Page 42 - Root Cause Failure Analysis

Root Cause Failure Analysis Methodology 33

lubrication, adjustments, and other preventive tasks. Determine if these procedures
are being performed in a timely manner and if proper techniques are being used.

OBSERVATIONS AND MEASUREMENTS
If the application and maintenance reviews are not conclusive. additional evaluation
and testing may be necessary. The techniques discussed in this section provide ways
to quantify deviations from acceptable operating and maintenance practices. By using
these techniques, the investigating team can accurately establish deviations that may
be contributing to the problem.

After establishing potential deviations in the operating envelope or other variations
that may have contributed to the event, the next step is to verify that these factors were
actual contributors. The best method of confirmation is to physically measure the
operating dynamics of the machine or production system associated with the event.

Evaluating any event or incident that results in partial or complete failure of a
machine, piece of equipment, or system should include a thorough analysis of the
failed parts or components. The actual methods used will vary depending on the fail-
ure mode and the type of machine or component that failed.

In most cases, failed components must be replaced immediately to minimize the
impact on production. If this is the case, an evaluation of the system that surrounded
the incident may be beneficial. If this testing can be conducted shortly after replacing
the failed machine, there may be residual evidence that will aid in the investigation.
This is especially true in those cases where variations in operating parameters, such as
product variations and operating practices, contributed to the failure.

Many types of measurements can be taken and observations made, but the most effec-
tive include vibration analysis, quantification of process parameters, and visual
inspection. Vibration analysis, coupled with direct recording of process variables, pro-
vides the most effective means of determining their effect. A full multichannel analy-
sis of the replacement machine and its installed system provides the data required to
evaluate the potential contribution of the system to the failure.

Vibration Analysis

Vibration analysis is perhaps the best method of measuring the actual operating
dynamics of mechanical systems. This technique provides the means of quantifying a
variety of factors that may contribute to the event-even when equipment failure has
not occurred.

If variations in incoming product, operating or maintenance practices, ambient envi-
ronment, or a myriad or other variables are believed to be a contributing factor, vibra-
tion tests can measure the real effect of each variable.