This is a series of four steps in the Lean Six Sigma process of completing the Design phase of the DMAIC Six Sigma root cause analysis.  The four steps are the following:  SIPOC diagram, Input map, Cause and Effects (C&E) matrix, and the Failure Modes and Effects Analysis (FEMA).

Every product or process is subject to different types or modes of failure and the potential failures all have consequences or effects.   In this process, we identify the potential failures and the associated relative risks designed into a product or process, prioritize action plans to reduce those potential failures with the highest relative risk, and track and evaluate the results of the action plans.

  • Review and label the Process Steps (using your process map) and the intended function or functions of those steps
  • Consider the Potential Failure Modes for each component and its corresponding function, represents any manner in which the component or process step could fail to perform its intended function or functions.
  • Determine the Potential Failure Effects associated with each failure mode. This is directly related to the ability of that specific component to perform its intended function.
  • For each failure mode, determine all the Potential Root Causes.
  • For each cause, identify Current Process Controls and the measure that keeps the customer from receiving defect or failures.
  • Assign a Severity ranking to each effect that has been identified, an estimate of how serious an effect would be should it occur based on the impact the customer would notice.
  • The severity ranking is based on a relative scale ranging from 1 to 10, with a 10 meaning the highest level of risk.
  • Assign the Occurrence Ranking. The Occurrence ranking is based on the likelihood, or frequency, that the cause, failure, will occur. Sources of data may be scrap, rework reports, customer complaints, and equipment maintenance records.
  • Assign the Detection Rankings. Identify the process or product related controls in place for each failure mode. Controls can either prevent a failure from occurring or detect a failure mode, cause of failure, or effect of failure after it has occurred.
  • Calculate the Risk Priority Number (RPN). The higher the RPN, the higher the potential risk.   The RPN is calculated by multiplying the three rankings together.
  • Prioritize the Risks by Sorting the RPN from Highest Score to Lowest Score.
  • Develop Action Plan. Taking action means reducing the RPN.
  • Assign responsibility for each action and the deadline for the solution.
  • Take Action.
  • Recalculate the Resulting RPN. To recalculate the RPN, reassess the severity, occurrence, and detection rankings for the failure modes after the action plan has been completed.

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Gary Kapanowski – Lean Six Sigma Master Black Belt – Excelsior

The following blog is the opinion of Gary Kapanowski and  It is the sole intent to broadcast this opinion from Gary Kapanowski and exclusively and not to reflect on any other institutions or organizations associated with Gary Kapanowski or

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