and direct rate comparison can be unfair without context. Watch inspection intensity, because if the buyer tests more characteristics this month a rate increase might reflect better detection, so note changes in sampling and specification.

Check incoming volume as well: two rejections among ten lots make a volatile 20% rate, while 20 among 1,000 (2%) is more stable, so report counts and the denominator. Handle rework and sorting by recording the original disposition and the final accepted quantity rather than silently replacing the history when a supplier sorts a lot so some units become acceptable.

Avoid release before disposition, because stock under quarantine should not become pickable while the rejection decision or concession is pending, and set a response route in which the supplier is informed of observed defects with evidence and asked to correct them under the contract. Track repeat causes, separate lot and unit rates (a 4% lot rejection rate does not say what share of pieces was lost, and a single huge lot can dominate the unit impact), check financial effects such as replacement lead time, production stoppage, freight and scrap without assuming the supplier owes every cost, and keep an accepted concession visible as different from meeting the original specification; a low final rejection rate can also coexist with a growing undecided queue, so show queue age and releases separately, because for owners the rate is an early supplier-quality signal only while definitions and evidence stay consistent.