How to choose a cable assembly manufacturer

1. Quality system: which certificate, and is it real?

Ask which quality management system the manufacturer is certified to, then verify the certificate yourself rather than accepting a PDF.

Always read the scope line. A certificate that covers "distribution of electronic components" does not cover building wire harnesses, even when the company name matches. Check the site too: a certificate for a company's other plant does not cover the one quoting your part. The step-by-step checks for each register are in how to verify supplier certifications.

2. Export and defense compliance

If your cable assembly is defense-related, ask whether the manufacturer is registered with the US State Department's Directorate of Defense Trade Controls (DDTC) under ITAR, and ask for the current registration letter and its expiry. Check the supplier's entity record, CAGE code and exclusions on SAM.gov. Ask how controlled technical data (your drawings) will be stored and who can access it. Also ask whether the supplier accepts the DFARS clauses you flow down, including counterfeit electronic part avoidance (DFARS 252.246-7007 and 252.246-7008), and whether connectors and contacts are bought from their manufacturers or authorized distributors.

Registration with DDTC is not an export license, and a CAGE code only identifies an entity. Neither tells you whether the company is excluded from federal work, which is a separate SAM.gov search.

3. Workmanship: who is trained, to what?

Ask which workmanship standard the shop builds to (for cable and wire harness assemblies, almost always IPC/WHMA-A-620) and at which class. Then ask how many operators and inspectors hold current IPC/WHMA-A-620 training certificates, and at what level. Operator certification is individual and expires (certificates are valid for two years), so the useful answer is a current list, not a statement that the company "is IPC trained".

4. Process control on the crimp

The crimp is where most harness failures begin. A capable manufacturer can describe, without hesitation:

• which applicators and hand tools are used for each terminal, and how their calibration is tracked;
• how crimp height and pull force are checked at set-up and during a run;
• whether crimp cross-section analysis is available for first articles or disputes;
• for automotive work, how the crimp meets the performance specification you call out, such as SAE/USCAR-21.

More detail on what each check proves is in crimp pull testing and crimp height.

5. Test capability

Ask what is tested, on how many parts, and what record is produced. At a minimum, expect 100% continuity testing of production assemblies. Where your drawing requires it, confirm the supplier can also perform insulation resistance and dielectric withstanding voltage (hipot) testing at your voltage and dwell time, and can keep a per-serial record of the results. See cable assembly testing for what each test catches and how to specify it.

6. Traceability and first article

Ask what a single finished assembly can be traced back to: wire lot, terminal and connector date codes, operator, tooling and test record. For aerospace, confirm the manufacturer can produce a first article inspection report to AS9102, and ask when a new FAI is triggered, for example after a drawing revision, a process change or a lapse in production. For automotive parts, the equivalent is a PPAP submission at the level your customer requires.

7. Honest capacity and lead time

Ask what their current lead time is on a comparable part, how they handle long-lead connectors, and what happens when a specified part goes obsolete. A supplier who tells you a connector is on a long lead time before you order is more useful than one who tells you afterwards. See what drives lead time.

8. Engineering support and communication

Ask whether the supplier will review your drawing before quoting, and who you will talk to when a question comes up during the build. A design-for-manufacture review often finds a contact that does not suit the wire size, or a tolerance that cannot be measured on a finished part, before either becomes a nonconformance. How quickly and clearly a supplier answers RFQ questions is a fair preview of how it will handle problems later.

9. Fit with your volumes and mix

A shop set up for long automated runs may struggle with a low-volume, high-mix harness, and a shop built around hand assembly may not be economical at high volume. Ask what a typical order looks like for them, and whether your part is similar. Ask too what processes they subcontract, such as overmolding or cross-sectioning, and how those subcontractors are controlled.

Comparing suppliers side by side

The supplier audit checklist turns these into questions for a site visit.

Common questions

Should I only consider AS9100-certified suppliers?

For flight hardware and most defense work, your customer's requirements usually decide this. For industrial work, ISO 9001 or a strong audit result may be enough. Match the requirement to the part.

How many suppliers should I qualify?

Many buyers qualify at least two for important parts so a capacity or quality problem at one does not stop production. The right number depends on your volumes and how much qualification costs you.

Are online supplier directories a reliable source?

Directories help you find names. Listings are often self-described, so verify any credential a listing shows against its independent record.

What is a red flag in a supplier's answers?

Vague answers to specific questions: a claim of "IPC certification" with no names, a certificate that cannot be found in its register, or a quote with no exceptions for a package that clearly had gaps.

Once you have a shortlist, send each supplier the same package using the RFQ checklist.