➤ Process FMEA Step 1 | Review the process & It's Requirement



→ Use a process flowchart to identify each process component in Process Failure Mode and Effects Analysis.

→ List each process component in the FMEA table.





➥ Review the process components and the intended function

→ Use of a detailed flowchart of the process

→ The detailed flowchart is a good starting point for reviewing the process. → With the process flowchart in hand, the PFMEA (Process Failure Mode and Effects Analysis) team members should familiarize themselves with the process by physically walking through the process. → This is the time to assure everyone on the team understands the basic process flow and the workings of the process components.





➥ There are several reasons for reviewing the process

→ The first reason is reviewing the process helps us to assure that all team members are familiar with the process.

→ A second reason for reviewing the process is to identify each of the main components of the process.

→ The third reason for reviewing the process is to assure that you are studying all components of the process with the Process FMEA.





➤ Process FMEA Step 2 | Brainstorm potential failure modes

→ Review existing documentation and data for hints about all the possible ways that the component can fail.

→ Consider the potential failure modes for each component and its corresponding function in this step of PFMEA .

→ A potential failure mode represents any manner in which the component or process step could fail to perform its intended function or functions.

→ Using the list of components and related functions generated in Step 1, as a team, brainstorm the potential failure modes for each function.

→ Don’t take shortcuts here; this is the time to be thorough.

→ Prepare for the brainstorming session.

→ Before you finish the brainstorming session, review the documentation for possible causes of potential failure modes.





➤ Process FMEA Step 3 | List potential effects of failure

→ There may be more than one effect of failure for each failure in the 3rd step of PFMEA.





➥ Determine the effects related to each failure mode.

→ Some failures will have an effect on the customers and others on the environment, the facility, and even the process itself.

→ The effect should be stated in meaningful terms.

→ If the effects are defined in general terms, it will be difficult to identify (and reduce) true potential risks.





➤ Process FMEA Step 4 | Assign Severity rankings

→ Severity rankings are based on the severity of the consequences of failure in the 4th step of PFMEA ( Process Failure Mode and Effects Analysis) .





➥ Assign a severity ranking to each effect that has been identified.

→ The severity ranking is an estimate of how serious an effect would be should it occur.

→ To determine the severity, consider the impact the effect would have on the customer, on downstream operations, or on the employees operating the process.





➥The severity ranking is based on a relative scale ranging from 1 to 10.

→ A “10” means the effect has a dangerously high severity leading to a hazard without warning.

→ Conversely, a severity ranking of “1” means the severity is extremely low.





➤ Process FMEA Step 5 | Assign Occurrence rankings

→ Occurrence rankings are based on how frequently the cause of the failure is likely to occur in the 5th step of PFMEA.

→ Next, consider the potential cause or failure mechanism for each failure mode; then assign an occurrence ranking to each of those causes or failure mechanisms.

➦ If we know the cause, we can better identify how frequently a specific mode of failure will occur. How do you find the root cause?

→ One of the easiest to use is the 5-Whys technique.

→ Once the cause is known, capture data on the frequency of causes.

→ Sources of data may be scrap and rework reports, customer complaints, and equipment maintenance records.

→ There are many There are many Problem-finding and Problem-solving methodologies.





➥ The occurrence ranking scale: → L ikes severity ranking, It is on a relative scale from 1 to 10.

→ An occurrence ranking of “10” means the failure mode occurrence is very high and happens all of the time.

→ “1” means the probability of occurrence is very low.





➤ Process FMEA Step 6 | Assign Detection rankings

→ Based on the chances the failure will be detected prior to the customer finding it in the 6th step of Process Failure Mode and Effects Analysis.





➥ The Detection ranking scale:

→ A Detection ranking of “1” means the chance of detecting a failure is certain. → Conversely, a “10” means there is absolute certainty of non-detection. → This basically means that there are no controls in place to prevent or detect.





➤ Process FMEA Step 7 | Calculate the RPN

➥ Calculation of RPN (Risk Priority Number) → RPN = Severity X Occurrence X Detection.

→ The RPN is the Risk Priority Number. → The RPN gives us a relative risk ranking. → The higher the RPN, the higher the potential risk. → The RPN is calculated by multiplying the three rankings together. → Multiply the Severity ranking times, Occurrence ranking times and Detection ranking. → Calculate the RPN for each failure mode and effect.



⟹ Note: → The RPN gives us an excellent tool to prioritize focused improvement efforts.





➤ Process FMEA Step 8 | Develop an action plan



→ Define who will do what by when in the 8th step of PFMEA.





➥ Action Plan Development for High RPN value

→ The RPN can be reduced by lowering any of the three rankings (severity, occurrence, or detection) individually or in combination with one another. → A reduction in the Severity ranking for a Process Failure Mode and Effects Analysis is often the most difficult. → The severity usually requires a physical modification to the process equipment or layout. → Reduction in the Occurrence ranking is accomplished by removing or controlling the potential causes.

→ Mistake-proofing tools are often used to reduce the frequency of occurrence.

→ A reduction in the Detection ranking can be accomplished by improving the process controls in place.

→ Adding process fail-safe shut-downs, alarm signals (sensors or SPC), and validation practices including work instructions, set-up procedures, calibration programs, and preventative maintenance is all detection ranking improvement approaches.





➥ What is considered an acceptable RPN? → The answer to that question depends on the organization.

→ For example, an organization may decide any RPN above a maximum target of 160 presents an unacceptable risk and must be reduced. → If so, then an action plan identifying who will do what by when is needed. → There are many tools to aid the PFMEA (Potential Failure Mode Effects Analysis) team in reducing the relative risk of failure modes requiring action.





➥ Powerful tools for reducing RPN number:

→ Mistake-Proofing (Poka Yoke) - "A Techniques that can make it impossible for a mistake to occur, reducing the Occurrence ranking to 1. Especially important when the Severity ranking is 10.

→ Statistical Process Control (SPC) - " A statistical tool that helps define the output of a process to determine the capability of the process against the specification and then to maintain control of the process in the future."

→ Design of Experiments (DOE) - " A family of powerful statistical improvement techniques that can identify the most c ritical variables in a process and the optimal settings for these variables."





➤ Process FMEA Step 9 | Take action



➥ Implement the improvements identified by your PFMEA team in the 9th step:

→ The Action Plan outlines what steps are needed to implement the solution, who will do them, and when they will be completed.

→ A simple solution will only need a Simple Action Plan → While a complex solution needs more thorough planning and documentation. → Sometimes P roject management tools such as PERT Charts and Gantt Charts will be needed to keep the Action Plan on track.

→ Responsibilities and target completion dates for specific actions to be taken are identified.



➤ Process FMEA Step 10 | Calculate the resulting RPN

➦ Re-evaluate each of the potential failures once improvements have been made and determine the impact of the improvements.