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PPAP Production Part Approval Process — Key Points You Need to Know
In the sealing industry, PPAP (Production Part Approval Process) is more than a quality formality.
This is especially true for oil seals and O‑rings. It ensures your rubber seals meet exact specs for material, size, hardness, and performance.
This helps prevent leaks, assembly failures, and costly downtime.
It supports hydraulic, pneumatic, automotive, and mechanical equipment.
What Is PPAP, and Why It Matters for Oil Seals & O‑Rings
- The supplier fully understands your drawing requirements, specifications, and testing standards.
- The production process can consistently manufacture acceptable oil seals and O‑rings under actual mass‑production conditions.
- Material (NBR, FKM, EPDM, HNBR, silicone, etc.) must be correct.
- Hardness, tensile strength, compression set, and heat resistance must match requirements.
- Dimensions, tolerances, and surface quality must be repeatable.
Production Part Approval Process (PPAP) History
The Production Part Approval Process (PPAP) was originally developed by the Automotive Industry Action Group (AIAG). It improves trust in suppliers and their production processes in the automotive supply chain.
“All customer engineering design record and specification requirements are understood by the supplier. The process can consistently produce a product that meets these requirements. This applies during an actual production run at the quoted production rate.”
When Is PPAP Required for Oil Seals & O‑Rings?
- New part number: First-time production of an oil seal or O‑ring.
- Design change: Changes in drawing dimensions, material, lip structure, or mold.
- Process change: New mold, new production line, new factory, or new rubber compound.
- Quality correction: Re‑approval after defects, out‑of‑spec dimensions, or material nonconformity.
- Customer request: Required by automotive, hydraulic, or industrial OEM buyers.
Core PPAP Documents for Oil Seals & O‑Rings
1.Part Submission Warrant (PSW)
- Part name, number, and revision
- Material specification
- Approval level
- Whether all results meet requirements
2.Design Records & Drawings
- Inner diameter (ID), outer diameter (OD), width
- Tolerances
- Material and hardness
- Lip design (for oil seals)
- Marking requirements
3.Dimensional Inspection Results
- All critical dimensions checked
- Min/max values recorded
- Go/no-go results clearly marked
- One sample kept as the standard master sample
4. Material & Performance Test Reports
- Material certificate (actual batch)
- Hardness (Shore A)
- Tensile strength & elongation
- Compression set
- Heat resistance, oil resistance (if required)
5.Process Flow Diagram & Control Plan
- Mixing → molding → deflashing → inspection → packaging
- Key control items for dimensions, appearance, and material
6.Initial Process Study (CpK / PpK)
- Typically requires CpK ≥ 1.33 for critical dimensions
- Ensures mass production will stay within tolerance
7.Sample Products & Master Sample
- Represent actual mass production
- Used as visual reference for future batches
Note: The 18 elements may differ slightly between the automotive and aerospace industries.
Here is a handy chart that shows the 18 elements by level.
| # | Requirement | Level 1 | Level 2 | Level 3 | Level 4 | Level 5 |
|---|---|---|---|---|---|---|
| 1 | Design Records of Saleable Product | R | S | S | * | R |
| 1.1 | for proprietary components / details | R | R | R | * | R |
| 1.2 | for all other components / details | R | S | S | * | R |
| 2 | Engineering Change Documents, if any | R | S | S | * | R |
| 3 | Customer Engineering Approval, if required | R | R | S | * | R |
| 4 | Design FMEA | R | R | S | * | R |
| 5 | Process Flow Diagrams | R | R | S | * | R |
| 6 | Process FMEA | R | R | S | * | R |
| 7 | Control Plan | R | R | S | * | R |
| 8 | Measurement System Analysis Studies | R | R | S | * | R |
| 9 | Dimensional Results | R | S | S | * | R |
| 10 | Material, Performance Test Results | R | S | S | * | R |
| 11 | Initial Process Studies | R | R | S | * | R |
| 12 | Qualified Laboratory Documentation | R | S | S | * | R |
| 13 | Appearance Approval Report (AAR), if applicable | S | S | S | * | R |
| 14 | Sample Product | R | S | S | * | R |
| 15 | Master Sample | R | R | R | * | R |
| 16 | Checking Aids | R | R | R | * | R |
| 17 | Records of Compliance with Customer-Specific Requirements | R | R | S | * | R |
| 18 | Part Submission Warrant (PSW) | S | S | S | S | R |
| 19 | Bulk Material Requirements Checklist (for bulk material PPAP only) | S | S | S | S | R |
S = The supplier must give the customer the relevant records or documents. The supplier must keep copies in appropriate locations.
R = The organization shall keep the required documentation at appropriate locations and provide it to the customer upon request.
* = The supplier shall maintain the documentation at appropriate locations and submit it to the customer when requested.
The rigorous PPAP process and documented evidence ensure that components produced by suppliers consistently meet customer quality and performance requirements.
This gives manufacturers confidence in the accuracy and repeatability of parts used in their production. Furthermore, PPAP helps reduce the risk of downstream defects and costly product recalls, while accelerating time-to-market.
The use of PPAP delivers clear benefits to both suppliers and customers.
PPAP Approval Levels for Sealing Products
Suppliers typically submit at Level 3 (most common):
PSW
Dimension results
Material test reports
Control plan
Samples
Levels 1, 2, 4, 5 are used only when specified by the customer.
PPAP Approval Results
1.Full Approval
Production and shipment may begin.
2.Interim Approval
Temporary approval for a small quantity; must correct issues within a deadline.
3.Rejected
Must revise dimensions, material, or process and resubmit.
Common PPAP Issues for Oil Seals & O‑Rings
- Wrong material: NBR used instead of FKM, or incorrect hardness.
- Dimension out of tolerance: ID, OD, or lip size not matching drawing.
- Incomplete test reports: Missing compression set or oil resistance data.
- Unstable process: Low CpK due to poor mold or process control.
- Non‑standard labeling or packaging: Not meeting customer requirements.
Summary for Customers: Why PPAP Protects You
- Correct material and performance
- Stable dimensions and tolerances
- Repeatable quality in mass production
- Full traceability for every batch
- Lower risk of leakage, failure, and downtime
- Communicate clearly with your sealing supplier
- Review documents efficiently
- Avoid quality risks
- Ensure stable supply for your equipment and assembly lines
For more information, please call +8618730921709 or fill out an inquiry form to request a quote.
