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Does Test Equipment Failure Affect FPY?

Six Sigma – iSixSigma Forums Operations Manufacturing Does Test Equipment Failure Affect FPY?

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  • #55799

    Daniel Wilson
    Participant

    I work in an HVAC manufacturing plant and recently joined their Quality Control team. One of my daily tasks is analyzing the previous day’s quality data and calculating FPY (among other metrics). At the end of our assembly line, our newly built hvac units are powered on and cycled through various functions to verify proper operation. The test operator connects sensors and and gauges to the unit before the test. During the test, values collected by the sensors and gauges are interpreted as a Pass or Fail by the test program. After the test is complete, the sensors and gauges are removed and the unit proceeds down the line.

    So my question is this: Do problems with test equipment count against FPY?

    For example, if while a unit is being tested, a temperature sensor that the operator connected goes bad or falls off and gives a false reading that subsequently “fails” the test, does this count against a true FPY? This is assuming that after replacing the sensor and restarting the test, it passes. Maybe it should also be noted that nothing has been added or changed with the unit during this process; it is only a test.

    My [limited] understanding of FPY is that it only counts units coming out of a process the first time, without rework or scrap, as a “pass”. Of course, the unit was functioning properly, requiring no rework or scrap; it was the test equipment that failed, and I’m not counting maintenance to the test equipment as rework or scrap, and so I’m inclined to leave it out of the equation.

    Maybe as a follow up question; what if the test operator simply forgot to connect a sensor and the test “failed” for that reason?

    I appreciate any clarity you can give

    -Daniel

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    #201768

    Strayer
    Participant

    No, it shouldn’t affect FPY since you’re measuring product yield, not your testing procedures. When a first pass fail is due to a recognized testing failure I’d say to test the unit again after the testing problem is corrected and use that as first pass. You might consider doing FMEA on your testing procedures and equipment since you recognize you have a problem.

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    #201778

    Strayer
    Participant

    On further thought. It depends on whether or not the finished goods inspection/test is considered part of the production process. If so, then yes it should affect FPY. My inclination is that it shouldn’t since it’s post-production. But on the other hand, a unit does not become part of the yield until it passes. Your organization should agree on which is the case. Don’t make this decision yourself.

    In either case you clearly have a reliability problem with your testing and you need to address that. Whether or not you agree that it affects FPY the false negative results are wasteful.

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    #201782

    Chris Seider
    Participant

    At a minimum, it might imply quality check results might be suspect right before failure? At least you’ve found an opportunity to attack–assuming it’s a good cost opportunity on the pareto or bottlenecking production.

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