How to Evaluate a Manufacturing Partner: A Practical Checklist

Choosing the wrong offshore manufacturer costs more than money — it costs months of rework, damaged customer relationships, and sometimes your competitive advantage. Yet most US companies evaluate suppliers based on a quote comparison and a factory tour. That's like hiring a surgeon based on their office décor.

This checklist is what we use internally at Dewin to vet every facility in our network. It's organized into seven categories, scored on a pass/fail and weighted scoring system. Use it as-is or adapt it to your industry requirements.

Category 1: Quality Management System (25% weight)

Quality isn't about catching defects — it's about preventing them. A mature quality system is the single strongest predictor of manufacturing success.

Must-Have (Pass/Fail)

• ISO 9001:2015 certification — From an accredited registrar (check ANAB, UKAS, or IAF accreditation). Not just "working toward" — actually certified.
• Documented quality procedures — Ask to see their quality manual table of contents. It should cover incoming inspection, in-process control, final inspection, nonconformance handling, corrective action (CAPA), and calibration.
• Calibrated inspection equipment — Request calibration certificates for their CMM, micrometers, calipers, and gauges. Calibration should be traceable to NIST or equivalent national standard.

Scored Criteria

• Industry-specific certifications: IATF 16949 (automotive), ISO 13485 (medical), AS9100D (aerospace), IECQ (electronics). Score: +3 per relevant cert.
• SPC implementation: Do they use statistical process control on critical dimensions? Ask for sample Xbar-R charts. Score: +2 if systematic, +1 if ad hoc.
• Inspection capability: CMM (Zeiss, Hexagon, Mitutoyo), optical comparator, profilometer, hardness tester, spectrometer (material verification). Score: +1 per capability.
• Reject rate data: Ask for their internal reject rate and customer return rate. Good shops run <0.5% internal, <0.1% customer returns. Score: +3 if they track and share this openly.
• CAPA system: How do they handle complaints? Request an example 8D report (redacted). Score: +2 for systematic 8D, +1 for informal process.

Category 2: Manufacturing Capability (20% weight)

Must-Have

• Equipment list with specifications — Brand, model, year, working envelope, accuracy. No reputable shop refuses to share this.
• Capability match: Can they actually make your parts? Match your part requirements (size, tolerance, material, finish) against their equipment specs.

Scored Criteria

• Equipment age and condition: Average age <5 years: +3. 5–10 years: +2. >10 years: +1. Look for preventive maintenance logs.
• Capacity utilization: 60–80% is ideal. Under 50% suggests financial trouble. Over 90% means your jobs will queue. Ask directly: "What's your current utilization?"
• In-house capabilities breadth: The more processes under one roof (cutting, machining, welding, finishing, assembly), the fewer handoffs and the more control. Score: +1 per in-house capability.
• Engineering support: Do they have design engineers who can do DFM reviews? CAM programmers? A solid engineering team catches problems before they become expensive. Score: +3 if strong, +1 if basic.
• Sample parts: Request sample parts similar to yours. Evaluate them yourself — dimensions, finish quality, packaging. Nothing tells you more about a shop than their actual output.

Category 3: Financial Stability (15% weight)

A supplier that goes bankrupt mid-order takes your tooling, your deposits, and your production schedule with them. Financial diligence isn't optional.

• Years in business: >10 years: +3. 5–10: +2. 2–5: +1. <2: flag for extra scrutiny.
• Revenue trend: Ask about revenue growth over the past 3 years. Stable or growing is good. Declining warrants investigation.
• Customer concentration: If one customer represents >40% of revenue, that's a risk. If that customer leaves, capacity and attention to your orders may suffer.
• Workforce stability: High turnover (>20% annual) in a manufacturing context means constant retraining, quality variation, and delivery risk.
• Facility ownership vs. lease: Owned facilities suggest commitment and stability. Short-term leases can indicate precarious finances or flight risk.
• Creditworthiness: For significant tooling investments, request a D&B report (Dun & Bradstreet) or equivalent local credit check.

Category 4: Communication and Responsiveness (15% weight)

The factory with the best machines and lowest price is worthless if you can't get a straight answer about delivery dates. Communication capability predicts 80% of the relationship quality.

