How to run a process failure mode effects analysis

If your team is tired of discovering defects after they've already reached the customer, a Process Failure Mode and Effects Analysis (PFMEA) is the tool you need. PFMEA is a structured, proactive risk assessment that helps you identify every way a process step can fail, evaluate the impact, and prioritize improvements before problems occur. It's not just for automotive or aerospace—any organization with a repeatable process can use it to reduce errors, cut costs, and build operational excellence.

What is PFMEA and why does it matter?

PFMEA is a methodical approach that looks at each process step to identify risks and possible errors from many different sources—man, method, material, machinery, measurement, and environment (the 6 M's). It focuses specifically on process-related risks, not product design flaws. The goal is to answer critical questions: What could go wrong? Why might it fail? How severe would the impact be? How likely is it to occur? How likely are we to detect it before it causes harm? By systematically evaluating these factors, you can calculate a risk score and implement corrective actions before defects reach customers.

PFMEA is most effective when performed before production begins, when risks are easier and less expensive to fix. However, it's equally valuable as a continuous improvement tool throughout the product lifecycle. In regulated industries such as automotive and medical devices, PFMEA is often expected as part of quality assurance documentation and audit readiness.

The 10-step PFMEA process

Here's a step-by-step guide to running a PFMEA, based on the standard methodology used by quality professionals.

Step 1: Review the process

Start with a process flowchart. Identify each process component and list it in the FMEA table. If the scope feels too big, break the analysis into more manageable chunks. A common mistake is trying to analyze the entire operation at once—focus on one process or sub-process at a time.

Step 2: Brainstorm potential failure modes

Review existing documentation and data to identify all the ways each component can fail. The list should be exhaustive—you can pair down and combine items later. There will likely be several potential failures for each component. For example, in an injection molding process, a failure mode might be a "short shot" (incomplete filling of the mold cavity).

Step 3: List potential effects of each failure

The effect is the impact the failure has on the end product or on subsequent steps in the process. There will likely be more than one effect for each failure. For a short shot, the effect might be a dimensionally incomplete part, leading to customer rejection.

Step 4: Assign Severity rankings

Rate the severity of the consequences of each failure on a scale (typically 1 to 10, with 10 being most severe). This ranking reflects how serious the effect is if the failure occurs.

Step 5: Assign Occurrence rankings

Determine how frequently each failure is likely to occur and rate it on a scale (1 to 10). Use historical data, process knowledge, and any available failure records to inform your rating.

Step 6: Assign Detection rankings

Evaluate the chances that the failure will be detected before it reaches the customer. Rate detection on a scale (1 to 10), where a higher score means the failure is less likely to be caught. If you have no controls in place, detection will be poor (high number).

Step 7: Calculate the Risk Priority Number (RPN)

Multiply Severity × Occurrence × Detection to get the RPN for each failure mode. This number helps you prioritize which risks to address first. The higher the RPN, the greater the risk.

Step 8: Develop an action plan

Decide which failures to work on based on the RPNs. Focus on the highest numbers. Define who will do what by when. Assign owners and deadlines for each corrective action.

Step 9: Take action

Implement the improvements identified by your PFMEA team. This could involve process changes, additional controls, training, or equipment modifications.

Step 10: Calculate the resulting RPN

After improvements are made, re-evaluate each failure mode and recalculate the RPN. This shows the impact of your actions and helps you track risk reduction over time. By comparing before and after RPNs, you create a history of improvement and risk mitigation.

Practical tips for success

• Build a cross-functional team: PFMEA requires input from operators, engineers, quality, and maintenance. A multidisciplinary team ensures you capture different perspectives and avoid blind spots.
• Use a process map: A flowchart is essential for identifying all process steps and their interactions.
• Don't rush the brainstorming: The list of failure modes should be exhaustive. You can always trim later.
• Keep it a living document: PFMEA is not a one-time exercise. Update it whenever processes change, new failure modes are discovered, or real-world data shows your original risk assessment was wrong.
• Link to real data: Without actual failure frequency and detection data from the shop floor, your ratings remain educated guesses. Use production data to validate and refine your rankings.

Quiz: Test your PFMEA knowledge

Before you go, check your understanding with this quick question.

What does the Risk Priority Number (RPN) in a PFMEA represent?

• The product of Severity, Occurrence, and Detection rankings
• The number of failure modes identified in the process
• The total cost of quality failures per year

Correct answer: The product of Severity, Occurrence, and Detection rankings. The RPN is calculated by multiplying these three rankings to prioritize risks.

How the Featured Expert Can Help

If you're ready to put PFMEA into practice but need guidance, Bob Buckwalter at Windy Hill Partners can help. With over 20 years of process improvement experience and documented financial impact exceeding $20 million, Bob has helped organizations across six industries break the cycle of operational chaos. He focuses on equipping your team with the tools to sustain improvement long after the engagement ends. Visit Windy Hill Partners to learn more about how Lean Six Sigma and process improvement consulting can reduce costs, cut errors, and build lasting operational excellence.