T1 Sampling Explained: What Happens Between Mould Completion and Production

Updated: 2026-10-22

Sampling connects a completed mould to an agreed production release. T1 usually names the first documented trial; T2 and T3 name later trials. The labels alone do not establish the material, press, inspection scope or approval status. Agree those details before tool manufacture so that a box of attractive samples does not become an accidental production approval.

What must be agreed before the first trial?

Provide the released drawing and CAD revision, exact resin grade and colour, functional dimensions with datums, mating components and the surfaces that matter visually. Identify tests that cannot be assessed from dimensions alone: assembly force, sealing, movement, electrical performance or service-temperature behaviour, where relevant. The product owner must define the actual limits and test conditions.

Record who provides fixtures, who performs each test and who may release production. Agree sample identification by cavity, sample quantities, material conditioning, reporting format and whether samples represent the intended production equipment. There is no universal number of samples or trial rounds suitable for every part.

What should arrive with the sample parts?

The sample package should connect physical parts to evidence: tool and cavity identification, trial date, drawing revision, resin grade and batch, relevant process record and the dimensional results. Include photographs with defect locations and a list of unresolved issues. Keep the inspection samples identifiable after assembly testing; do not mix cavities into an untraceable bag.

Check dimensions under the agreed measurement conditions. A flexible wall can be distorted by a fixture or measuring force; moisture-sensitive plastics may change after conditioning. A result without its method and condition can be difficult to compare with the next trial. Part mass can help monitor consistency but cannot replace dimensional or functional checks.

How should corrections be decided?

Use an issue log with the requirement, observed result, cavity, proposed cause, corrective action, owner and evidence needed to close it. Separate a measurement dispute from a process issue, a tool issue and a changed product requirement. Do not assume that every deviation needs steel machining, or that extra trials prove DFM was skipped.

“Steel safe” means deliberately retaining material at selected tool features so an anticipated correction can remove metal. Whether removal increases or decreases a part dimension depends on the feature and tool geometry. It does not mean all first parts should be undersized, and it cannot make every correction simple. Confirm the correction direction with the tool designer before approving machining.

A cavity-level example: why is an average insufficient?

This is an invented teaching example, not a Nordmould test. Feature 17 is a diameter of 10.00 ± 0.05 mm, giving limits of 9.95–10.05 mm. One illustrative reading from each cavity is shown below.

Cavity	Reading, mm	Individual result
1	10.01	Within limits
2	9.99	Within limits
3	10.08	Outside limits
4	10.00	Within limits

The average is 10.02 mm, but cavity 3 still fails. Hold the affected output for investigation rather than approving all cavities on the average. Four readings do not demonstrate process capability or establish a production sampling plan; agree representative sampling separately.

When can production be released?

Release should identify the approved revision, material, sample report and scope. An open functional failure, missing required evidence or an unaccepted dimensional deviation is a reason to hold the affected release. If a concession is considered, record the exact deviation, authorised decision-maker, quantity or expiry and follow-up action; do not silently change the drawing tolerance.

Schedule the trial, measurement, transport, assembly checks and any correction as separate tasks with owners. Tool access, laboratory availability and the nature of changes determine the programme; a blanket “two rounds” or fixed number of weeks is not a reliable commitment. Use the sample-approval pack to structure the decision, then carry the approved conditions into repeat-order control.

Related preparation and sources

FAI and PPAP explains report scope; the DFM guide covers design preparation. Include the requested sample and test package in your project enquiry.

Protolabs inspection options illustrates that selected-feature inspection, fuller dimensional reporting and capability studies are different deliverables. Its sample sizes, service terms and equipment are its own, not Nordmould commitments.