Lab_ FMEA_Failure Mode and Effect Anaylsis by hcj

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									LAB: FMEA (FAILURE MODE AND EFFECT ANALYSIS)

OBJECTIVE:
FMEA Processes—As you should have already learned, FMEA is an excellent tool to guide one
through the process of identifying, categorizing, prioritizing and solving problems, or resolving
concerns. This lab will provide you experience in using an excellent brainstorming tool that is
helpful in the FMEA process.

OVERVIEW:
An important part of FMEA is ensuring that, as much as possible, all possible issues or problems
have been identified. A good tool to use in doing that is a modified Affinity Diagram that we will
call—Post-it note brainstorming.

Advantages:                                          Disadvantages or limitations:
    Every person can be involved                        Without verbal clarification some
      without having to speak up or                        ideas may not be fully understood.
      verbally present his or her ideas and              Lack of open discussion early in the
      concerns.                                            process may limit new ideas that
    Even quiet people are fully involved                  sometimes come from hearing others
    More ideas can be generated in less                   ideas.
      time than most other methods.                      Must resist the temptation to hurry
    Everyone assists in categorizing                      the writing portion to ensure all ideas
      problems and issues.                                 are presented


PROCEDURE:
Step One
State the problem or issue to be discussed. It may be something like “What are the most severe
technical problems with the model A1 product?”
For this lab exercise the question is:
                “What are the most severe problems that could occur with a BBQ
                                           propane tank?”
Step Two
Each person writes one idea, solution, or item on a post-it note. One per note only
Step Three
Every item, idea, etc. is posted on a surface (wall, window, etc.) in random order.
Step Four
After all have posted everything they can think of (don’t rush this process) then the group
organizes the posted items into categories. The following rules apply:
    1. Any item can be moved by any person to any category or a new one started.
    2. If a moved item is felt by someone should be moved again, they are free to do so. If an
        item is beginning to be moved back and forth discussion between parties involved would
        help determine if a new item or category should be created.
Step Five
After categories have been created then the group should create labels for each category.
After labels have been created all in the group should review the categories and items in
categories to ensure that all agree with the categories.
This concludes the brainstorming exercise. The information now available is excellent material
generated by a group of people and categorized and labeled in a relatively short time. Groups as
large as 20 have done this exercise successfully.

To complete this lab exercise, do the following:
   1. Discuss the severity, occurrence and detectability of each of the categories of issues
      completed in the post-it note brainstorming exercise.
   2. As part of your lab write up discuss the priorities that were determined.
   3. Also discuss any suggestions you have to overcome the challenges listed.
   4. After completing the exercise for this lab, complete the report and include the following
       Your observations about the exercise
       What the technique (brainstorming) has taught you
       How brainstorming has a role in FMEA
       Observations regarding the FMEA process itself.

RESULTS:
Recommended Action(s)—When the failure modes have been rank ordered by RPN, corrective
action should be first directed at the highest ranked concerns and critical items. The intent of any
recommended action is to reduce any one or all of the occurrence, severity, and/or detection
rankings.

DISCUSSION:
    What are three advantages and three disadvantages about the team brainstorming session?
    Discuss the severity, occurrence and detectability of each of the categories of issues
      completed in the post-it note brainstorming.
    Discuss the priorities that ranked the highest. Were they what you would have expected?
    Discuss any suggestions you have for overcoming these high-ranking failure modes.
    Review the case study in the FMEA book on pages 45-53. Comment on the original
      severity, occurrence and detection rankings for the fire extinguisher.
    Do the categories that you listed indicate root causes or symptoms and why?
    If they are root causes how would you address them, if they were not root causes how
      would you find the root cause?
Evaluation Criteria Sheets
—to calculate the RPN                                      Failure Mode


                                                             Effect
        Failure                                           Severity: 1-10
     Something goes
        wrong

         Mode
     Cause of failure
                                                           Causes
         Effect
     Impact of cause                                   Occurrence: 1-10
        Analysis
   Careful &thoughtful
   evaluation of cause

                                                             Controls
                                                          Detection: 1-10




                                                       RPN = Severity X
                                                        Occurrence X
                                                          Detection

                            RISK PRIORITY NUMBER (RPN)

 The RISK PRIORITY NUMBER (RPN) is the product of the SEVERITY (S),
 OCCURRENCE (O), and DETECTION (D) ranking:

                                   RPN= (S) x (O) x (D)

 The RPN is a measure of design risk. The RPN is also used to rank order the concerns in
 processes (e.g., in Pareto fashion).
The RPN will be between “1” and “1,000.” For higher RPNs the team must undertake
efforts to reduce this calculation risk through corrective action(s).

