Practical Guide to PPAP (Production Part Approval Process) —— Key Points from Submission to Approval

1. What Problems Does PPAP Solve

In the supply chain of the automotive and parts industry, there is a recurring scenario: low qualification rates for the first delivery of new parts, repeated adjustments on the production line, and significant quality fluctuations between batches. The root of these problems often lies not in the mass production phase but in the lack of or superficial "pre-production approval process."

PPAP (Production Part Approval Process) is a tool specifically designed to address this issue. It is one of the five core tools of IATF 16949, published by AIAG (Automotive Industry Action Group). The core objective of PPAP is to produce a batch of samples at the production rate using formal production tools and processes, and to prove through a systematic chain of evidence that the supplier has the capability to consistently produce conforming products.

PPAP is not a one-time "form filling task," but a verification checkpoint that connects Advanced Product Quality Planning (APQP) with mass production. It answers a critical question: Can the requirements specified in the drawings and specifications be consistently reproduced on the actual production line?

2. The 18 Submission Elements of PPAP

The complete evidence chain of PPAP consists of 18 elements, and companies need to deliver the corresponding depth of documentation based on the submission level required by the customer. These 18 elements are divided into three categories:

First Category: Design and Process Definition (Elements 1-5)

1. Design Record — including product drawings, models, and all engineering change records
2. Engineering Change Documents — changes not formally approved by the customer must be separately marked
3. Design FMEA (DFMEA) — risk analysis of product design failures
4. Process Flow Diagram — graphical description of manufacturing and inspection processes
5. Process FMEA (PFMEA) — risk analysis and control measures for manufacturing processes

Second Category: Verification and Validation (Elements 6-13) 6. Control Plan (CP) — inspection and control plan for the production line based on PFMEA 7. Measurement System Analysis (MSA) — evaluation of gauges for GR&R, bias, linearity, etc. 8. Full Dimensional Measurement Results — dimensional verification of each characteristic according to the drawings 9. Material/Performance Test Results — material reports, functional tests, durability tests, etc. 10. Initial Process Capability Study (Cpk/Ppk) — process capability calculated using at least 100 pieces of continuous production data 11. Laboratory Accreditation — ISO 17025 or equivalent accreditation for in-house or outsourced labs 12. Appearance Approval Report (AAR) — visual inspection of appearance parts according to customer standards 13. Production Part Samples — retain samples approved by the customer as a reference

Third Category: Traceability and Records (Elements 14-18) 14. Standard Samples — standard parts used for daily production line comparisons 15. Inspection Aids — verification records for gauges, fixtures, and measuring instruments 16. Customer Special Requirements — evidence of meeting special terms for the product 17. Part Submission Warrant (PSW) — the final summary document of PPAP, signed by the supplier as a commitment 18. Bulk Material Requirements Checklist — applicable only to non-discrete materials such as chemicals and powders

3. Submission Levels and Approval Status

PPAP defines five submission levels, and suppliers can choose based on customer requirements:

• Level 1: Submit only the PSW — suitable for changes in mature parts that have been fully validated
• Level 2: Submit PSW + product samples + some supporting data — suitable for general changes
• Level 3 (most commonly used): Submit PSW + all 18 elements — the default level for new parts or significant changes
• Level 4: Submit PSW + customer-specified items — for special requirement scenarios
• Level 5: Submit PSW + all elements + supplier site audit — for high-risk parts

After submission, the customer can provide one of five approval statuses:

Approved — the part can enter mass production. Provisional Approval — there are deviations but they are acceptable, with a specified rectification deadline. Rejected — not passed, requiring rework and resubmission. Additionally, there are "Approved for Shipment" (customer retains the right to reject) and "Customer Waives PPAP Requirement" (rarely used).

A common misconception: thinking that "Provisional Approval" is the same as "Approval." In reality, provisional approval typically comes with a clear rectification period (e.g., 60 days), and failure to close all deviations within this period will result in rejection.

4. Typical Scenario: PPAP Submission Process for New Parts

Using an example of a machining company receiving a Level 3 PPAP requirement for a new part:

Week 1: Complete design review and update DFMEA, develop process flow diagrams and draft PFMEA. Week 2: Complete the compilation of the control plan (CP), plan SPC monitoring points for critical dimensions. Week 3: Produce 150 pieces at the formal production rate (keep 50 pieces as backup) — must use production tools, gauges, and operators. Week 4: Send for full dimensional measurement and material testing, complete MSA and initial capability Cpk calculation. Week 5: Summarize all evidence, fill out the PSW, and submit to the customer.

A key checkpoint: Before submission, ask yourself — does each failure mode in the PFMEA have a corresponding control measure in the control plan? Have all gauges in the control plan completed MSA? Many one-time rejections are due to these two interrelated issues.

5. Key Application Points and Common Misconceptions

Applicable Scenarios: PPAP is primarily used in the automotive and parts industry but is gradually expanding to other sectors requiring strict supply chain control, such as aerospace, electronics manufacturing, and medical devices. Typical triggering conditions include: new part production, design changes, process changes, supplier changes, factory location changes, or resuming production after a shutdown of more than one year.

Usage Precautions:

• PPAP samples must be produced at the production rate, using production tools and in the production environment; they cannot be replaced by "optimized conditions" or handcrafted samples.
• The initial process capability study (Element 10) requires at least 100 pieces of continuous production data, and the process must be in a statistically controlled state.
• The signature on the PSW has contractual effect, and the supplier must be responsible for the authenticity of the submitted data.

Five Common Misconceptions:

1. "PPAP is just filling out the PSW" — in fact, all 18 elements are essential, and the PSW is only a summary cover.
2. "Samples with qualified dimensions can be submitted" — CP, MSA, and Cpk must be completed simultaneously.
3. "No need to follow up after provisional approval" — all deviations must be closed within the specified period.
4. "PPAP is over once it's done" — PPAP-approved parts are still subject to change management constraints during mass production.
5. "No need to do PPAP if there are no customer requirements" — internal new projects should also follow PPAP logic for production part verification.

PPAP is not just a stack of forms but a quality checkpoint to verify whether the design can be stably manufactured — crossing this checkpoint gives mass production the confidence it needs.

Knowledge code: 8.3.3

Version: v20260725

Author: Quality Think Tank Quality Think Tank is dedicated to providing systematic professional knowledge, methodologies, and practical tools to quality management practitioners, helping companies continuously improve their quality capabilities.