Engineering Changes for Custom Metal Assemblies: Control the Cutover

Define the change in functional terms

State what changes, why it changes and which parts or assemblies are affected. Identify the drawing, model and bill-of-material revisions together. A revised hole or finish can affect a mating component even when that component’s geometry remains unchanged. Review the assembly relationship before sending a new file, and distinguish the proposed design from the approved release.

Assess existing material and work

Count finished stock, work in progress, purchased components and material already committed to the old revision. Decide whether each can be used, reworked, segregated or rejected under an authorized disposition. Do not leave the supplier to infer this from a revised drawing date. The disposition should include quantities and identity so the cutover can be verified against actual inventory.

Set an unambiguous effectivity rule

Define when the change takes effect using the appropriate purchase order, lot, serial number or other controlled reference. A calendar date alone may be unclear when several lots move through production at different stages. Record whether mixed revisions are permitted within an assembly or shipment. If interchangeability is limited, identify the allowed combinations in the relevant assembly and inspection documents.

Update the manufacturing evidence

Review programs, fixtures, gauges, work instructions and inspection reports affected by the change. Determine whether a new first article or focused requalification is needed. A changed drawing can require process changes even when the external appearance remains similar. Keep the old approved records available for traceability while preventing them from being mistaken for the active production instruction.

Verify the first shipment after cutover

Identify the first lot produced under the new revision and check its documentation, labeling and functional evidence. Reconcile the remaining old-revision stock against its authorized disposition. Close the change only after the relevant supplier and internal records agree. If an issue appears later, the organization should be able to identify which units received each revision without reconstructing the decision from email attachments.

Approval checklist and evidence

Worked review example

Illustrative scenario: a bracket hole moves in revision C, while mating adapters already exist under revision B. The change notice specifies the new drawing but says nothing about the assembled stock. The revised plan defines which combinations are acceptable, segregates incompatible inventory and identifies the first new-revision lot. Inspection then checks the assembly relationship and the actual cutover, rather than confirming only that the newest file was received.

Information for the engineering review

• Affected drawings, models and assembly list
• Inventory and work-in-progress disposition
• Order, lot or serial effectivity
• Updated process and inspection evidence
• First-shipment and remaining-stock reconciliation

Discuss this requirement with KEC Tour using the controlled drawing, the relevant mating interfaces and the review information above. Identify the decision that needs confirmation and the acceptance evidence expected with the first parts.

Sources and further reading

• ISO quality management
• ASME drawing and tolerancing standards

Frequently asked questions