Discussion in 'FMEA - Failure Modes and Effects Analysis' started by John Michael Kane, Mar 6, 2019.
what exactly does "Class" mean in FMEA?
Page 91 of the current AIAG manual defines "classification" as (paraphrased) highlight high priority failure modes or identifying important characteristics...
Just to add. The Classification column can also be used to classify any special product or process characteristics (e.g. safety, special, critical, key, major, significant). The Special Characteristic Classification column of the Control Plan should be taken into account when accomplishing the Classification column of the FMEA. Customer symbols (e.g. Chrysler's Shield, Ford's Inverted Delta, GM's Diamond) to identify special characteristics can be used as entries in the Classification column.
Organizations can also develop their own classification. See the Classification Matrix below:
Those who use FMEAs need to learn that the classification value is more important than the RPN. Study the table below:
In this example, the RPN of 96 has less priority. However, the Classification Matrix (above) indicates that Failure Mode 1 falls within the Significant Zone, indicating a problem that will lead to significant vehicle/operation problem and cost the company money. Failure Mode 2 in this example shows an RPN of 160 that would raise flags for an auditor but doesn't fall into either the Critical Zone or Significant Zone.
If the organization prioritize Failure Mode 2 due to its higher RPN, then actions would be developed to either prevent a cause that rarely results in a defect or inspect for a defect that rarely happens. All this will be done while the process is rejecting at 1/500 of its products (based on criteria for evaluating Occurrence) without any signs that action is needed.
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