APQP and PPAP: Phases, Elements, and Capability Thresholds

Advanced Product Quality Planning (APQP) and the Production Part Approval Process (PPAP) are the paired frameworks the automotive supply chain uses to bring a new part into production. APQP is the five-phase planning roadmap a supplier follows from concept through launch. PPAP is the documentation package near the end of that roadmap that proves the supplier can consistently manufacture the part to specification. Both are published by the Automotive Industry Action Group (AIAG) as part of its quality core tools, alongside FMEA, MSA, and SPC.1AIAG. Quality Core Tools (APQP – CP – PPAP – FMEA – MSA – SPC)

How the Two Fit Together

APQP produces the evidence. PPAP submits it. A supplier that skips APQP phases and jumps straight to building parts will almost certainly fail its PPAP submission, because the required supporting data (process flow diagrams, control plans, capability studies) simply won’t exist. A supplier that runs a disciplined APQP but never formally submits PPAP documentation still cannot ship production parts.

Because the two are designed to interlock, most automotive purchase orders require both. The planning work builds the data. The submission proves it.

The Five Phases of APQP

Phase 1: Planning

The team defines what the customer needs and what the program must accomplish: engineering specifications, quality targets, reliability goals, cost constraints, and a preliminary timeline. The output is a set of measurable objectives and a project plan covering every validation milestone ahead. Weak planning here front-loads risk into every phase that follows.

Phase 2: Product Design and Development

Engineers translate Phase 1 requirements into detailed drawings and specifications. A Design FMEA (DFMEA) identifies how the product itself could fail and ranks those risks by severity and likelihood before any tooling is cut.2ASQ. FMEA Design reviews confirm the part can actually be manufactured under real-world conditions, not just on paper. Prototype builds and a preliminary bill of materials also come out of this phase.

Phase 3: Process Design and Development

Attention shifts from the part to the production line. Engineers create process flow diagrams that map every step from raw material receipt through final packaging. A Process FMEA (PFMEA) identifies what could go wrong on the floor: a fixture wearing out of tolerance, a heat-treat oven drifting from setpoint.2ASQ. FMEA The control plan is drafted here. It specifies which characteristics are measured, how often, and what happens when a reading falls outside limits.

Phase 4: Product and Process Validation

The supplier runs a trial production lot (sometimes called a significant production run) using the actual tooling, equipment, and operators that will handle full-rate production. Data from this run determines whether the process can hold engineering tolerances consistently. Measurement systems analysis confirms the gauges and instruments are precise and repeatable enough to trust. This phase culminates in the PPAP submission itself.

Phase 5: Feedback and Continuous Improvement

Production is running, but the work isn’t finished. The team monitors delivery performance, scrap rates, warranty returns, and customer feedback. Control plans get updated as the team learns how the process behaves over time. Variation that looked acceptable during the trial run sometimes reveals itself at higher volumes, so statistical monitoring continues indefinitely.

The 18 PPAP Elements

A complete PPAP package contains 18 elements. Not every submission requires all 18 (that depends on the submission level), but the supplier must be able to produce any of them on request.

  1. Design records, including a ballooned drawing with each dimension numbered for cross-reference to inspection results.
  2. Engineering change documents for any authorized changes made after the original design release.
  3. Customer engineering approval, typically required when the supplier is responsible for design.
  4. Design FMEA from Phase 2.
  5. Process flow diagram covering raw material through finished part.
  6. Process FMEA from Phase 3.
  7. Control plan specifying how each critical characteristic is monitored during production.
  8. Measurement systems analysis showing inspection gauges are accurate and repeatable.
  9. Dimensional results mapped against every dimension on the ballooned drawing.
  10. Material and performance test results confirming composition and functional performance meet specifications.
  11. Initial process studies (the Cpk and Ppk capability data from the significant production run).
  12. Qualified laboratory documentation showing any testing lab holds appropriate accreditation.
  13. Appearance approval report, required for parts with cosmetic specifications such as color, texture, or gloss.
  14. Sample product from the trial production run.
  15. Master sample, a reference part retained by both parties to resolve future disputes about appearance or fit.
  16. Checking aids: any fixtures, templates, or go/no-go gauges used to inspect the part.
  17. Customer-specific requirements documentation.
  18. Part Submission Warrant (PSW), the cover sheet summarizing the entire submission. It lists the part number, engineering revision level, part weight, and a declaration regarding restricted or hazardous substances. Signing the PSW is a formal commitment that the parts were produced from a qualified process.

PPAP Submission Levels

Customers assign one of five submission levels based on risk, part complexity, and their confidence in the supplier. The level dictates how much of the 18-element package actually gets sent.

  • Level 1: PSW only. Used for low-risk parts from established suppliers.
  • Level 2: PSW with product samples and limited supporting data.
  • Level 3: PSW with product samples and the complete supporting data package. This is the default level for most submissions.
  • Level 4: PSW plus whatever additional items the customer defines. A catch-all for non-standard situations.
  • Level 5: PSW with product samples and complete supporting data, but everything is reviewed on-site at the supplier’s facility rather than shipped to the customer.

