Machinery Lubrication

Machinery Lubrication May-June 2017

Machinery Lubrication magazine published by Noria Corporation

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M a i n t e n a n c e a n d R e l i a b i l i t y N o warning or short- warning failures are the worst kind. Think of a tire. It can wear out slowly over thousands of driving miles or rupture suddenly, at full highway speed, from a random piece of road debris. You can monitor tread loss over time and conveniently schedule a tire change. Conversely, who could predict the sudden appearance of a sharp piece of iron? Fault bubbles are sudden-death condi- tions in waiting. They haven't ruptured, but they are about to. Similar to a tire, fault bubbles can burst instantly. Unlike the tire, most fault bubbles in industrial machinery can be revealed by condition monitoring, which includes the careful examination by a skilled inspector. Once detected, the root cause can be arrested or at least mitigated. In past columns, I've mentioned the P-F interval. As a review, "P" is the point at which a failure (in progress) is first detected, while "F" is the end point of functional inoperability. Although the P-F interval is a theoretical concept that has useful application, it is rarely applied in real-world machines. This is because the real world comes with many variable events. These events distort the predict- ability of the P-F interval. Simply stated, the P-F interval is not well-behaved. It is a time interval that is influenced by detection skill and frequency. It is also influenced by multiple operational factors that determine the failure develop- ment period. These include: AS I SEE IT Jim Fi t ch | Nori a Corpor at ioN PROACTIVE to Avoid Root Cause FAULT BUBBLES 2 | May - June 2017 | Be

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