Quality documents turn a supplier's promises into checkable evidence. Across a typical order, the documents a buyer should expect follow the production flow: material certificates at incoming, a first article inspection (FAI) at first-off, CMM and dimensional data during and after machining, and compliance documents such as RoHS where the product requires them. This guide lists the documents, explains what each one proves, and shows how to attach the requirements to an RFQ so they arrive with the parts rather than after a dispute.
The Document Set a Serious Supplier Should Produce
A well-run manufacturing order generates a small set of documents, and a serious supplier produces them as routine rather than on request. The set maps to the production stages:
- Material certificates (incoming material verification)
- First article inspection report (first-off validation)
- Dimensional inspection data, including CMM reports where critical dimensions exist
- In-process and final inspection records
- Compliance documents (RoHS, material declarations) where applicable
- Nonconformance and corrective action records when issues occur
The pattern to look for is completeness and traceability. A supplier that can produce the full set for a previous order is running a quality system; one that produces a single generic certificate is not. The list below explains what each document should contain and how to read it.
The document set is also a process signal. A supplier that produces the full set as routine is running a quality system; one that produces documents only on request is treating them as a formality. The buyer should read the documents as the process's output, because the quality system is visible in the records. The routine that is routine is the one that is real.
The document set should be requested in the RFQ, not after the order. The buyer who lists the required documents and their scope in the RFQ gets them priced and produced; the buyer who asks later negotiates the price and waits. The request that is in the RFQ is the one that is met. The document scope belongs with the quote.
First Article Inspection (FAI): What to Ask For
The FAI is the first-part check that verifies the production process produces the part within drawing requirements. Ask for a report that covers:
- The drawing revision being validated
- The material grade and certificate reference
- Each critical dimension with the measured value and the tolerance
- Surface finish readings where specified
- The inspection method used for each dimension
- The inspector and the approval status
An FAI is valuable only if it is tied to the drawing revision and covers the dimensions that matter. A report that lists a few measurements without datum references proves little; a complete FAI lets you release a batch with confidence. The site's first article inspection guide explains the document in more depth.
The FAI's value is in the coverage of the critical dimensions. A first article that measures the functional features—the fits, the sealing surfaces, the mounting pattern—proves the process for the features that matter; one that measures the easy dimensions proves little. The buyer should specify the FAI's coverage with the order, because the first article is the batch's reference. The coverage that is specified is the one that is checked.
The FAI's approval status is the gate. The first article is reviewed, approved, and signed off before the batch runs, and the approval is the batch's release. The buyer should hold the gate, because the batch is produced against the approved first article. The gate that is held is the one that protects.
CMM Reports and Dimensional Data
Coordinate measuring machines (CMM) verify complex geometry and tight tolerances that handheld gauges cannot check reliably. A CMM report typically shows the nominal value, the measured value, the deviation, and the tolerance for each probed feature, often tied to the drawing's datum scheme.
When you request dimensional data, be specific about scope: which dimensions need CMM verification, which can be checked with simpler gauges, and whether you need a full dimensional inspection report (DIR) or a targeted set. The cost of inspection follows the scope, so the requirement belongs in the RFQ rather than being added at the end. If a supplier offers CMM data as an option, ask for a sample report format before the order so you can confirm it matches what your team can use.
The CMM report's datum alignment is the readability test. A report that aligns to the drawing's datums is readable by the buyer's team; one that aligns to a different scheme is data without a reference. The buyer should ask for the sample report and check the datum alignment, because the report's usability follows the alignment. The sample that is readable is the one that is usable.
The dimensional data's scope is a cost and quality balance. Every dimension that is reported adds inspection time, and the buyer should scope the report to the critical features. The scope that is specified is the one that is priced, and the data that is received is the one that is used. The report that is scoped is the one that is useful.
Material Certificates and Traceability
A material certificate (also called a mill test report or MTR) documents the material's identity: grade, heat or lot number, and the chemical and mechanical properties measured at the mill. For machined parts, the certificate is the evidence that the stock was the alloy you specified.
