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Steps in performing an FMEA analysis

A FMEA is a risk and potential failure identification methodology which is used as a tool to identify and quantify both the probability and effect of a failure or potential problem eventuating. FMEA stands for Failure Mode and Effect Analysis. A FMEA is used in many different applications, the most common being in a manufacturing, process or assembly application where the analysis will try and quantify the different failure modes of product, part or machine and the effects of these happening. This analysis tool can also be used in a diverse range of applications from building and infrastructure projects to interactive customer service systems or technology.

A FMEA analysis is usually performed in a team environment with the appropriate stakeholders in the plant or process such as a selection of operators, team leaders, engineers and managers which understand the product, factory, process and technology used.

Understanding of the materials, inputs as well as the different stages in a process is crucial in identifying all or as many potential failures that could eventuate and provide losses to customers, the producer or the general public.

In some large organizations a lean/kaizen team will guide the FMEA process and using a standard FMEA form or template. Although the process may seem standardized it is encouraged to think and brainstorm outside the box to be able to comprehensively analyze and quantify all the potential failures and risks.

The FMEA process steps

The FMEA process will usually follow a process similar to the steps outlined below.
-Step 1: List the steps or tasks in the process or list the parts and components of the plant

-Step 2: List the potential failure modes for each step, task or plant component

-Step 3: List the effects of each failure on the process, business, and or plant

-Step 4:Calculate a Risk priority rating for each failure mode this is equal to the product of probability of occurrence, severity of consequence and probability of detecting the failure.

-Step 5: Then each failure mode is discussed and preventive actions are specified including who will put these measures into place

-Step 6: The preventive actions are then organized by their respective failure mode risk priority rating, and then this will represent the order in which they should be implemented

Once the list of preventive actions has been finalized including the priority with which these items will be completed, the maintenance and operations team need to ensure these items are completed as soon as possible.

FMEA Risk Priority Number

As part of the FMEA process a Risk Priority Number or RPN is calculated for each potential failure mode or potential risk. This is later used to rank the potential failures and risks from highest impact risks to the lowest. Usually the Highest RPN failure modes will be addressed first in the action list of improvements, solutions or risk mitigation measures to be implemented.

Formula to Calculate the Risk Priority Number

RPN= Severity (Effects of failure) x Occurrence (Probability of happening) x Detection (Ability to Identify the issue)

Example of RPN calculation:
Manufactured part: Suspension assembly in sedan car
Possible failure: Spring bracket failing (breaking)
Potential Effects: Spring loose, extreme vibration, damage to suspension supports and system

Severity: (7/10) , Can cause severe damage to suspension system and vehicle not safe to drive
Occurrence: (2/10), Unlikely to occur
Detection: (8/10), Difficult to detect as not covered in service checks and in difficult position to see

RPN= 7 X 2 X 10 = 140

This Failure would then be ranked against the other failures or risks and their RPN's so that the highest risks may be addressed first.

In this example RPN of around 140 would be considered a medium to high risk item which should be addressed or measures put in place to avoid it happening

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