Guides / Choosing a Supplier

What a Shop Certificate Proves and What It Does Not

September 20, 2026

A certification on a shop’s website tells you it passed an audit against a defined standard. It does not tell you the shop is good at 5-axis machining specifically, or that your part will come out right. Knowing what each certification actually verifies helps you decide when to require one and when it is beside the point.

What a certification actually verifies

ISO and industry-specific certifications audit a shop’s documented quality management system: whether procedures exist, whether they are followed, whether nonconformances get tracked and corrected, whether records are kept. They are a process audit, not a skills test. A shop can be certified and mediocre at 5-axis work, and a shop can be excellent at 5-axis work without holding any certification at all, particularly a smaller or newer shop that has not yet gone through the audit process.

The main certifications you will see

Certification	Industry focus	What it adds beyond baseline quality practice
ISO 9001	General manufacturing	Documented quality management system, corrective action process
AS9100	Aerospace and defense	Adds traceability, risk management and configuration control on top of ISO 9001
ISO 13485	Medical devices	Adds requirements for device safety, risk management and regulatory traceability
IATF 16949	Automotive	Adds statistical process control and supplier development requirements
NADCAP	Aerospace special processes	Audits specific processes like heat treat, coating or NDT, not the whole shop

When a certification matters for your part

If your part is going into an aerospace, medical or automotive supply chain, the certification is often not optional. Your own customer, or the regulation governing the end product, may require it as a condition of using the shop at all, regardless of how good the work is otherwise.

When it does not

For a general industrial, robotics, or consumer product part with no regulatory chain behind it, certification is a proxy for process discipline, not a requirement. A shop’s own inspection reports, sample parts and straightforward answers about how it catches errors can tell you as much as a certificate, often for a lower price since certified shops carry the audit cost in their rates.

How to verify a certificate instead of taking it on faith

Ask for the certificate number and the name of the certifying body, then look up the certificate on that body’s public registry. Legitimate certifying bodies maintain searchable databases specifically so this can be checked. A shop that hesitates to provide this information, or whose certificate cannot be found in the registry it claims, is a clear warning sign.

What “certification in progress” actually means

Some shops advertise a certification as “in progress” while pursuing the audit. This is a real and common stage, but it is not the same as being certified, and it should not be treated as equivalent on a bid where certification is a requirement. Ask for an expected completion date and treat the claim as unverified until the certificate exists.

What to ask for on your RFQ

State clearly if your part requires a specific certification as a condition of the order, rather than assuming a shop’s general reputation covers it. If certification is not required, focus questions on the shop’s actual inspection process, equipment list and sample work instead, since that tells you more about fit for a 5-axis part than a certificate that was never designed to measure it.

The short version

A certification proves a documented process passed an audit, not that a shop is good at 5-axis machining. Require the specific certification your supply chain demands, verify it against the issuing body’s registry rather than trusting a logo on a website, and for everything else, judge the shop on its actual work.

See also: aerospace reference page with AS9100 and AS9102 expectations.

See also: aerospace purchase order flow-down clauses a shop must accept.

Frequently asked questions

Keep reading

• How to Choose a 5-Axis Machining Service: Questions to Ask Before You Send a Drawing
• Do You Need an NDA Before Sending a 5-Axis Drawing?