Introduction to FMEA

To mitigate risks, the US Military developed a system in the 1940s to analyse potential failures and their consequences caused by reliability engineering departments. Following military use, this approach, which came to be called FMEA, became an essential process-failure-rectifying tool across organisations—from NASA to Ford. 

When handling bigger projects, it is essential to prevent critical quality-related risks, which can be analysed beforehand. This is where FMEA, or Failure Mode and Effects Analysis, comes into play. 

What is FMEA?

FMEA is a structured, systematic technique used to identify and prevent potential failures in products, processes, or services before they occur. It is a proactive risk analysis tool that helps organisations anticipate and mitigate risks associated with their operations.

There are two parts to FMEA.
Identification of Failure Modes: This involves systematically identifying potential failure modes within the system, product, or process being analysed. In a failure mode, the system, product, or process could fail to meet its intended function or performance requirements.

Assessment of Risk: Once failure modes are identified, the next step is to assess the associated risks. This assessment involves evaluating the severity of each failure mode (the potential impact on the system or end-user), the likelihood of occurrence, and the detectability of the failure before it affects the end-user. 

These three factors help determine the Risk Priority Number (RPN) for each failure mode, prioritising which requires the most immediate attention and mitigation efforts.

Role of Risk Priority Number in FMEA

In the Failure Mode and Effects Analysis (FMEA) process, the Risk Priority Number (RPN) prioritises and determines the most critical areas that require immediate attention and corrective actions.

Calculation of RPN

The RPN is calculated by multiplying three factors: Severity (S), Occurrence (O), and Detection (D). The formula for calculating RPN is:

RPN = Severity (S) × Occurrence (O) × Detection (D)

Severity (S): It represents the seriousness of the potential effect or consequence of the failure mode. Severity is typically rated on a scale of 1 to 10, with 10 being the most severe.

Occurrence (O): This is the likelihood or frequency of the cause or failure mode occurring. Occurrence is also typically rated on a scale of 1 to 10, with 10 being the highest likelihood of occurrence.

Detection (D): This is about the potential of detecting the cause or failure mode before it reaches the customer or end-user. Detection is rated on a scale of 1 to 10, with 10 being the lowest likelihood of detection.

The RPN can range from 1 (1 × 1 × 1) to 1000 (10 × 10 × 10), with higher values indicating higher risks associated with the failure mode.

Types of FMEA

There are three types of FMEA, which varies across industries. 

Design FMEA (DFMEA)

This helps identify and evaluate potential failure modes in the early stages of product development. It aims to anticipate and address issues arising from design flaws or shortcomings. 

Typically, cross-functional teams are involved, and they analyse the product's components, subsystems, and interfaces to determine how each element could fail, the potential effects of these failures, and the likelihood of occurrence. You will find this process in automotive and aerospace industries. 

Engineers and designers can implement design changes or improvements to enhance product reliability, safety, and performance by identifying and prioritising these failure modes.

Process FMEA (PFMEA)

PFMEA focuses on assessing risks associated with manufacturing or assembly processes. It involves analysing each step of the production process to identify potential failure modes, such as equipment malfunctions, material defects, human errors, or environmental factors. 

Similar to DFMEA, PFMEA aims to evaluate the severity, occurrence, and detectability of these failure modes to prioritise mitigation efforts. 

By implementing preventive measures or process improvements based on PFMEA findings, manufacturers can minimise the likelihood of defects, improve product quality, and enhance overall efficiency in production operations. Food manufacturers go for this method mostly. 

System FMEA (SFMEA)

SFMEA extends its principles to evaluate risks at the system level, considering the interactions and dependencies among various components, subsystems, and interfaces within a larger system or product. 

It aims to identify potential failure modes that could impact the system's overall functionality, reliability, and safety. The healthcare industry has this. 

SFMEA involves analysing system architecture, integration points, and operational scenarios to assess the consequences of failures and develop strategies to mitigate risks.

By conducting SFMEA, engineers and stakeholders can gain insights into potential vulnerabilities and proactively address them to ensure the robustness and resilience of the system as a whole.

The 8-Step FMEA Process

Here is how you should go about the FMEA process. 

1. Identify potential failure modes: List all possible ways a component, system, or process could fail to meet its intended function.
2. Determine the potential effects of each failure mode: Analyse the consequences of each failure mode on the product, process, or system.
3. Assign severity ratings: Rate the severity of each potential effect, considering factors such as safety, compliance, and customer impact.
4. Identify potential causes: Determine the root causes that could lead to each failure mode.
5. Assign occurrence ratings: Estimate the likelihood of each cause occurring.
6. Assign detection ratings: Evaluate the ability to detect each failure mode or cause before it manifests.
7. Calculate risk priority numbers (RPN): Multiply the severity, occurrence, and detection ratings to obtain an RPN for each failure mode.
8. Prioritise and take actions: Prioritise failure modes based on their RPN values and implement corrective or preventive actions to address high-risk areas.

How FMEA is Implemented in Six Sigma Projects

Focusing on reducing the occurrence of failures is crucial because it directly improves customer satisfaction and process reliability. These aspects align with the Six Sigma methodology's emphasis on continuous improvement based on customer needs.

FMEA finds its application predominantly during the Analyse phase of the DMAIC (Define, Measure, Analyse, Improve, Control) cycle. 

It helps identify vulnerable areas within processes, enabling teams to delve deeper into product features and process tasks susceptible to defects and failures.

Check out Six Sigma courses to equip yourself with the necessary skills to implement FMEA effectively and drive organisational excellence. And if confused where to start, you can have a look at the Six Sigma career path.