Level 3 is where most suppliers spend their time. New suppliers, new parts, and parts with a history of quality problems tend to get bumped to Level 5. A customer can also escalate a supplier’s default level after a quality escape or failed audit, which is one of the more expensive consequences of a production problem because Level 5 reviews require significant preparation and floor time.

Capability Thresholds Customers Expect

Raw data from the Phase 4 production run gets distilled into process capability indices, primarily Cpk and Ppk. Higher values mean fewer out-of-spec parts.

Under IATF 16949, the standard minimum Cpk for series production is 1.33, which corresponds to roughly 64 defective parts per million. For safety-critical characteristics, the minimum jumps to 1.67, dropping the expected defect rate to about 0.6 parts per million. Some OEMs set thresholds above these floors. Ford, for instance, requires 1.67 across the board for all characteristics, not just safety features.

One distinction catches suppliers off guard. For initial PPAP capability verification, customers generally require Ppk rather than Cpk. Ppk captures long-term performance across all production conditions, while Cpk reflects shorter-term capability. A supplier that submits Cpk data when the customer expected Ppk may be reporting an overly optimistic picture of process stability.

Approval, Interim Approval, or Rejection

After reviewing the submission, the customer assigns one of three dispositions.

Approved means the part meets all requirements and the supplier can begin shipping production quantities.

Interim approval means the part doesn’t fully meet requirements, but the customer will accept shipments for a limited time or quantity while the supplier works on a corrective action plan. The supplier must identify the root cause of the nonconformity and agree to a timeline for resolution. If the issues aren’t resolved before the interim period expires, the supplier must resubmit.

Rejected means the submission failed. No parts can ship. The supplier must correct the deficiencies and resubmit the full package. A rejection can trigger contractual penalties, loss of future business, and in some cases termination of the supply agreement. Suppliers that consistently achieve first-pass approval build a reputation that translates into new program awards. Those that don’t often find themselves stuck at Level 5 indefinitely, absorbing the overhead of on-site reviews on every new part.

When a New PPAP Is Required

An approved PPAP is not permanent. Certain changes to the product or production process reset the approval and require a new submission. The AIAG manual does not require annual resubmission as a blanket rule, though individual customers can impose that requirement through customer-specific addenda.

The following changes generally trigger a resubmission:

  • Engineering changes to the part drawing or specification. The updated Engineering Change Notice must be included in the new package and approved by the customer’s engineering department.
  • Material or sub-supplier changes, including switching to a different raw material grade or a different material supplier even when the specification hasn’t changed.
  • Tooling changes: new tooling, refurbished tooling, additional cavities, or tooling relocated to a different press or machine.
  • Production location changes, including moving the process to a different facility or a different area within the same facility.
  • Process changes to method, equipment, or operating parameters beyond what was approved originally.
  • Capacity changes when required volume exceeds the supplier’s previously verified capacity.

The level of resubmission required for each change type is usually negotiated during quoting or defined in the customer’s supplier quality manual. Some changes warrant a full Level 3 resubmission; others may only require an updated PSW and dimensional results. When in doubt, ask the customer’s supplier quality engineer before making the change. Retroactive approvals are far more painful than proactive ones.

Use Outside Automotive

Although both frameworks originated in automotive, their logic has spread to industries with similar demands for traceability and consistency.

The International Aerospace Quality Group adapted them for aviation, space, and defense through the AS9145 standard. The structure mirrors the automotive version: five phases of quality planning followed by a production part approval gate. Aerospace tolerances are often tighter, lot sizes are smaller, and the regulatory environment adds compliance documentation that doesn’t exist in automotive. AS9145 treats PPAP as an output of APQP, confirming that the production process has demonstrated the ability to consistently meet all requirements at the customer’s demand rate.3IAQG. 9145 Advanced Product Quality Planning and Production Part Approval Process

Medical device manufacturers increasingly use PPAP-style processes to validate incoming components, complementing ISO 13485 and the FDA’s Quality System Regulation (21 CFR 820). The approach is typically streamlined compared to the full 18-element automotive package: suppliers submit a PSW, undergo design and process reviews, provide test samples, and maintain records for auditing. The payoff is risk reduction, since catching a nonconforming component before it enters a device is far cheaper than a corrective action or recall afterward.

How Long Records Must Be Kept

IATF 16949 imposes specific record retention obligations that suppliers often underestimate. PPAP records, tooling ownership documentation, product and process design records, purchase orders, and contracts must be retained for the entire period the product is in active production and service, plus one additional calendar year.1AIAG. Quality Core Tools (APQP – CP – PPAP – FMEA – MSA – SPC) If a part stays in production for eight years and then remains in service for another five, the documentation clock doesn’t start until after that service life ends. Customer-specific requirements can extend the period further, so confirm the retention obligation program by program rather than assuming a single company-wide policy covers everything. ISO 9001 provides the broader quality management framework these obligations sit within.4International Organization for Standardization. ISO 9001:2015 – Quality Management Systems – Requirements

Post navigation