Finding a metal parts supplier is easy. Finding one that won’t deliver late, ship defective parts, or disappear after the first order — that takes verification. Based on 15+ years of experience in the industry (from both the buyer and supplier side), here are the essential questions to ask and checks to perform before placing any order.

How do I verify a supplier’s quality management system?

Request a copy of their ISO 9001:2015 certificate — not just a claim on their website. Verify it independently through the certification body’s online database (e.g., UKAS, ANAB, IAF CertSearch). Check that the certificate scope covers manufacturing (not just “trading” or “distribution”), and confirm it hasn’t expired. For medical or aerospace parts, ask for ISO 13485 or AS9100 certifications respectively.

Beyond the paper certificate, ask about their in-process quality control procedures: Do they use SPC (Statistical Process Control)? What CMM equipment do they have? How do they handle non-conforming parts? A good supplier will have clear, documented answers to all of these questions.

Should I visit the factory or use a third-party audit?

For orders over $10,000 or ongoing production relationships, factory verification is strongly recommended. Options in order of thoroughness:

What certifications should I look for?

How can I verify samples before committing to production?

Always request pre-production samples (PPAP or FAI) before authorizing full production. Here’s the verification checklist:

• 1. Dimensional Inspection: Request a CMM (Coordinate Measuring Machine) report comparing every critical dimension to your drawing. Acceptable: all dimensions within tolerance. Unacceptable: “best effort” approximations.
• 2. Material Certification: Request mill test certificates (MTCs) showing chemical composition and mechanical properties. Verify that the material grade matches your specification exactly.
• 3. Surface Finish Verification: For anodized or plated parts, request coating thickness measurements and salt spray test results if corrosion resistance is critical.
• 4. Functional Testing: If your part mates with other components, physically test the fit before approving production — no amount of CMM data replaces a physical fit check.

What payment terms are normal — and what are red flags?

Standard payment terms for international metal parts manufacturing:

• ✅ Normal: 30% deposit with order, 70% balance before shipment (or upon receipt of shipping documents)
• ✅ Acceptable: 50/50 for new relationships or small orders
• ⚠️ Caution: 100% upfront payment (unless a very small order or sample run)
• ❌ Red Flag: Supplier refuses any form of trade assurance, escrow, or letter of credit
• ✅ Good Sign: Supplier offers Net 30 terms after established relationship