What is FMEA

 FMEA is stand for Failure Mode and Effects Analysis. FMEA is a process analysis tool. FMEA is used to identify all the failures or potential failures that may occur in a process, before any physical error occur in the process and analysis consequences due to failures.

It is one of the core tool of IATF16949. Other core tool of IATF16949 are:

1. APQP: Advance Product Quality Planning
2. PPAP: Production Part Approval Planning
3. MSA: Measurement System Analysis
4. SPC : Statistical Process Control

Type of FMEA:

There are two type of FMEA:

1. DFMEA (Design Failure Mode and Effects Analysis)
2. PFMEA (Process Failure Mode and Effects Analysis)

1. DFMEA (Design Failure Mode and Effects Analysis):

DFMEA is a methodology which is used to analyse the risk or failure during new product or process development, it also used during any change or modification in product or process.

2. PFMEA (Process Failure Mode and Effects Analysis)

PFMEA is a methodology which is used to analyse risk or failure during manufacturing process, that effect product quality, customer dissatisfaction, human factors (safety of employees also include in PFMEA) & Method used for production.

FMEA prioritizes failures on basis of severity, frequency and detectability. Where severity describes the seriousness of failure consequences, frequency describes how often failures can occur and detectability describes the degree of difficulty in detecting failures.

FMEA help us to eliminate all risk at deferent levels of the design and manufacturing process of a product. Prioritization of failures helps to minimise severity & occurrence of the problem.

Procedure to perform FMEA:

STEP 1:  Review the process:

Prepare Cross-functional team from different department like, Process, Operations & Sales, then prepare process flow chart to identify the process of manufacturing of the product.

STEP 2:  Brainstorm potential failure modes:

After understanding the process, sit together (team should have Gemba also) to find all possible potential causes for each function that may introduce failure in the process at different stage, that may cause defect in job. In this step we must include documents that are previously created for the same purpose. 

STEP 3:  List potential effects of each failure:

Once all potential causes are found. Now each effect should group with related causes or failure but remember, there may be more than one effect for each failure. 

STEP 4:  Assign Severity rankings:

Now, determine severity of each effect, this can be done thru rating method. Severity is usually rated on a scale from 1 to 10, where 1 is insignificant and 10 is most significant. If a failure mode has more than one effect, write on the FMEA table only the highest severity rating for that failure mode. Severity is denoted by “S”.

STEP 5:  Assign Occurrence rankings:

In this step, we rate failure on the bases of the occurrence. This rating estimates the probability of failure occurring for some reason during the lifetime of the product (From design phase to till the end of the product). Occurrence rated on the scale from 1 to 10, where 1 is Unlike to happen and 10 is unavoidable. Occurrence is denoted by “O”.

STEP 6:  Assign Detection rankings:

In this step, for each cause we have identify current process control, which help us to prevent cause before happening or occurring (something like Poka-yoke). Then we must do detection rating. This rating determine how well control can detect the failure mode or cause before it actually effects the customer. Detection is also done on the scale from 1 to 10, where 1 is denote, control is available and perfect to detect the problem. And 10 means either control is not available or if available is not capable to detect the problem. Detection is denoted by “D”.

STEP 7:  Calculate the RPN:

As we are now able to identify the rating for severity, occurrence and detection for the cause. Now it time to calculate the risk priority number i.e. RPN 

RPN = Severity X Occurrence X Detection.

Also calculate Criticality by multiplying severity by occurrence, S × O

Results should reveal the most problematic areas, and the highest RPNs should get highest priority for corrective measures. 

One point to be take care, that we should also consider failure that include critical characteristics, that should be take care on most priority and in FMEA table this point should have special column.  

STEP 8:  Develop the action plan:

Now, time is to develop action plan based on highest RPN, highest number RPN is to take care first and action is do develop that reduce the severity of cause or reduce the occurrence of cause and create powerful detection method. Action plan should also consider the responsibility of the person/department who will perform the task by target date.

STEP 9:  Take action:

Implement the improvements identified by your Process Failure Mode and Effects Analysis that is done by team in previous step. These ideas are related to give additional control or improvement to the existing failure mode.

STEP 10:  Calculate the resulting RPN:

When corrective measures are implemented, RPN is re-calculated and the results should be documented in the FMEA. 

Till now we are able to understand, what is FMEA, procedure to prepare FMEA and now its time to understand when to prepare FMEA.

There are several times when it is important to perform FMEA (Failure Mode and Effects Analysis):

 

• When we are designing a new product, process, or service

• When an existing process, product, or service is being applied in a new way

• When improvement goals are planned for an existing process, product, or service

• During or after analysing failures of an existing process, product, or service

• We can also perform FMEA periodically.

Re check quality and reliability of the process, product, or service after successfully complete the FMEA.

 

Reverse FMEA (Failure Modes & Effects Analysis) :

RFMEA or Reverse FMEA or Reverse Failure Modes & Effects Analysis is one the recent tool in automotive sector and it helps us to work toward continuous improvement, which is the requirement of the today’s world.

RFMEA is more powerful than normal FMEA.

It is important to know that why Reverse FMEA is more powerful. As FMEA is usually performed in meeting rooms which include experience of members of different departments (usually HODs), but it may some what different from real time situation of shop floor. It is one of the process that help in continuous improvement in the process, as continue to update the process and help us to identify new risks, new failure causes, new failure modes. This method allows us to also enhance the FMEA process by a re-rating of our failures.

Key points performed during RFMEA are:

1. Current process should be review.

2. Actual condition or status of past action plans.

3. Actual data should be collected and analysed.

4. After analyse the data if required update the controls or the process

5. Revision in FMEA to be done.

 

The Reverse FMEA can be carried out as soon as the final process is operational.

 

Reverse FMEA has following benefits :

 

1. RFMEA helps to give better understanding of the process to all the members from different departments, how are the part of the FMEA. 

2. Most important is it help us to improve FMEA.

3. RFMEA help to introduce better controls, that reduce new risks.

4. Improves the documentation and aligned with the actual production plan.

5. Re-rating of the FMEA is done and severity is also changed.