Containment Hold and Sort¶
Defect containment response — instantiates Inline vs. Offline Inspection Trade-Off
Quarantines suspect lots and performs sorting or reinspection after a defect signal appears, so bad units are contained before they escape downstream.
Containment Hold and Sort is not an inspection placement at all — it is the response that fires after an inspection somewhere else has raised a flag. Its defining move is to draw a boundary around a suspect population the instant a signal appears — a failed check, a customer complaint, an out-of-spec measurement — and hold everything inside that boundary until each unit has been proven good or bad. Where the other mechanisms decide where and how much to inspect, this one decides what to do with product already made once doubt exists: freeze it, then sort or reinspect it 100% to separate the good from the bad. It is the machinery that keeps a single detected defect from becoming a batch of escapes, and its whole design turns on drawing the containment window neither too narrow (escapes leak past the edges) nor too wide (good product is needlessly held and re-handled).
Example¶
On a brake-caliper assembly line, an inline torque check flags one fastener that seated 20% below spec. The immediate question is not "fix the tool" — it is "how many other calipers built since the tool was last known good are also suspect?" Containment Hold and Sort answers it. The team times the containment window back to the last verified-good check — the whole run since the previous shift's first-piece verification, about 900 calipers already palletized and two more on a truck to the paint shop — and slaps a red HOLD tag on all of it. Because a loose brake fastener is a safety-critical escape, the disposition is not "sample and hope" but a 100% re-torque sort: every held caliper is re-checked, ~30 out-of-spec units are pulled and reworked, the rest released. The two on the truck are recalled before they are painted over. The line keeps running; the suspect population is what gets frozen.
How it works¶
- Bound the suspect population. Trace the signal back to the last point the process was known good and forward to wherever the product has flowed; everything between is quarantined. Traceability (lot codes, timestamps, serial ranges) sets how tight this boundary can be.
- Grade by criticality. How the held stock is dispositioned depends on the defect class: a safety- or regulatory-critical escape forces 100% sort or scrap; a cosmetic one may allow sample-and-release.
- Sort, don't just inspect. Each held unit is separated into good / rework / scrap, and the good stream is released. The point is disposition of physical inventory, not a statistical verdict.
- Hand off root cause. Containment stops the bleeding; it explicitly does not fix the process — that goes to a separate corrective loop.
Tuning parameters¶
- Containment window width — how far back and forward the quarantine reaches. Wider is safer but freezes and re-handles more good product; narrower risks leaving escapes outside the net.
- Disposition rule by defect class — the map from criticality to action (scrap / 100% sort / sample-and-release). Sets how conservative containment is per defect type.
- Trigger sensitivity — what counts as a signal worth containing on. A hair-trigger contains constantly and disrupts flow; a dull one lets suspect stock ship before the hold lands.
- Release evidence bar — how much re-checking is required before held stock is freed. Higher bars cut escape risk but extend the hold and tie up inventory.
When it helps, and when it misleads¶
Its strength is damage control under uncertainty: when you know something is wrong but not which units, it converts an ambiguous signal into a bounded, dispositioned population and keeps a defect from propagating downstream. It is the D3 step of a structured containment discipline[n1] — the fast interim action that protects the customer while the real fix is still being found.
Its failure mode is that containment gets mistaken for correction. A team that sorts the same defect out week after week feels productive while the process that makes the defect never changes — "inspecting quality in" instead of building it. Two classic misuses: setting the window too narrow so escapes slip past the quarantine edge, and treating a completed sort as case-closed without ever driving root cause. The guarding discipline is to time-box every hold to a corrective action and to treat a repeat containment on the same mode as an escalation trigger, not a routine.
How it implements the components¶
containment_and_rework_trigger— this is its core: the halt / quarantine / sort / rework response that fires on a defect signal.defect_criticality_and_escape_cost_profile— it reads the defect's severity and escape cost to decide whether the held stock is scrapped, 100%-sorted, or sampled and released.
It does not decide where routine inspection sits or how much of it to run (inspection_placement_map, coverage_strategy_choice), and it does not change future inspection intensity in response to the event (inspection_policy_revision_loop — that's control_chart_triggered_inspection_escalation, the sibling it is most easily confused with: escalation adjusts the go-forward inspection policy, whereas Containment Hold and Sort only dispositions the product already made).
Related¶
- Instantiates: Inline vs. Offline Inspection Trade-Off — it supplies the "what happens after a detection" half of the policy.
- Consumes: a detection signal from an inspection mechanism such as automated_inline_sensor_check or end_of_line_batch_release_test.
- Sibling mechanisms: control_chart_triggered_inspection_escalation · first_article_or_setup_inspection · statistical_acceptance_sampling_plan
Editorial Notes¶
Form Classification¶
Form family: Intervention, Treatment & Transformation
Rationale: After a defect signal, the mechanism quarantines the suspect physical population and sorts every held unit into good, rework, or scrap, directly changing inventory state and stopping escapes.
Nearest alternative: Control, Automation & Runtime — A signal triggers the response, but quarantine and disposition are bounded physical containment actions rather than a continuing automatic sense-act loop.
Review outcome: Adjudicated after independent review; high confidence.
Origin Attribution¶
Primary origin: Engineering & Design
Origin pattern: Single lineage
Present-day reach: Specialized
Rationale: Manufacturing quality practice cohered lot containment, quarantine, and 100-percent sort or reinspection after a defect signal.
Related originating lineages:
- Operations Research — Quality-control sampling and traceability help bound the suspect production window efficiently.
Review resolution: Manufacturing quality engineering clearly cohered lot quarantine and complete sorting; operations research contributes capacity and prioritization methods.
Review outcome: Reconciled after independent review; high confidence.
Notes¶
[n1] The Eight Disciplines (8D) problem-solving process treats interim containment (its D3 step) as distinct from permanent corrective action (D5–D6). The separation is deliberate: containment protects the customer immediately, but a team that stops at containment has controlled the symptom without curing the cause. ↩