Failure Mode and Effects Analysis(FMEA) for Silicone Molded Products

What is FMEA?

FMEA stands for Failure Mode and Effects Analysis. It is a structured method for asking how a product or process could fail, what the effect would be, why the failure might happen, and what controls should reduce the risk.

For silicone components, FMEA is useful because many important risks are easy to miss during a normal visual check. A tiny flash edge can create leakage. A diaphragm can tear because the wall transition is too sharp. A material mix-up can change hardness or regulatory status. An overmolded seal can look bonded but fail after heat, cleaning, aging, or repeated movement.

FMEA should begin while decisions can still change. It helps the team identify how a part might fail, choose a way to reduce that risk, and define the evidence needed to check the action. The review is updated as the design and process develop.

FMEA helps a team answer four questions:

• What can fail?
• What happens if it fails?
• Why could it fail?
• What should we do to prevent, detect, or reduce the risk?

FMEA can begin during design development and continue into production planning. When a process changes or a failure occurs, the team returns to the analysis to check whether its assumptions and controls still hold.

There are two common forms:

• DFMEA: focuses on how the part design could fail in the final product.
• PFMEA: focuses on how the manufacturing process could create a nonconforming part.

The finished-product manufacturer usually owns the full product risk. The silicone supplier can contribute manufacturing knowledge, PFMEA input, process controls, and part-specific failure modes.

What Buyers Usually Want to Know

People searching for FMEA usually want to understand how to use it, not just what the acronym means. Common questions include:

• What is the difference between DFMEA and PFMEA?
• When should FMEA be created?
• What are severity, occurrence, and detection?
• Is RPN still used?
• What is action priority?
• What should a silicone supplier include in PFMEA?
• How does FMEA connect to control plans, PPAP, FAI, IQ/OQ/PQ, or routine inspection?
• Which silicone failure modes should be considered?

For custom silicone parts, the most useful answer is practical: FMEA should turn likely or severe failure risks into design choices, process controls, inspection plans, and validation evidence.

DFMEA vs PFMEA

DFMEA examines how the component could fail in the finished product and what that failure would mean for the system or the person using it.

Examples include:

• a gasket leaks because compression is too low
• a valve opens at the wrong pressure
• a keypad loses tactile response after repeated use
• a wearable pad irritates skin because material or surface condition is not suitable
• an overmolded seal separates from the plastic insert
• a tube connector cracks, slips, or loses sealing force

PFMEA looks at the manufacturing process. It asks how production could create the failure.

Examples include:

• wrong silicone grade or hardness is used
• mold temperature is too low and the part is under-cured
• cavity variation creates a thin sealing lip
• poor venting causes bubbles or short shot
• trimming damages a diaphragm or valve edge
• post-cure time is incorrect
• packaging introduces particles or deformation
• labels mix two lots or revisions

DFMEA and PFMEA should connect. If the design review identifies leakage as a serious effect, the process review needs to identify how manufacturing could cause that leak. It then defines the controls and checks that protect the sealing function.

Example PFMEA worksheet for a silicone O-ring process review.

When to Use FMEA

FMEA is most valuable before tooling is finalized and before the process is validated or approved.

Use FMEA when:

• a new silicone part is being designed
• a part has sealing, flow control, tactile, bonding, safety, cleanliness, or durability requirements
• a new mold, cavity, fixture, material, or process route is introduced
• a customer asks for risk analysis during PPAP, validation, or supplier approval
• a field issue, complaint, leakage problem, assembly issue, or production defect needs root-cause review
• a design or process change could affect fit, form, function, safety, or regulatory status

For low-risk parts, FMEA can be simple. For automotive, medical, aerospace, or high-reliability components, it should be more formal and connected to the customer quality system.

FMEA Workflow

FMEA can look complicated, but the thinking follows a clear path.

