Home / Guides / Quality

First article inspection: what to ask for and how to read the report

July 28, 2026

A first article is the moment where a drawing stops being a document and becomes parts. It is also the cheapest place in the whole process to find a problem. Treating it as a formality is how buyers end up with 500 pieces that are consistently wrong.

What a first article actually is

One or a few pieces, produced with the production setup, measured against every dimension on the drawing, and reported. The report is what you are buying. Its job is to let you say yes or no with evidence, not by looking at a photo.

Three conditions make it meaningful:

1. Same process as production. Same fixture, same program, same machine family, same material lot where possible. A hand made sample proves nothing about the batch.
2. Ballooned drawing. Every dimension numbered, every number appearing in the report. Without this, “all dimensions in tolerance” is an opinion.
3. Named instruments. Which dimension was measured with what. A position callout measured with calipers is not a measurement.

What belongs in the report

• Part number, revision and date. Revision control is where most disputes start
• Every dimension, its nominal, its tolerance, the actual measured value and a pass or fail
• The instrument used for each measurement, or at least for the critical ones
• Material certificate, if you asked for traceability
• Finish certificate, where a coating is specified
• Photographs of the part, including any area where you flagged a concern
• A note of any deviation, with the shop’s proposal

A report that says pass for every line with no actual values is not a report. Ask for the numbers. Real measurements scatter around nominal, and seeing that scatter tells you how much margin the process has.

Reading the numbers rather than the verdicts

Look at where the actual values sit inside the tolerance band. Three patterns matter:

Comfortably centred. The process has room. Production will be stable.

Consistently near one limit. The process is capable but biased. It will drift over the batch as the tool wears. Ask the shop whether it intends to offset the program.

Just inside on a critical feature. Treat this as a warning even though it passes. Ask what the process capability is and whether the feature is checked in process or only at the end.

If a feature is critical and the shop measured one piece, ask for five. The spread across five pieces tells you far more than the position of one.

Agreeing the rules before production

Settle four things in writing before the purchase order. It takes one email.

• What constitutes a first article here, including quantity and report format
• How long you will take to approve. Your approval time sits inside the lead time and shops plan around it
• What happens to a failed dimension. Correct and re-submit, request a deviation, or stop
• Whether production may start before approval. Shops often ask to start in parallel to hold a date. That is a risk decision and it should be yours, not an assumption

When a dimension comes back out of tolerance

Do not start with blame. Start with three questions:

1. Is the feature functional? Sometimes the answer is that the tolerance was inherited and the part is fine. A concession on paper is faster and cheaper than rework.
2. Is the drawing internally consistent? Conflicting dimensions and an unclear datum scheme cause more failures than bad machining.
3. Is it the process or the measurement? Ask what instrument was used and, on tight features, whether the measurement was repeated.

A shop that answers these calmly with data is a shop worth keeping. A shop that immediately offers a discount to make the problem go away is telling you what the next batch will look like.

Keep the approved article

Ask for the approved first article to be retained at the shop as a reference, and keep one yourself if you can. When a later batch is questioned, having a physical reference that both sides accepted is worth more than any email thread.

A first article package that works

For commercial parts, this is the package worth asking for by name. It costs a shop an hour or two and removes most of the arguments that come later.

• Ballooned drawing with every dimension numbered
• Dimensional report listing nominal, tolerance, actual and pass or fail per balloon
• Three pieces measured rather than one, so you can see the spread
• Material certificate where traceability was requested
• Finish certificate where a coating was specified
• Photographs of each face, plus any feature you flagged
• A process note: which machine, which fixture, how many operations

Ask for it as a PDF with the measurements in a table you can read, not as a photograph of a handwritten sheet.

What to check first when it arrives

Work through it in this order and you will find most problems in five minutes:

1. Revision on the report matches the revision you released. More failures start here than anywhere else.
2. Every balloon has a number. Blanks are not passes.
3. Critical features first. Look at the actual values, not the verdicts.
4. Spread across the three pieces. Tight spread means a controlled process. Wide spread inside tolerance means the next batch is a coin toss.
5. Anything measured with the wrong instrument. A position callout checked with calipers is a flag, not a measurement.

The guides on tolerances and on vetting a shop cover the two things that decide whether your first article goes well before it is ever machined. When your drawing is ready, send it here and say in the request what inspection you will want, so the shops quote it in.

Questions we get on this

Keep reading

• CMM, height gauge or optical comparator: choosing the check for each feature
• How to vet a machine shop before you place the first order