• Response time test: Send a technical question by email. If they respond within 24 hours with a substantive answer (not just "received, will reply later"), score +3. 24–48 hours: +2. >48 hours: red flag.
• English capability: Can their engineering and quality contacts communicate technical details in English without a translator? If the sales team is fluent but engineering can't communicate, you'll hit problems during production. Score: +3 if engineering is fluent, +1 if sales-only.
• Project management: Do they assign a dedicated PM to your account? Do they provide regular status updates without being asked? Score: +3 for proactive, +1 for reactive.
• Problem transparency: The most important question: "Tell me about a time a production run went wrong. What happened and how did you fix it?" Honest answers about failures reveal character. Claiming "we never have problems" is a red flag.
• Digital tools: Do they use shared project trackers, cloud-based file sharing, or ERP-connected portals? Modern communication tools indicate operational maturity.

Category 5: IP and Confidentiality Protection (10% weight)

• NDA willingness: Will they sign your NDA without pushback? Score: +2. If they propose their own (reasonable) alternative: +1. Refusal: fail.
• Physical security: Visitor logs, restricted areas, camera systems, badge access. Look for these during factory visits. Score: +2 for thorough, +1 for basic.
• IT security: Ask about file handling procedures. Are your drawings stored on secured servers? Who has access? Is there a data retention/destruction policy?
• Mold ownership documentation: Will they provide stamped mold ownership certificates? Will they release molds if you terminate the relationship? Get this in writing before ordering tooling. Score: +3 for clear policy, 0 if vague.
• Customer segregation: Do they serve your direct competitors? If yes, what controls prevent cross-contamination of technical information?

Category 6: Logistics and Delivery (10% weight)

• On-time delivery rate: Ask for data. >95%: +3. 90–95%: +2. <90%: red flag. If they can't provide data, assume it's bad.
• Packaging capability: Do they design packaging for export shipping? Ask for photos of typical export packaging. Score: +2 for custom packaging with shock/moisture protection.
• Shipping experience: Do they handle FOB, CIF, or DDP terms? Experienced exporters understand Incoterms and customs documentation. Score: +2 for DDP experience, +1 for FOB only.
• Proximity to port: <50km to a major port: +2. 50–200km: +1. >200km: inland freight adds cost and time. Vietnam's key manufacturing zones (HCMC, Hai Phong, Da Nang) are all port-adjacent.
• Lead time reliability: Request references and ask specifically about delivery performance. The quote lead time vs actual lead time gap reveals a lot.

Category 7: Sustainability and Compliance (5% weight)

• Environmental compliance: ISO 14001, local environmental permits, waste disposal documentation. Increasingly required for supply chain due diligence.
• Social compliance: SA8000, BSCI, SEDEX/SMETA audit reports. Required by many US retailers and OEMs.
• RoHS/REACH compliance: Can they provide material declarations and test reports? Score: +2 for proactive compliance program.
• Conflict minerals: CMRT (Conflict Minerals Reporting Template) capability for products containing tin, tantalum, tungsten, or gold.

The Scoring System

After evaluating all categories:

Red Flags That Should Stop the Evaluation

Any of these is an immediate disqualification, regardless of score:

1. Refuses factory visit — No legitimate manufacturer blocks customer visits.
2. Can't produce material certificates — If they can't trace materials, they can't guarantee your parts.
3. No quality records — A shop without inspection records isn't inspecting.
4. Pressure to skip first article — "Just trust us, we'll get it right" is the most expensive sentence in manufacturing.
5. Price way below market — 10–15% below competitors is competition. 40% below means they're cutting corners you can't see yet (cheap material, skipped heat treat, untrained operators).
6. Ownership/management opacity — If you can't determine who owns and runs the company, walk away.
7. Child labor or safety violations — Zero tolerance. Full stop.

The Trial Order: Your Real Evaluation

No checklist replaces actual manufacturing experience. After selecting a supplier, start with a trial order:

• 5–10 piece first article with full dimensional inspection report
• 50–200 piece pilot run to evaluate process stability
• Full production only after pilot meets all quality criteria

Budget 8–12 weeks for the trial process. It's the cheapest insurance you'll ever buy. Companies that skip trial orders save 8 weeks — and often lose 6 months fixing quality disasters.

How Dewin Handles Supplier Evaluation

Every factory in our network has passed this evaluation — plus on-site audits by our quality engineering team. We re-evaluate annually and after any major quality event. When you work with Dewin, you're working with suppliers we've already qualified and continue to monitor.