What to Look for in an Inspection Report
For supplier quality engineers and technical buyers receiving machined parts with reports.
A report is evidence that specific characteristics were measured on specific parts under stated conditions. This guide explains how to read that evidence, what it leaves unproven and what to agree before the order.
What a Report Can and Cannot Prove
An inspection report shows that certain characteristics, on certain parts, were measured by a stated method in a stated condition, with the results recorded. Read it in exactly those terms. It says nothing about characteristics that are not listed, pieces that were not measured, or anything that happened afterwards, such as finishing after inspection or damage in transport.
Several different documents are loosely called a report. A first article inspection verifies every drawing characteristic on an initial part; a dimensional or CMM report may cover a selection; a certificate of conformance is a signed statement without data; a material certificate concerns the stock rather than the part. Knowing which one you hold tells you which question it answers.
Related: Quality and inspection
Common Report and Certificate Types
The table compares documents commonly supplied with machined parts. Names and formats vary between industries and companies, so confirm the expected document type and its content when you place the order, rather than relying on the title printed at the top of the page you eventually receive.
| Document | What it shows | What it does not show |
|---|---|---|
| First article inspection (FAI) report | Every drawing characteristic measured on an initial part, often with material and process records; AS9102 defines one widely used format | That later parts or batches conform |
| Dimensional or CMM report | Results for the listed characteristics on the listed parts | Unlisted characteristics, material properties or electrical performance |
| Certificate of conformance | A signed statement that the parts meet the order | Measured values; it relies on records you do not see |
| Material test report, EN 10204 type 2.2 | Compliance declared with results from non-specific, typical production testing | Results for the actual heat or lot supplied |
| Inspection certificate, EN 10204 type 3.1 | Results for the delivered lot, validated by an inspection representative independent of manufacturing | That this lot became your parts, unless traceability is kept |
| Finishing or process certificate | Specification, batch and checks performed by the processor | Dimensions after finishing, unless they were measured |
Certificates follow the material
a type 3.1 certificate belongs to the mill or stockist lot. Ask how the lot or heat number is carried through cutting and machining to your parts.
Header Fields That Tie a Report to Your Parts
Before reading any result, check that the report describes your parts. Most avoidable mismatches appear in the header: an old revision, a different batch or an unstated condition makes every value below it questionable. Check these fields first, and ask for a corrected report rather than accepting the original with a handwritten note.
matching the order and the parts received.
with the quantity inspected against the quantity delivered.
before or after finishing, free state or restrained, and when it was measured.
the instrument or CMM identification and a calibration reference.
the ballooned drawing that the characteristic numbers refer to.
the inspector's name or signature and, where required, a second approval.
Read Each Line Against the Ballooned Drawing
A ballooned drawing numbers every characteristic, and each report line should carry the same number.
Each balloon number matches one report line with limits, value, unit and method — concept illustration
For each line, compare the requirement and limits with the drawing itself, not only with the report's own tolerance column, which can be mistyped. Then check the unit, the actual value, the method and the result. A characteristic reported only as conforming, without a value, is a statement rather than a measurement.
Look for gaps in the numbering. Missing balloons usually mean characteristics that were not measured, sometimes because they could not be reached, and the report should say how those were verified or state that they were not. If you accept a gap, record the reason together with the report so the next lot is checked the same way.
Geometric Tolerances in CMM Reports
Geometric tolerances need more care than sizes. A position tolerance is evaluated in the datum reference frame named in its feature control frame, so the report should state the alignment used, and that alignment should match datums A, B and C on the drawing. A program aligned to convenient faces can produce values that look valid but answer a different question. For a cylindrical tolerance zone, position should be reported as a diametral value, not only as separate X and Y offsets.
Where a tolerance carries a maximum material condition modifier, the permitted position deviation grows as the feature departs from its maximum material size. The report should show the actual size and the bonus applied, otherwise the result cannot be checked. Flatness, profile and runout results should identify the surface evaluated and how many points were measured or scanned.
Related: Antenna mounting structures · Defining waveguide drawing requirements
Point density
a flatness or profile result from a handful of probed points describes those points. If coverage matters, agree a minimum number of points or a scanning method before the order.
Uncertainty, Decision Rules and Results Near a Limit
Every measurement has an uncertainty, and a result close to a tolerance limit may lie on either side of it. ISO 14253-1 sets a default rule that takes uncertainty into account when proving conformance or non-conformance, but many purchase agreements use simpler rules. Decide which applies before the order, especially for features whose tolerance is small compared with the capability of the measuring method.
When your incoming measurement disagrees with the supplier's report, first check that both refer to the same part, revision, characteristic and datum alignment. Then compare part condition, temperature, method and the probe or gauge used. Sharing set-up details usually resolves the difference faster than repeating measurements independently on each side.
Related: Quality and inspection · Surface finishing and dimensional requirements
Agree the Report Before the Order
Most report problems can be prevented at the request-for-quotation stage. A supplier prices inspection time and paperwork, so the required report has to be known before the price is fixed. The items below make the expected evidence explicit and give your receiving inspection a document it can check quickly.
Report type: first article, dimensional, CMM or certificate only, per part number.
Coverage: all characteristics, critical ones only, or a named sampling plan.
Format: your form, the supplier's form or a standard format such as AS9102.
Material and process documents: certificate type and finishing records.
Identification: serial or batch numbering that links each part to its records.
Related Pages
Continue with the closest related part family or guide.
Waveguide Drawing Requirements and Tolerances
Which waveguide features, datums, finish conditions and acceptance checks to define on the drawing before a machining quote.
Specifying Surface Roughness on Machined Parts
Choosing the roughness parameter, placing callouts on functional surfaces, stating the condition and checking the result on received parts.
Surface Finishing and Dimensional Requirements
How finishes change size, how to state before- or after-finish dimensions, threads and masking, and which records show the finished condition.
Questions About Inspection Reports
Is a first article inspection needed for every order?
Normally not. A first article inspection verifies a new part, a new revision or a changed process. Repeat orders of an unchanged part are usually accepted on the agreed routine inspection. Many standards call for a new or partial first article after a design change, a process change or a long production gap, so define those triggers in the order.
Can a certificate of conformance replace a dimensional report?
It can when the order allows it and you have confidence in the supplier's process. A certificate states that the parts conform but carries no measured values, so it gives receiving inspection nothing to compare with the drawing. For critical features or a new supplier, buyers typically ask for measured results on at least those features.
What is the difference between EN 10204 type 3.1 and 3.2?
Both report test results for the specific material delivered. A type 3.1 certificate is validated by the manufacturer's own inspection representative, who is independent of the manufacturing department. A type 3.2 certificate is additionally validated by the purchaser's representative or a third-party inspector named in the order, which takes longer to arrange and is requested when a specification calls for it.
Should the report use our form or the supplier's?
Either can work if the content is agreed. Your own form makes receiving inspection faster and consistent across suppliers, but it has to be sent with the request so the effort is quoted. If the supplier's form is used, check that it carries every header field and characteristic you need before the first delivery.
Discuss Inspection and Report Requirements
Send the drawing, the characteristics you consider critical and the report and certificate types you expect with delivery.
Sales contact (pending)
Name, role and photo to be confirmed
Drawings are optional for an initial discussion.
Start with the information you have; file exchange can be arranged afterward.
Name to be confirmed
Sales, company name to be confirmed
- If you use your own report form, include it.
- A short description of the parts and their acceptance needs is enough to begin.
Project Inquiry
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