FAI & PPAP checklist for metal processing suppliers

When awarding work to a metal processor, procurement and engineering teams need a focused, actionable framework to evaluate quality systems. This FAI & PPAP checklist for metal processing suppliers lays out what to review in quality manuals, inspection plans, capability studies, metrology assets, first‑piece approvals and nonconformance loops so you can make a defensible go/no‑go decision.

Executive summary: FAI & PPAP checklist for metal processing suppliers

This executive summary outlines the buyer’s decision flow: what minimal evidence you should request, which red flags require escalation, and how to combine document reviews with short audits or sample testing. Use this FAI & PPAP checklist for metal processing suppliers as your quick reference before diving into the detailed checklist below.

• Ask for the supplier’s quality manual, current inspection plans, recent capability reports, and examples of FAI/PPAP submissions.
• Verify metrology assets and gauge R&R documentation where dimensional control is critical.
• Confirm nonconformance and corrective action processes (8D/CAPA) and look for supplier escapes or repeated issues.
• Score findings against a pre-defined rubric to determine approval, conditional approval, or rejection.

Why require FAI, PPAP or both for metal parts?

First Article Inspection (FAI) and Production Part Approval Process (PPAP) serve overlapping but distinct buyer needs. Use First Article (FAI) and PPAP checklist for metal suppliers to decide whether you need dimensional proof-of-conformance, process stability data, or both. FAI focuses on first-piece verification against drawings and BOMs; PPAP brings process capability, control plans, and evidence for sustained production quality.

Require FAI when design validation or change control is the priority. Require PPAP when you need documented, repeatable evidence that the supplier’s process can produce compliant parts at volume.

When to require First Article Inspection vs PPAP

Make the choice between FAI and PPAP based on part criticality, production volume, and change history. Consider the following rules of thumb:

• FAI: new designs, engineering revisions, or new suppliers for low-to-moderate volume runs.
• PPAP: high-volume production, safety‑critical components, or where process variation directly affects function.
• Both: when launching a critical part with complex tolerances and long-term supplier relationship intent.

For guidance when drafting supplier requirements, refer to FAI vs PPAP for metal fabricators: when to require each and what deliverables (inspection reports, dimensional data, control plans) to request — it outlines which deliverables to request for each scenario.

Variants and hybrid approaches

In many programs a hybrid path makes sense: require an initial FAI plus a limited PPAP submission (e.g., PPAP Level 3 with key capability studies) after a short production run. Use the Metal processing supplier quality checklist: FAI, PPAP, inspection & metrology approach to outline hybrid requirements.

What to review in the supplier quality manual

The quality manual is the high-level map of how the supplier runs its quality system. When reviewing it, confirm the manual addresses document control, change management, supplier controls, inspection planning, calibration, and nonconformance handling. Look for references to standards such as ISO 9001 or IATF 16949 where relevant.

Key checklist items:

• Documented inspection plan development and approval authorities.
• Calibration program and traceability to national standards.
• Control plan and reaction plan for out-of-tolerance detections.
• Supplier’s approach to subcontracted processes and special processes.

Inspection plans: sampling plans vs 100% inspection

Deciding between sampling plans and 100% inspection is a fundamental tradeoff between cost and risk. The right approach depends on defect impact, process capability, and inspection throughput.

For critical safety features or where downstream rework is costly, 100% inspection may be justified. For high‑capability processes with solid Cp/Cpk metrics and validated inspection systems, statistically designed sampling plans (e.g., ANSI/ASQ Z1.4 or AQL-based plans) reduce inspection burden while maintaining acceptable risk.

Sampling plans vs 100% inspection for stamped, machined and fabricated metal parts — tradeoffs, CMM/optical capacity, and audit checklist

When evaluating a supplier, use the clause Sampling plans vs 100% inspection for stamped, machined and fabricated metal parts — tradeoffs, CMM/optical capacity, and audit checklist to determine whether throughput or defect containment should drive the decision. Machined parts with tight critical dimensions often require higher sampling or 100% CMM inspection; stamped parts with well‑controlled dies may be adequately covered by sampling plus periodic Cpk checks.

Metrology & inspection capability assessment

Inspect not just the instruments but the metrology program. Confirm traceability of standards, calibration intervals, environmental controls, and operator training. Ask for recent calibration certificates and evidence that critical gages are on calibration schedules.

Also confirm the supplier’s CMM, optical inspection systems, fixturing capacity and throughput — having a single CMM is not enough if inspection becomes a production bottleneck. Assess whether the supplier’s inspection capacity aligns with your production volumes — having a CMM is important, but having enough CMMs, fixtures, and trained operators to meet throughput is equally critical.

Gage R&R readiness and gauge selection

Measurement System Analysis (Gage R&R) & gauge selection readiness is a cornerstone of trust in inspection data. Request recent GR&R studies for critical dimensions and review the study design, sample size, and analysis of repeatability and reproducibility. Poor GR&R invalidates capability studies and undermines both FAI and PPAP submissions.

• Verify GR&R percent contribution to total variation falls within your acceptance criteria.
• Check that gauges used are appropriate for the tolerance band — avoid using coarse gages to measure fine tolerances.
• Ensure gauge selection includes consideration for part fixturing and operator ergonomics.

CMM, optical systems, fixturing and throughput checks

Review the supplier’s CMM capacity, touchscreen or optical inspection systems, and the availability of dedicated fixtures. Ask for takt‑time estimates: how many parts per hour can the metrology lab reliably measure without creating bottlenecks?

