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Attain the double vision of reliability AND maintainability

Have you got double vision? I hope you do, but not in the sense I bet that you are thinking. No, I’m not talking about having one too many or that splitting headache that sometimes results in double vision. I’m talking about driving availability. It’s a measure that is made up of two component measures, mean time before failure (MTBF) and mean time to repair (MTTR).

The equation is Availability = MTBF / (MTBF + MTTR).

I hope you would agree that MTBF is a measure of reliability. Isn’t that one of the primary visions that you have for your organization, driving improved reliability? I happen to be working with a client this week in the heavy industrial sector on just that, an equipment reliability improvement effort that involves failure modes and effects analysis (FMEA) and other techniques.

What about MTTR? It’s a measure of maintainability, or the average (mean) amount of time required to complete the repair or restoration of a failed component. It’s more than just a second part of the Availability equation; it must be included as a separate integrated vision for your organization. The reality is that very little attention is paid to making equipment easy to maintain in many organizations. Yet, it’s quite easy to justify simple, often inexpensive modifications to new or existing equipment to make it maintenance friendly.

It happens that a piece of equipment that I was asked to include in the FMEA effort this week becomes a great example. A large hydraulic reservoir sits right above two large hydraulic pump/coupling/motor combinations. The pumps are sandwiched between the reservoir and the floor, not to mention surrounded on the sides by the framework holding the reservoir. The pumps service critical production equipment that operates 24/7. As the maintenance group is unable to service and align the assemblies, it has experienced the replacement of six $40,000 pumps in the last two years. Yes, I know, sometimes the obvious escapes us, or we don’t feel empowered to make the change, but that’s a different topic for another day. Interestingly, you can actually build-in addition parameters to your FMEA to create an index for maintainability that you can sort just like the risk probability number (RPN).

Everyone recognizes that there is a cost associated with downtime. Equipment that is difficult to maintain drives less reliability and only serves to extend the amount of downtime required to restore the equipment to operation. Create an environment that has a double vision – that of both reliability and maintainability – for a more comprehensive and effective approach.

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Filed Under: Featured, Featured Category, Maintenance Excellence    |  Tags: equipment failure, maintenance management, maintenance metrics, pumps, Reliability Engineering

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