Traceability is the practical requirement to add: the certificate should be traceable to the batch of material used for your order, and your parts should be identifiable to that batch. For most prototype and low-volume projects, a certificate with the heat number and the purchase record is sufficient. For regulated industries, lot-level traceability may require a defined system—confirm the scope with the supplier rather than assuming a generic certificate covers it.
The material certificate's linkage is the traceability. The certificate is tied to the batch of stock used for the order, and the parts are identifiable to that batch; the linkage is what makes the certificate evidence. The buyer should confirm the linkage with the supplier, because a certificate without the batch is a document without a connection. The linkage that is confirmed is the one that is trusted.
The certificate's content is read against the drawing. The grade on the certificate matches the grade on the drawing, and the properties match the requirement; the match is the verification. The buyer should check the certificate against the spec, because the document's value is in the match. The certificate that matches is the one that proves.
Compliance Documents: RoHS and Beyond
Compliance documents answer a different question: does the material and finish meet the restrictions your market requires? RoHS certificates or declarations are common for electronics-adjacent products; REACH communication applies to certain substances in the EU; conflict-minerals and other supply-chain declarations may be required by specific customers.
The practical rule is to name the regulation in the RFQ. "RoHS compliance required" is a request; "RoHS compliance required with declaration for the specific material grades and finishes in this drawing" is a requirement a supplier can price and verify. 6CProto states that RoHS compliance certificates are available on request, so the document can be included in the quote rather than negotiated later.
How to Attach Document Requirements to an RFQ
Documents are cheapest when they are in the RFQ, not added after the quote. Include a short section that states:
- Which documents are required (material certificate, FAI, CMM report, RoHS, etc.)
- The scope of each (which dimensions, which materials, which finishes)
- The format and language required
- Whether documents must accompany shipment or can follow within a defined window
- Which drawing revision the documents must reference
This takes ten minutes and removes the most common failure mode: a supplier that did not know documents were needed until the parts were ready. It also makes price comparison fair, because document scope is a cost component.
What 6CProto Includes by Default
6CProto's stated quality system covers the inspection stages—incoming quality control, first article inspection, in-process control, final control, and outgoing control—and its documentation includes material certificates, FAI reports, CMM inspection reports, dimensional data, RoHS certificates, and functional test results. That means the document set described in this article is part of the standard process rather than a special request.
If you are evaluating a supplier, ask for sample documents before the order: a real FAI, a CMM report, and a material certificate. Request a quote with the document requirements listed, and the response will show both the price and whether the process can deliver what your quality team needs.
The document review after delivery is the acceptance step. The buyer checks the received documents against the RFQ scope—the certificates, the reports, and the records—and accepts or returns them with the parts. The check closes the document loop, because the deliverable includes the paperwork. The buyer who reviews the documents at receipt is the one who closes the loop.
The document retention is part of the quality system. The buyer files the certificates and the reports with the order, and the records are retrievable for the audits and the traceability; the retention is the system's memory. The buyer should keep the document set, because the records are the product's history. The set that is kept is the one that serves.
Conclusion
The quality documents that matter follow the production flow: material certificates at incoming, FAI at first-off, CMM and dimensional data during and after machining, and compliance documents where the market requires them. The discipline is in the scope—name the documents, the dimensions, and the revisions in the RFQ so the evidence arrives with the parts.
The next step is to add a document-requirements section to your standard RFQ and ask the supplier to confirm the scope and provide sample formats before the order. That single change prevents most quality-document surprises.
FAQs
Which quality documents should I request for machined parts?
At minimum, a material certificate, a first article inspection report, and dimensional data for critical dimensions. Add CMM reports for tight or complex geometry and RoHS or other compliance documents where your market requires them.
What is the difference between an FAI and a CMM report?
An FAI is the first-part validation that the production process produces the part within drawing requirements. A CMM report is dimensional data from coordinate measuring, typically used to verify tight or complex features and often included within the FAI.
Should documents be included in the quote price?
Yes, when they are specified in the RFQ. Document scope—which dimensions, which reports, what depth—is a cost component, so define it before quoting to keep comparisons fair and avoid end-of-order additions.
Can I get sample reports before placing an order?
Reasonable suppliers can provide sample formats. Ask for a sample FAI, CMM report, and material certificate; the format reveals whether the documentation will serve your quality team or just fill a folder.