Key questions to ask:

• Are fixtures repeatable and documented? Are they part‑specific or universal?
• Is there spare capacity to handle rushes or changes in inspection load?
• Does the supplier have automated reporting that integrates with your data needs?

First-piece approval (FAI) process and deliverables

The FAI package should clearly map part features to inspection results, BOM verification, and any deviations. A complete FAI submission typically includes dimensional inspection reports, material certifications where needed, photographic evidence of fixtures and setups, and signed approvals from responsible engineers.

Make sure FAI deliverables are timestamped and include the production setup conditions. If fixtures or programs used for the FAI differ from production, require justification and a plan to align them before full production.

PPAP submission levels, expected documentation and data

PPAP levels define the depth of documentation from a minimal evidence set to full submission with supporting data. Common expectations include control plans, FMEA, process flow diagrams, capability studies (Cp/Cpk), and measured results. Require a PPAP Level that matches part criticality — higher levels for safety-critical or high-volume parts.

Request examples of recent PPAP packages the supplier has completed for similar parts. Validate that Cpk analyses use valid data and that measurement systems behind those analyses were stable.

Process capability studies (Cp, Cpk) & capability acceptance

Process capability numbers quantify the supplier’s ability to meet tolerances. When reviewing Cp and Cpk reports, check the dataset, sample size, and time span. Short data windows can mask special causes; studies should include stable production runs representative of expected volume.

Set acceptance thresholds appropriate to your risk tolerance: many programs accept Cpk > 1.33 for non-critical features and > 1.67 for critical features, but buyer-specific criteria should be documented in the control plan.

Nonconformance handling, 8D/CAPA loops and supplier escapes

Robust corrective action is critical. Review the supplier’s nonconformance handling, corrective action (8D/CAPA) and supplier escape prevention processes for timeliness, root cause depth, containment effectiveness, and preventive measures. Ask to see closed 8D reports for issues similar in type or severity to the risks of your part.

Pay attention to supplier escapes — incidents where nonconforming parts reached customers. Repeated escapes, inconsistent root causes, or superficial corrective actions are strong disqualifiers.

Sampling plan design: practical tradeoffs by process (stamped, machined, fabricated)

Design sampling plans that reflect process behavior. Stamped parts with die‑controlled features may need periodic dimensional checks and more frequent tool monitoring; machined parts require dimensional capability tracking and tool wear control; fabricated assemblies often need weld inspection and fit checks.

Adapt plans over time: begin with conservative sampling during initial production, then relax frequency if capability metrics remain stable and metrology systems are validated.

Audit checklist: what to verify onsite or via remote review

An audit should verify that documented processes are practiced on the shop floor. If you need a short checklist, see How to audit a metal processor’s quality manual, inspection plans, capability studies and first‑piece approvals before awarding work — it maps key documents to on-floor checkpoints for fast validation.

1. Walk the production cell to confirm fixture setups match FAI/PPAP documentation.
2. Inspect metrology environment for temperature/humidity controls and traceable calibration records.
3. Interview operators on inspection routines and escalation paths for nonconformances.
4. Review recent nonconformance logs and closed CAPAs.

For remote reviews, request live video of setups, scanned calibration certificates, and screen-shared metrology reports. Validate authenticity by cross-referencing timestamps and serial numbers.

Scoring rubric, risk matrix and go/no-go decision

Create a weighted scoring rubric that translates findings into a clear decision. Typical categories and suggested weights include:

• Quality system & documentation (20%)
• Metrology and measurement reliability (20%)
• Process capability (20%)
• Nonconformance handling (15%)
• Throughput and capacity (10%)
• Cost / commercial alignment (15%)

Define thresholds for automatic approval, conditional approval with corrective actions, or rejection. Use the risk matrix to escalate items that affect safety or regulatory compliance.

Case studies: approvals, rejections and lessons learned

Real examples help calibrate expectations. Common lessons include:

• A supplier with strong documentation but weak GR&R was unable to substantiate Cp/Cpk claims — conditional approval with mandatory GR&R repeat was effective.
• A processor with limited CMM throughput underestimated inspection lead times, causing delivery issues — approval after capacity commitments and fixture investment.
• Supplier escapes tied to subcontracted heat‑treat processes required co‑audits of the heat‑treater before full approval could be granted.

Appendix: templates, glossary and quick-reference checklist

Include ready-to-use templates for FAI submissions, PPAP checklists, GR&R request forms, and audit scorecards. A concise glossary helps align terms such as Cp/Cpk, GR&R, control plan, and nonconformance escape.

Quick checklist (one‑page):

• Quality manual present and up-to-date
• Inspection plans and control plans documented
• Metrology assets calibrated and traceable
• Recent GR&R for critical dimensions
• FAI or PPAP submission with supporting data
• Process capability reports with valid measurement systems
• Documented 8D/CAPA process and closed examples
• Capacity confirmation for inspection throughput
• Scoring rubric applied and decision recorded

Using the Supplier quality assessment checklist for metal fabricators (FAI / PPAP) in the appendix gives procurement and engineering teams a practical tool to standardize evaluations across suppliers and parts.

For next steps, tailor the checklist to your program by assigning acceptance thresholds, defining required PPAP levels by part class, and mapping escalation paths for critical findings. A standardized approach reduces onboarding time, reduces surprises in production, and helps secure consistent part quality.