8D containment action checklist (D3)

Why containment fails

Many weak D3s are not lazy, they are incomplete: the stock in transit was forgotten, the sort used the same check that let the defect escape, or nobody wrote down when sorting may end. Containment protects the customer while you find the root cause; it is not the fix. For the difference, see containment vs corrective action.

Step 1: stop and find every suspect location (hours 0 to 4)

• Define the suspect range: lots, dates, shifts, machine or cavity, from the last known good part to now.
• Stop shipping unsorted parts from the suspect range.
• List every location: customer incoming stock, line side and WIP, service or spare-parts stock, trucks and cross-docks, external warehouses, supplier finished goods, WIP, rework and quarantine areas.
• Count each location. A quantity per location, adding up to the suspect total, is the first thing a customer SQE checks.
• Ask the customer whether parts are already assembled into higher-level products; that is a separate decision for them.

Step 2: set sort and rework criteria (hours 2 to 8)

• Write the reject criterion as a measurable characteristic with a limit, not “check for defects”.
• Pick a sort method that can detect the failure mode. If the original check missed it, a repeat of that check is not containment.
• Show the method works: seeded parts with the defect, run blind through each sorter. This shows the method can find the defect; it does not prove it finds every one.
• Check the gauge is adequate for the limit (see Gage R&R basics).
• Without a written instruction, a re-check and, where required, the customer's agreement, do not rework: scrap or keep on hold.
• Put it in one sorting instruction: use the containment sorting instruction template.

Step 3: sort, record and mark (day 1 onwards)

• Record per location and per lot: quantity sorted, quantity rejected, sorter, date.
• Keep the rejects; they are evidence for D4.
• Mark sorted parts and their packaging so they can be told apart from unsorted stock, for example “Sorted 100 percent for burr on edge A, 26 Oct, team B, lots 2641 to 2648”. Avoid wording that promises more than the sort checked.
• Use the customer's own term and label colour if they prescribe one.
• Define the clean point: the first lot or date known to be free of the defect (sorted, or made after the fix), and how the customer can recognise it on the label.

Step 4: decide in advance when containment ends

• Containment stays until the permanent action is implemented and an exit criterion is met.
• Set the criterion now, with numbers: for example zero defects in at least 3 divided by the rate you want to show. For example, 3 / 250 ppm = 12,000 parts supports a rate below about 250 ppm at the 95 percent level (rule of three, see the CAPA effectiveness check).
• Record the date containment was lifted and why.
• Sorting with a sample plan instead of 100 percent is a separate decision; see the AQL sampling plan example for what a sample can and cannot show.

Worked example (fictional)

A customer finds 3 brackets with a burr on edge A. The suspect range is lots 2641 to 2648. Counted stock per location:

• Sort method: tactile check with a gauge pin on edge A. Before the sort, 10 seeded burr parts went blind through each of 3 sorters (30 checks): all found. 30 of 30 found supports a detection rate above about 90 percent at the 95 percent level, not 100 percent.
• Result: 14 rejects in 8,000 sorted, about 1,750 ppm in the suspect range; 7,986 parts marked as sorted and released.
• The 14 rejects went to D4. Note that 1,750 ppm is the rate in the suspect range, not the process rate.
• Exit criterion written on day 1: after the permanent action, zero rejects in at least 12,000 parts, which supports a rate below about 250 ppm (3 / 12,000) at the 95 percent level. Customer agreement recorded.

Quick D3 self-check before you send

• Every location listed and counted, and the counts add up.
• Reject criterion is measurable; sort method can detect the failure mode.
• Sorted stock marked with what was checked, by whom, and when.
• Clean point defined and visible to the customer.
• Owner and date for each action; exit criterion with numbers.

For what the report itself must show, see the D3 containment evidence checklist; for examples by sector, containment actions examples. Set the dates with the 8D deadline calculator and write it up in the 8D report template.

FAQ

How fast should containment start?

Many customers expect containment to start within 24 hours of the complaint, and some set a shorter time. Check your customer's supplier manual; the deadline calculator helps you set the D3, D5 and D8 dates.

What is the difference between this checklist and the D3 evidence checklist?

This page is the action list: what to do, in what order, in the first hours and days. The D3 evidence checklist covers what to show in the 8D report afterwards: quantities, sort method, clean point, records, owners and exit criteria.

What should the label on sorted parts say?

State what was done, not a promise: the characteristic checked, the method, the date, the sorter or team, and the lot or date range. Some customers prescribe their own term and label colour; use theirs. A label that only says 'OK' tells the customer nothing they can check.

When can containment stop?

When the permanent action is in place and an exit criterion set in advance is met, for example zero defects in a defined volume after the fix. Agree the criterion with the customer where their manual requires it. Common practice, not a rule.

Related

• Supplier complaint letter template
• CAPA effectiveness check
• All free quality tools