(Illustration) Measure Step-4

Measure step - 4

Instructor : The last tool we are going to look at is a Failure Modes and Effects Analysis, or FMEA, for short. FMEA is
Instructor : a structured approach to identifying the ways in which a process can fail to meet critical customer requirements, estimating the risk of specific causes with regard to these failures,
Instructor : Evaluating the current control plan for preventing these failures from occurring, and
Instructor : Prioritizing the actions that should be taken to improve the process. FMEA is an ideal approach to documenting and tracking risk reduction actions, particularly when the consequence of a failure is severe.

Instructor : There are a number of terms that have specific definitions when used in the context of an FMEA. These are three of the most critical.
Instructor : The Failure Mode describes how a part or process can fail to meet the specification. This is usually associated with a defect or nonconformance. Going back to the car example mentioned earlier, the failure mode would be brake malfunctioning.
Instructor : A cause describes a deficiency that results in a Failure Mode. Causes are sources of Variability associated with Key Process Input Variables. For example no brake fluid would cause the malfunction.
Instructor : The Effect describes the impact on a customer if the Failure Mode is not prevented or corrected. The customer can be downstream or the ultimate customer. In the car example the effect of brake malfunction could be quite severe, even fatal.

Instructor : So how does the FMEA work? In short, it identifies ways in which a product or process can fail, and then plans how to prevent those failures. The key steps are
Instructor : Identify potential failure modes
Instructor : Rate the severity of their effect
Instructor : Evaluate objectively the probability of occurrence of causes and the ability to detect the cause when it occurs.
Instructor : Rank the risk of failure modes according to a numerical index called the Risk Priority Number, or RPN for short.
Instructor : And, focus on eliminating product and process concerns and help prevent problems from occurring.

Instructor : The overall FMEA goal, much like the goal of a fishbone diagram, is to link the causes, via the Failure Modes, to the potential effects over a time span. Next, we'll look at exactly how you do this using the FMEA document.

Instructor : Now that you understand the FMEA purpose and process at a high level, in the next few screens we'll take a look at the entire F M E A process, from preparation through improvement. Throughout this section, remember that the FMEA is a living document that will be used throughout the life of the product or process, not just for this six sigma project.
Instructor : While we will start putting the FMEA together in this phase, some of the information will be added in the Analyze, Improve, and Control phases. So even though we are going to look at each area of the FMEA form in this section, you will fill in various parts of it throughout your Six Sigma project.

Instructor : FMEA completion begins with Preparation.
Instructor : First, you must select a process team.
Instructor : The team then develops a process map and identifies the process steps; this helps to define the scope of the FMEA.
Instructor : Next list the key process outputs necessary to satisfy internal and external customer requirements; this helps to define what is and is not a Failure Mode.
Instructor : Then list the key process inputs for each process step,
Instructor : and define the relationships of the product outputs to process variables; this helps to determine the effects and causes for the corresponding Failure Modes.
Instructor : And finally, rank the inputs according to importance in order to determine the severity of the risk.

Instructor : With all the preparation complete, you can address the heart of the FMEA process. Let's recap those steps in detail.
Instructor : List the ways process inputs, or causes, can vary, along with any other sources of variability, and identify associated Failure Modes and Effects.
Instructor : Assign severity, occurrence and detection rating to each cause, and calculate the Risk Priority Number for each potential failure mode scenario.
Instructor : After performing the FMEA, it's time to address the necessary improvements.
Instructor : Begin by determining the actions your team recommends to reduce the RPNs.
Instructor : Then establish timeframes for corrective action.
Instructor : Take the appropriate actions and put controls into place.
Instructor : Finally, recalculate the RPNs.

