How to Audit Suppliers for ISO 9001 & IATF 16949

Table of contents

Why certifications matter (and how they differ)

Buyer takeaway: ISO 9001 demonstrates a functioning QMS; IATF 16949 proves the organization can plan, control and show evidence at the level automotive programs require.

• ISO 9001 defines a general QMS: process approach, risk/opportunity, documented information, internal audits, management review, corrective action.
• IATF 16949 overlays automotive-grade requirements on top of ISO 9001: APQP/PPAP, PFMEA/Control Plan linkage, MSA (GR&R), SPC, product safety, traceability, error-proofing, contingency plans, supplier development, and customer-specific requirements (CSRs).

Core expectations under ISO 9001

• Process map & interactions covering order-to-ship, risks, and KPIs.
• Documented procedures proportional to risk (control of docs/records; nonconforming material; corrective action; training; calibration; purchasing).
• Internal audit program + management review minutes with actions.
• Competence & training records for operators, inspectors, programmers.
• Calibration & verification of gauges, CMMs, pressure/leak rigs; traceable to national standards.
• Nonconforming product control: identification, segregation, disposition (rework, repair, scrap) with re-inspection.
• Corrective action (8D/A3) with root-cause tools (5-Why, Ishikawa).

What IATF 16949 adds for automotive

• APQP phases with gateways; PPAP submission at agreed level (often Level 3).
• Linkage trio: PFMEA → Control Plan → Work instructions (same SC/CC flow-down).
• MSA: Gauge R&R for measuring SC/CC features; bias/linearity/stability where needed.
• SPC: capability Cp/Cpk on key characteristics; ongoing control charts at a rational frequency.
• Product safety & traceability: heat/batch to serial, FIFO control, labelling rules.
• Contingency & change management: documented contingency plans; ECR/ECO and deviation/waiver process.
• Error-proofing (poka-yoke) and preventive maintenance with OEE or similar.
• Supplier management: selection/monitoring, cascading requirements, incoming inspection strategy.
• Customer-specific requirements (CSRs) acknowledged and integrated.

Foundry-specific controls buyers should see

• Melting & metallurgy: OES chemistry per heat; ladle/furnace logs; chill-depth or microstructure checks; hardness trends.
• Moulding/core system: AFS GFN/clay/moisture/compactability/LOI windows; core sand/binder ratios; coating DFT control; drying parameters.
• Gating/risering: simulation or standard rules; try-out records; yield & defect Pareto.
• Heat treatment (if any): cycle charts, quench/temper controls, load maps; sample mechanical tests.
• Repairs policy: welding/impregnation criteria, approvals, and re-inspection.
• Identification & traceability: heat/batch on cast/label; casting date/shift if required.
• Final inspection & cleanliness: shot-blast media control, visual criteria, burr/sand inclusion/burn-on acceptance.

Useful deep dives on your site:

• PPAP for Iron Castings
• Foundry Quality KPIs
• Incoming Core Sand & Binder QC

Machine-shop controls that protect quality

• Process flow/routers with tool lists, offsets, and critical operations.
• Program control: DNC/version control; approval before release; back-ups.
• First-piece & in-process inspection plans; check frequency by risk.
• Gauging: calibrated micrometers, bore/air gauges, threaded plug rings; CMM/3D scan coverage for complex geometry. (See CMM vs 3D Scanning if live.)
• MSA completed for gauges measuring SC/CC features.
• Coolant & chips: filtration, concentration control, cleanliness specs (important for sealing faces/leak tests).
• Segregation of nonconforming parts; red tag & locked location.
• Packaging & preservation: VCI/oil, caps for bores/threads, corrosion checks.

Evidence pack: documents to request

Use this list at RFQ/onboarding. Ask for what is relevant to your part.

Certificates & scope

• ISO 9001 certificate; IATF 16949 certificate (if applicable); scope and sites.

Core QMS

• Process map; key procedures (NCR/CA, calibration, training, supplier control).
• Latest internal audit summary + management review actions.

APQP/PPAP (if automotive-style)

• Process Flow, PFMEA, Control Plan (matching SC/CC).
• MSA studies (GR&R) for gauges on SC/CC.
• Dimensional results (CMM/scan), material & HT certs, capability studies (Cp/Cpk) if available.
• SPC examples and reaction plans.

Foundry-specific

• AFS sand control logs; chemistry & hardness trends; coating DFT logs; defect Pareto.
• Weld/repair standard and approvals.

Machining

• First-piece approval record; in-process check sheets; gauge calibration list.

On-site/audit day checklist

• Walk order-to-ship: incoming → melt/mould → pour → clean → machine → final.
• Verify traceability from heat/batch to finished label.
• Spot-check calibration stickers and master artifacts.
• Ask operators how nonconforming parts are handled—see the cage.
• Review last 3 months of KPIs and top corrective actions; check effectiveness.
• Confirm contingency plans (power outage, furnace failure, key mold line downtime).
• For machining, observe first-article process and tool preset/offset control.

KPIs & acceptance targets

Typical buyer targets (tune to your program):

• OTD ≥ 95%
• PPM/DPPM targets by part family (see Foundry Quality KPIs page)
• Cp/Cpk ≥ 1.33 on SC/CC during capability runs (unless otherwise agreed)
• Leak/NDT first-pass yield ≥ 98–99% where applicable

What YBmetal delivers

YB Metal Solution operates a documented QMS aligned with ISO 9001 and delivers APQP/PPAP artifacts when required (up to Level 3), including PFMEA/Control Plan linkage, MSA on critical gauges, SPC on key features, and full chemical/mechanical traceability. If your program mandates particular certificates or CSRs, tell us in /rfq—we’ll confirm scope for our plant and key sub-suppliers.