Production Part Approval Process(PPAP) for Automotive Silicone Components

PPAP stands for Production Part Approval Process. In automotive manufacturing, it is the formal way a supplier shows that it understands the customer’s engineering requirements and can make production parts that meet those requirements under normal manufacturing conditions.

For a buyer, PPAP addresses a practical question: can this supplier repeatedly make conforming parts at the intended production rate? The evidence must represent the process that will actually be used.

A small manufacturing change can affect a silicone part after assembly. Flash may interrupt a seal, while a hardness shift can change compression. PPAP helps check that the process controls those details and that the inspection method can assess them reliably.

PPAP is most closely tied to the automotive industry. Other industries may borrow some PPAP-style documents, but a formal PPAP request normally comes from automotive OEMs, tier suppliers, or customers following automotive quality requirements.

Quick Answer

PPAP brings the production approval evidence into one package for the customer to review. It links the design requirements to the proposed process and its measured results. Submitted samples and the signed Part Submission Warrant complete the submission as required by the customer.

The purpose is not to prove that one sample is good. The purpose is to show that the supplier’s production process is ready to make conforming parts consistently.

Most people searching “what is PPAP” are trying to answer five practical questions:

What does PPAP mean?
When does a customer require it?
What documents are included?
What is the difference between PPAP levels 1, 2, 3, 4, and 5?
How is PPAP different from FAI, APQP, FMEA, or routine inspection?

This article answers those questions from the point of view of custom silicone rubber parts.

Why PPAP Exists

Prototype samples can hide risk. A supplier may be able to make a few acceptable parts by adjusting the process by hand, selecting the best pieces, or using temporary materials. That does not prove the real production process is ready.

PPAP closes that gap. It asks the supplier to connect the finished part to the full production system:

released drawing and revision
approved material
production tooling
production-rate run
process flow
PFMEA and control plan
measurement system
dimensional results
material and performance test results
customer-specific requirements
signed submission warrant

For silicone parts, this production-system view is important. The same drawing may produce different results if the mold temperature changes, the LSR mix ratio drifts, the compression mold flash line is moved, the post-cure cycle changes, or the measurement method deforms a soft part during inspection.

When PPAP Is Required

A customer may request PPAP for a new part, a new production process, or a meaningful change to an existing approved part. In automotive programs, the requirement is usually defined by the customer, purchase order, supplier quality manual, or customer-specific requirements.

Common PPAP triggers include:

new automotive part number
new drawing revision
new mold, cavity insert, extrusion die, fixture, or checking aid
change in manufacturing location
change in production equipment or process route
change in silicone grade, hardness, color, curing system, primer, coating, or adhesive
correction of a previous nonconforming submission
production restart after extended inactivity, when required by the customer
customer request after a field issue, quality concern, or supplier change

For silicone rubber components, even small changes can matter. A change from one LSR grade to another may affect compression set, tear resistance, bonding, transparency, extractables, or long-term aging. A minor mold repair may shift flash location on a sealing surface. A new trimming fixture may improve appearance but damage a thin lip. These are the types of risks PPAP tries to make visible before mass production.

PPAP vs FAI vs APQP

PPAP is often confused with FAI and APQP. They are connected, but they are not the same.

Term	Main purpose	Typical question
FAI	Check first article samples against the drawing and specification	Do these inspected samples match the requirement?
APQP	Plan product quality before and during development	Have the product and process risks been planned and controlled?
FMEA	Identify and reduce design or process risk	What could fail, how serious is it, and what controls are needed?
PPAP	Submit evidence that production parts and the production process are ready	Can this supplier repeatedly make conforming parts under approved production conditions?

FAI mainly reports whether the first article samples meet their specified requirements. PPAP also examines the production system behind those parts, using risk analysis and process controls supported by measurement and capability evidence. Its scope includes the samples and records required by the customer.

APQP happens before PPAP and feeds into it. A good PPAP package is often the evidence that APQP work has been completed well enough for customer approval.

The 18 PPAP Elements

The AIAG PPAP framework is commonly described through 18 elements. The exact submission depends on the customer and PPAP level, but the logic behind the elements is easier to understand if they are grouped by what the customer is trying to confirm.

