Six Sigma eliminates product defects, errors and failures that detract from the customer’s experience. Failure Modes and Effects Analysis (FMEA) gives Six Sigma project teams a tool to help them predict the most likely process failures that will impact a customer. FMEA also helps estimate the significance of the impact.
FMEA is employed during the Analyze phase of the Six Sigma DMAIC cycle. It can help project teams identify product features and process tasks that are more prone to defects and failure. Armed with the insights that FMEA provides, project teams can enhance product quality and reduce errors by modifying existing processes or creating a new process to correct potential defects.
Putting FMEA into Practice
Project teams with a detailed functional knowledge of the process benefit the most from FMEA. When this detailed functional knowledge is strictly bounded by a well-defined project scope, the results are even better.
Project teams typically apply FMEA in a series of steps:
- Compile a list of failures that could happen in each step of the process.
- Measure the impact of every failure by asking: What happens when this failure occurs?
- Determine how serious the failure is by rating it on a ten-point scale. A 1 is a defect the customer doesn’t even notice; a 10 is a catastrophe. This measures severity.
- Use the 10-point scale to measure the likelihood of failure. 1 indicates no chance; 10 guaranteed failure. This measures occurrence.
- Establish the probability of discovering the error before the customer does. If a failure is easy to discover it gets a 1. Undetectable failures are assigned a 10. This measures detection.
Making FMEA Work for You
Once the project team has ranked the probabilities of failure, it is ready to calculate the Risk Priority Number (RPN). The RPN results from multiplying the three rankings for occurrence, severity and detection.
When the multiplication is complete, every potential cause of failure will have a risk priority number between 0 and 1,000. The largest numbers represent the potential errors that make the process most vulnerable. When a project team starts to improve a process, it focuses on the potential failures with the highest risk priority numbers first.
Using the FMEA methodology to assess every step of the production process helps project teams identify the most likely sources of failure. Experienced Six Sigma project teams know that of the three elements that make up the risk potential number (detection, severity and occurrence) addressing occurrence will have the biggest impact on the customer.
FMEA helps project teams identify the potential defects and failures caused a production process. It not only helps evaluate processes that produce errors, but also provides this information with a number that can be objectively understood and easily compared to other processes.
FMEA’s ability to measure the impact that the error has on the customer is in line with Six Sigma’s intense focus on improvement methods driven by the voice of the customer.
FMEA is considered by many to be the perfect Six Sigma tool.