1. Define the part, process step, function, and boundary.
2. List how the function could fail.
3. Describe the effect of each failure.
4. Identify possible causes.
5. Review current prevention and detection controls.
6. Rate the risk using the customer’s required scoring method.
7. Decide whether action is needed.
8. Assign the action, owner, due date, and expected result.
9. Update the FMEA after action is completed.
10. Link the result to the control plan, inspection plan, validation plan, or production approval package.

The most important step is not scoring. The most important step is agreeing what action is needed and proving that the action reduced risk.

Severity, Occurrence, Detection, RPN, and Action Priority

Traditional FMEA often uses three ratings:

• Severity: how serious the effect is if the failure reaches the user or next process.
• Occurrence: how likely the cause is to happen.
• Detection: how likely current controls are to detect the failure before release.

Older FMEA systems often multiplied these scores into an RPN, or Risk Priority Number. Many teams still use RPN, but it has limits. A low occurrence score can hide a severe safety or sealing risk, and two very different risks can produce the same RPN.

Automotive programs using AIAG-VDA style FMEA often focus on Action Priority. This approach gives more weight to the meaning of the severity, occurrence, and detection combination instead of relying only on one multiplied number.

A score should not replace engineering judgment. A failure with serious consequences deserves careful review even when it appears unlikely. Consider what happens in the finished assembly and who could be affected, then decide whether the proposed controls are sufficient.

How FMEA Connects to Validation and Production

FMEA should not sit alone. It should influence the documents and checks that control the part later.

Features identified as critical in FMEA should appear in the FAI report. For PPAP, the process risks should lead to controls supported by measurement and production evidence. In IQ/OQ/PQ planning, those same risks help determine which operating limits to challenge and which sources of variation to include.

Carry those controls into routine work instructions and inspection plans. Train operators to recognize the relevant failures, and review changes against the risks already identified.

If FMEA says a feature is important but the production process does not control it, the risk review is incomplete.

Silicone Manufacturing Controls to Consider

For silicone rubber manufacturing, avoid generic wording such as “process variation” when a more useful control can be named.

Important controls may include:

• Material controls: silicone grade, hardness, colorant, lot number, certificate, shelf life, storage condition, and change control.
• Tooling controls: cavity revision, venting, parting line, flash allowance, surface finish, gate location, and cavity identification.
• Molding controls: injection pressure, injection speed, mold temperature, cure time, shot size, press pressure, vacuum, and demolding method.
• Post-cure controls: oven qualification, temperature profile, load spacing, time, airflow, and lot separation.
• Secondary operation controls: trimming, punching, printing, coating, bonding, plasma treatment, adhesive or primer handling, and fixture repeatability.
• Cleanliness controls: cleanroom class, operator garments, handling method, bagging, washing if used, drying, and packaging condition.
• Inspection controls: gauge repeatability, visual criteria, limit samples, leak testing, force testing, dimensional inspection, and functional testing.
• Traceability controls: material lot, machine, mold, cavity, operator, process recipe, inspection record, and release record.

These controls should be specific enough that production staff can actually follow them and quality staff can verify them.

Where FMEA Matters

FMEA fits the General category because the method can be used in almost any silicone program. The level of formality changes by industry.

Automotive programs place strong emphasis on FMEA because its findings feed into production planning and PPAP. The risks identified during development should remain visible in the control plan after launch.

In medical projects, FMEA can examine component and process failures that may contribute to patient or user harm. It supports the broader risk-management work but does not replace it. The device team must connect those findings with the required validation and biological evaluation.

Aerospace teams use FMEA to examine the consequences of functional failures. Findings help define controls for critical features and the supplier evidence needed to support them.

Other industries may use a simpler format, but the purpose remains the same. If failure of a silicone part could compromise the finished product, FMEA helps the team decide how to prevent or detect it.

Conclusion

FMEA helps silicone teams turn risk into action. It identifies how a silicone part or manufacturing process could fail, what the effect could be, why it may happen, and which controls should prevent or detect the issue.

A useful FMEA changes decisions. The team should be able to point to a design improvement or production control that follows from an identified risk, then show how its effectiveness was checked. Completing the scoring sheet is only part of that work.