Customer question	PPAP elements that support it	What it means for silicone parts
Is the product definition controlled?	Design records, engineering change documents, customer engineering approval	The silicone part must match the released drawing, material callout, revision, color, hardness, and any approved engineering changes.
Have design and process risks been reviewed?	DFMEA, process flow diagram, PFMEA, control plan	Risks such as flash, short shot, bonding failure, hardness drift, contamination, tearing, or leakage should be reflected in the process controls.
Can the supplier measure the part correctly?	MSA, checking aids, dimensional results	Soft silicone parts need measurement methods that do not distort thin walls, lips, gaskets, tubes, or keypads.
Do the material and performance results meet requirements?	Material test results, performance test results, qualified laboratory documentation	Test evidence may include hardness, tensile strength, elongation, tear strength, compression set, aging, bonding, leakage, or functional force.
Do real production samples support approval?	Initial process studies, sample production parts, master sample, appearance approval if required	Samples should come from production tooling and intended process conditions, not from a hand-tuned trial that cannot be repeated.
Are customer-specific items closed?	Customer-specific requirements, Part Submission Warrant	The PSW summarizes the submission and records the supplier’s declaration for customer review and disposition.

The 18 elements are not meant to be a paperwork exercise. They are a way to show that engineering requirements, manufacturing reality, and inspection control are aligned.

PPAP Submission Levels

PPAP has five common submission levels. The level does not simply mean “easy” or “hard.” It defines what the supplier submits to the customer and what may be retained at the supplier’s site for review.

Level	Common meaning
Level 1	Part Submission Warrant only.
Level 2	PSW with product samples and limited supporting data.
Level 3	PSW with product samples and complete supporting data. This is often the default for new part approval unless the customer specifies otherwise.
Level 4	PSW plus other requirements defined by the customer.
Level 5	PSW with product samples and complete supporting data available for review at the supplier’s manufacturing location.

The customer decides the level. A low-risk bracket seal from a proven supplier may not need the same submission burden as a safety-related battery-pack seal, connector gasket, or thermal interface component. The safest approach is to confirm the level and customer-specific requirements before tooling release, not after samples are already molded.

What PPAP Looks Like for Silicone Rubber Parts

A PPAP package for silicone parts should be built around how the part is actually made and how it fails in use. A generic document list is not enough.

For LSR parts, show how the material and A/B ratio are controlled within the approved molding window. Results should be traceable to the relevant cavities. Document the acceptance limits for dimensions and flash, along with any specified post-cure and packaging steps.

For compression molding, the package should show how the preform is prepared and loaded, then how the cure cycle is controlled. Inspection needs to confirm consistent hardness and appearance after any trimming or post-curing.

For overmolded parts, document the substrate and how its surface is prepared for bonding. The customer will need evidence that the chosen process produces an acceptable bond. Record the agreed pull or peel test and describe where the sample fails.

For automotive seals, connect dimensional results to how the part compresses and resists leakage in the assembly. Aging and fluid-exposure tests check whether it retains that function. For keypads, evaluate the force and return behavior together with reliable electrical contact.

PPAP Workflow

A practical PPAP workflow should start before the first production run.

Confirm the customer’s PPAP level and customer-specific requirements.
Review the drawing, revision, material callout, special characteristics, and test requirements.
Build the process flow from incoming material through molding, curing, trimming, washing, inspection, packaging, and shipping.
Prepare PFMEA and control plan around real silicone process risks.
Confirm measurement methods and any MSA or gauge study required for critical features.
Produce parts under intended production conditions, using approved tooling, material, equipment, and operators.
Inspect dimensional, material, visual, functional, and packaging requirements.
Prepare sample parts, master sample, checking aid records, and supporting documents.
Complete the PSW and submit the PPAP package according to the requested level.
Wait for customer disposition before treating the part as fully approved for production shipment.

If the customer rejects the submission or grants only interim approval, the supplier should treat that result as a controlled action item. The issue may require corrective action, updated data, new samples, or a revised submission.

What Buyers Actually Want

Most buyers do not ask for PPAP because they enjoy paperwork. They want confidence before approving production.

For automotive silicone parts, PPAP should help the buyer see:

the supplier understands the drawing and revision
the chosen silicone material matches the application
the tooling and process can make repeatable parts
critical dimensions and functions are controlled
inspection methods are suitable for soft elastomer parts
risks have been reviewed before mass production
the submitted samples represent the intended process
changes will not be made silently after approval

A well-prepared PPAP helps identify production weaknesses before launch. It gives the customer evidence that the part fits and functions as specified, and that the proposed process can repeat that result.

Conclusion

PPAP is the automotive customer’s approval process for production parts and production processes. It is broader than FAI because it is not limited to first article inspection results. It is also not a replacement for APQP or FMEA; it uses their outputs as part of the evidence package.

Build the PPAP around how the silicone part works in its assembly. Identify the manufacturing conditions that control that function and provide evidence that they remain consistent. The package should demonstrate conformity under the customer’s approved conditions, rather than simply accumulate documents.