                               DEFINING FMEA TERMS
                                    SEVERITY (S)

SEVERITY (S) is an assessment of the seriousness of the effect of the potential failure
mode. SEVERITY applies to the effect only. A reduction in SEVERITY ranking index
can be effected only through a design change. SEVERITY is estimated on a “1” to “10”
scale.
            EFFECT AND ANALYSIS METHODOLOGIES

                      SEVERITY (S) Evaluation Criteria

  Effect          Criteria: SEVERITY of Effect                                Ranking
Hazardous Very high severity ranking when a potential                           10
without   failure mode affects safe operation and/or
warning   involves noncompliance with regulations
          without warning.
Hazardous Very high severity ranking when a potential                              9
with      failure mode affects safe operation and/or
warning   involves noncompliance with regulations with
          warning
Very High Product/item inoperable, with loss of primary                            8
          function.
High      Product/item operable, but at reduced level of                           7
          performance. Customer dissatisfied.
Moderate Product/item operable, but may cause                                      6
          rework/repair and/or damage to equipment
Low       Product/item operable, but may cause slight                              5
          inconvenience to related operations.
Very Low Product/item operable, but possesses some                                 4
          defects (aesthetic and otherwise) noticeable to
          most customers.
Minor     Product/item operable, but may possess some                              3
          defects noticeable by discriminating customers.
Very      Product/item operable, but is in noncompliance                           2
Minor     with company policy.
None      No effect.                                                               1
                                             OCCURRENCE (O)

OCCURRENCE (O) is the likelihood that a specific cause/mechanism will occur.
OCCURRENCE (O) is estimated on a “1” to “10” scale.

                        OCCURRENCE (O) Evaluation Criteria

     Probability of Failure                           Possible Failure Rates                       Ranking
Very High: Failure is almost                          1 in 2                                        10
inevitable                                            1 in 3                                          9
High: Repeated Failures                               1 in 8                                          8
                                                      1 in 20                                         7
Moderate: Occasional Failures                         1 in 80                                         6
                                                      1 in 400                                        5
                                                      1 in 2,000                                      4
Low: Relatively Few Failures                          1 in 15,000                                     3
                                                      1 in 150,000                                    2
Remote: Failure is Unlikely                           1 in 1,500,000                                 1

    NOTE: The team should agree on an evaluation criteria and
          ranking system, which is consistent, even if modified
          for individual product/process analysis.
                                              DETECTION (D)

    Detection (D) is an assessment of the ability of proposed  type (2) current design
    controls to detect a potential cause/mechanism (design weakness), or the ability of
    the proposed #type (3) current design controls to detect the subsequent failure
    mode, before the component, subsystem, or system is released for production. In
    order to achieve a lower ranking, generally the planned design control (e.g.,
    preventative, validation, and/or verification activities) has to be improved.
    Detection is estimated on a “1” to “10” scale.





 Type (2) Design Controls: Detect the cause/mechanism or failure mode/effect from occurring, or reduce their rate
of occurrence.
#Type (3) Design Controls: Detect the failure mode.

                    DETECTION (D) Evaluation Criteria
  Detection         Criteria: Likelihood of Detection by Design     Ranking
                                        Control
Absolute          Design Control will not and/or cannot detect a       10
Uncertainty       potential cause/mechanism and subsequent
                  failure mode; or there is no Design Control.
Very Remote       Very remote chance the Design Control will           9
                  detect a potential cause/mechanism and
                  subsequent failure mode.
Remote            Remote chance the Design Control will detect a       8
                  potential cause/mechanism and subsequent
                  failure mode.
Very Low          Very Low chance the Design Control will detect       7
                  a potential cause/mechanism and subsequent
                  failure mode.
Low               Low chance the Design Control will detect a          6
                  potential cause/mechanism and subsequent
                  failure mode.
Moderate          Moderate chance the Design Control will detect       5
                  a potential cause/mechanism and subsequent
                  failure mode.
Moderately        Moderately high chance the Design Control will       4
High              detect a potential cause/mechanism and
                  subsequent failure mode.
High              High chance the Design Control will detect a         3
                  potential cause/mechanism and subsequent
                  failure mode.
Very High         Very High chance the Design Control will detect      2
                  a potential cause/mechanism and subsequent
                  failure mode
Almost            Design Control will almost certainly detect a        1
Certain           potential cause/mechanism and subsequent
                  failure mode

NOTE: Make sure team members agree on the evaluation criteria and
ranking system, which is consistent, even if modified for individual product
analysis

								
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