Category Archives: Theory and definitions
Failure probability prior to attaining MTTF
The article “What is the scale parameter” showed that 63% of randomly failing items or items adhering to Weibull failure behavier will fail prior to attaining their MTTF. Generally speaking, the MTTF is not a good decision guide for the … Continue reading
Reliability trend yes Weibull analysis no
Building a Weibull model from a sample of data that covers a prolonged duration assumes that all failure times observed are “independently and identically distributed” (iid). That means that no change occurred in the inherent reliability of the item over … Continue reading
Diagnostics versus prognostics
Where is the divide between the process of troubleshooting and that of predictive condition based maintenance? Both sets of procedures require condition data and knowledge of failure behavior. How do these distinct processes work with one another? Some confusion in the … Continue reading
Posted in CBM, Theory and definitions
Tagged CBM, Potential failure, RULE, Terminology
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Achieving reliability from data
Which, among limitless, maintenance related data is relevant to physical asset reliability improvement? Secondly, how do we transform that data into decision models for effective risk management? Finally, how do we continuously update those models for verifiable asset reliability improvement? These questions drive our relentless pursuit of new maintenance … Continue reading
Posted in Reliability Analysis, Theory and definitions
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Random failure is exponential reliability decay
When something decays or grows “exponentially” it means that it changes regularly by a constant factor. An example of exponential growth is the principle in a compound interest bank account which increases at regular intervals by a constant factor. Assume that you … Continue reading