Material Defects Recorded as Process Defects
When a defect turns up on the line, it usually gets logged as a process defect first. Trace it back, though, and the root cause is often incoming material: a molded part out of tolerance, or a bracket with plating that's too thin. The trouble is that nobody can put a number on how often this happens. If defect records don't capture the lot number that was consumed, there's no way to tell material problems from process problems, and the blame ends up on the operators.
Incoming inspection tends to become a rubber stamp for three reasons:
Designing Inspection Criteria
Sampling Plans by Part and Supplier
KS Q ISO 2859-1 (sampling by attributes) uses lot size and inspection level to pick a sample size code letter, then uses the AQL (acceptance quality limit) to set the accept/reject numbers. Take a lot of 1,200 units at general inspection level II: that gives code letter J and a sample of 80. Under normal inspection at AQL 1.0, up to 2 defectives is an accept and 3 or more is a reject. Criteria should follow how critical the part is, with tighter AQLs for safety parts and looser ones for cosmetic parts.
Switching Inspection Levels Based on Performance
ISO 2859-1 includes switching rules. Under normal inspection, if 2 out of 5 consecutive lots are rejected, you move to tightened inspection. Once 5 consecutive lots are accepted under tightened inspection, you return to normal. Consistently good results let you move to reduced inspection with smaller samples. Skip-lot inspection, where some lots aren't inspected at all, is covered by a separate standard (ISO 2859-3) and is meant only for suppliers with a long, stable record. Nobody should have to track these switches from memory. The system should read the lot history and recommend them.
Checking Supplier CoAs Against Your Own Results
Filing a supplier's certificate of analysis tells you nothing by itself. Store its values next to your own measurements of the same characteristics, and flag any deviation beyond tolerance. That's how you find out whether a supplier's certificates can be trusted.
Connecting Inspection Results to Inventory and Production
Supplier Quality Evaluation and Corrective Action
Calculate these metrics automatically for each supplier every month:
When a supplier goes over threshold, issue a SCAR (Supplier Corrective Action Request) and track it through root cause analysis, the supplier's response, and effectiveness verification. Judge effectiveness on actual results from lots received after the fix. That's what filters out paper-only responses. Tie quarterly ratings to inspection levels and order share so that suppliers with good quality get a real benefit.
Rollout Stages and the POLYGLOTSOFT Approach
Splitting the rollout into three stages is more reliable than building everything at once:
POLYGLOTSOFT builds incoming inspection and SQM systems on top of your existing ERP receiving data and MES consumption history. If you want to close the gaps in your quality data without replacing the systems you already run, request a consultation through our contact page.