PFMEA | Process FMEA | Process Failure Mode and Effects Analysis
What is PFMEA or Process FMEA?
→ PFMEA is a Process Failure Mode Effects Analysis.→ It is a structured analytical tool used by an organization, business unit or cross-functional team to identify and evaluate the potential failures of a process.
→ Process Failure Mode Effects Analysis helps us to establish the impact of the failure.
→ PFMEA (Potential Failure Mode Effects Analysis) also provides a framework for identifying & prioritize the action for the items having a risk factor for minimizing the risk.
→ It is a live document that should be updated through the process of production and maintained it through the life cycle of the product.
➤ PFMEA or Process FMEA Report:
→ The format of the PFMEA
(Process Failure Mode and Effects Analysis)
Report is mentioned below:
👉
Download: PFMEA Excel Template and Severity Occurrence & Detection
Table
10 Easy Steps for making PFMEA:
→ There are 10 Simple steps for making Process Failure Mode and Effects Analysis Report is mentioned below:
- Review the process & It's Requirement
- Brainstorm potential failure modes
- List the potential effects of failure
- Assign Severity rankings
- Assign Occurrence rankings
- Assign Detection rankings
- Calculate the RPN
- Develop an action plan
- Take Action
- Calculate the resulting RPN
➤ 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 Problem-finding and Problem-solving methodologies.
→ There are many Problem-finding and Problem-solving methodologies.
➥ The occurrence ranking scale:
→ Likes 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 critical 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 Project 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.
→ This step in a Process Failure Mode and Effects
Analysis confirms the action plan had the desired results by
calculating the resulting RPN.
→ To recalculate the
RPN, and reassess the severity, occurrence, and detection
ranking for the failure modes after the action plan has been
completed.
Benefits of Process FMEA:
→ Process FMEA identifies potential failure modes during a new product or process setup.→ PFMEA assesses the potential customer effects of the failures.
→ The Process FMEA identifies potential manufacturing and/or assembly process causes.
→ It identifies significant process variables to focus controls for the occurrence reduction and detection of failure conditions.
→ Process FMEA develops a list of potential failure modes ranked according to their effect on the customer.
→ We can set a priority for corrective and preventive action for the potential failure modes with the help of PFMEA.
informative, good job.
ردحذفThanks and happy learning!!!
حذفReal good
ردحذفThanks and happy learning
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