Production part approval: the gate between samples and series supply

Parts made the way they will be made

The central requirement is that the submitted parts come from production tooling, the production process, the production material source and, as far as possible, the intended rate and the operators who will run it. Approving parts produced under laboratory conditions by a process engineer approves nothing useful, because none of the variation that matters was present. Where a supplier requests approval on parts from a temporary tool or a trial process, that is an interim decision with a defined expiry and a plan to close it, and it should be recorded as such rather than allowed to become permanent by neglect.

What the submission package should contain

Scope it to the risk. A minimum sensible package identifies the part and revision approved, the process route and machine, dimensional results against the drawing for the sample quantity, material and performance evidence where called for, capability data on the designated critical characteristics, the control plan the supplier will operate, the packaging as it will be shipped, and a signed declaration by someone at the supplier with authority. Large industries have elaborate formats for this; a smaller operation can achieve the same effect with a page and honest evidence, provided the scope of the approval is unambiguous.

The approval is tied to a configuration, not to a supplier

What gets approved is a part, at a revision, made at a named site, on identified tooling, by a stated process, from a specified material source. Change any of those and the approval no longer covers what is being shipped. Suppliers frequently do not realise this, so state the boundary in writing and set out which changes require resubmission before implementation. The moves that most often slip through unnoticed are a move to a second machine, a change of sub-supplier for a material or a coating, and a relocation of the line within the same plant.

Deciding when the evidence is not perfect

Real submissions arrive with something outstanding: a dimension marginally outside on one sample, a capability figure below expectation, a test result still pending. The options are approval, conditional approval with defined actions and an expiry, or rejection. Conditional approval is the useful middle ground and the most abused, because conditions get set and never followed up. If you grant it, name the actions, the owner and the date, and diarise the review. Approvals granted under launch pressure with open conditions are the origin of a large share of later supplier quality problems.

Keeping the record where the next person will find it

Approval records are consulted years later, usually during a problem, often by someone who was not involved. Store the package where the current part record points to it, keep the signed decision with its scope and any conditions, and retain the approved samples where physical reference matters. Plants that keep this material in a personal folder or an email thread discover the gap during a customer escalation or an audit, at the exact moment a clear record of what was approved and when would have ended the discussion. Agree retention periods with the supplier as well, since their copy of the evidence is often the more complete one.

Frequently asked questions

When does a part need to be resubmitted for approval?

Whenever something in the approved configuration changes: the tooling, the machine, the process route, the material or its source, a sub-supplier of a coating or treatment, the manufacturing location, or the drawing revision. A long production interruption also justifies resubmission, because setters, settings and tooling condition all drift while a job is dormant. The rule should be written into the supply agreement, since suppliers otherwise apply their own judgement about what counts as significant, and their judgement is not yours.

How many parts should a supplier submit for approval?

Enough to show the process rather than a single good part, drawn from a continuous production run rather than selected. The quantity depends on the process and the consequence of failure: a moulded part with several cavities needs parts from every cavity, a machined part needs samples spanning a run so tool wear is visible. Sampling that lets a supplier submit its best pieces defeats the purpose, so specify how the samples are to be taken as well as how many.

Who inside the buying company should sign the approval?

Someone with the authority to stop the launch, which in practice means quality rather than purchasing, with engineering confirming that any deviation is acceptable in the design. Splitting the decision so purchasing can approve on commercial grounds undermines the gate entirely, because launch pressure always favours shipping. Record the names, because approvals signed by an unidentified party are worth little during a later investigation and provide no accountability for the conditions attached.