Instructor : We are going to use a simple example of an FMEA and show you how the Risk Priority Number can be calculated. We are going to look at our drive to work. Let's start by filling in the first row of our FMEA. The first step is to define the first process step and its potential failure modes.
Instructor : The first entry we make is in the Process Step or Part Number column.
Instructor : This column defines the specific process steps or individual parts we are going to examine.
Instructor : In this case, we will look at starting the vehicle as our first process step. The second column is labeled Potential Failure Mode.
Instructor : This is where we define what can go wrong, or otherwise result in a defect.
Instructor : Our first failure mode is simply when the vehicle won't start.
Instructor : The third column is labeled Potential Failure Effects
Instructor : This is where we will define the impact of the failure mode upon the customer.
Instructor : In this case, the effect is that the driver cannot get to work.
Instructor : The fourth column is labeled S E V, for Degree of Severity.
Instructor : In other words, how severe is the effect on the customer?
Instructor : In this case, we will use the scale previously displayed in the Tell Me More example, and say that the degree of severity is seven, high degree of customer dissatisfaction due to the loss of function without a negative impact on safety. This degree of severity will cover all of the various potential causes because it's linked to the failure mode, not one of the specific causes.

Instructor : The Fifth column is the Potential Causes column.
Instructor : This column is where you list the possible causes of the failure mode.
Instructor : In this case, we have listed two possible causes, being out of fuel and a dead battery, for the failure mode Vehicle won't start. You may often list more than one cause for a given failure mode.
Instructor : The column labeled O C C is where we put another score.
Instructor : This score is the Likelihood of the specific failure mode occurring due to that specific cause. It is based on the ratings standards you saw in the previous Tell Me More. This file is also available in the Tools section.
Instructor : In this case we have assigned a score of three, or a low failure rate, to the vehicle failing to start because it's out of fuel and a six, or a moderate failure rate, for the vehicle failing to start because of a dead battery.
Instructor : The next column is labeled current controls.
Instructor : It asks you to describe the current controls which would act to prevent the specific failure mode from the cause listed.
Instructor : In this example, we have Observe Fuel Gauge as the control to prevent failure to start due to being out of fuel and Check Battery Life as the control to prevent failure due to a dead battery.
Instructor : Next we have the D E T, or Ability to Detect field.
Instructor : This is where we enter a score indicating how well one can detect the Cause or Failure Mode.
Instructor : We have given watching the fuel gauge a score of two, indicating almost certainty that the cause of the failure will be detected. The control of checking the battery life receives a score of eight, which indicates that there is a very low likelihood that the potential failure will be detected before reaching the next step.
Instructor : The next column documents the RPN or the Risk Priority Number. RPN is an index used to evaluate the risk of the failure mode associated with the potential causes and corresponding controls. Risk reduction plan should be initiated to address those items with high R P Ns. This is an index that can be used to prioritize our project focus.
Instructor : This number is calculated from the three previous scores entered in the Severity, Likelihood of Occurrence, and the Ability to Detect columns. By multiplying those three numbers together we get a final result.
Instructor : Let me show you how to calculate the RPN associated with running out of fuel. Take severity rating from the SEV column multiply by the occurrence rating from the OCC column the delectability rating from the DET column
Instructor : This results in a RPN of 42
Instructor : In this case, the RPN score for failing to start by running out of fuel is much lower than the score for failing to start due to a dead battery. This would indicate that the second cause is at a higher risk and a corresponding risk reduction plan should be produced.
Instructor : The remaining sections of the FMEA should be used to document the identified solutions to reduce the risks. The RPN score should also be revised after the implementation of the risk reduction plan.

Instructor : The Risk Priority Number is calculated by taking the products of the Severity score, the Likelihood of Occurrence score, and the Ability to Detect score.
Instructor : In the case of one failure mode, all of the severity scores will be the same. In this case, they are seven.
Instructor : We regarded to likelihood of occurrence much higher for the dead battery than the fuel outage, so its score is higher.
Instructor : Likewise, we regarded the chance of the controls failing to detect the problem in advance to be far worse for the battery than the fuel level, so that cause also got a higher Detect score.
Instructor : If we multiply the three scores in each column, we come up with a Risk Priority Number, or RPN, of 42 for the vehicle failing to start due to an undetected fuel outage and 336 for the same failure due to an undetected dead battery.