Machinery Lubrication

Machinery Lubrication May-June 2021

Machinery Lubrication magazine published by Noria Corporation

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www.machinerylubrication.com | May - June 2021 | 35 ML maintenance and storeroom operation. e opposite of that tells me that I might need to consider buying a house near that plant — I'm going to be there awhile. Metaphorically, get on the bathroom scale. What do you weigh? Where are you? "Own" that weight and do something about it. Even if you know where you're going, you're still lost if you don't know where you are. If you don't accept where you are, you, my new friends, are lost. Lube storage is not my message — my message is as follows: it is time to "own" where we are relative to our lubrication documentation and application and to move (incrementally) from 1.00 to 1.01. Consider this humble graphic. Simply a bolt with eight nuts. Each nut is individually labeled to infer that they should run down the bolt in order and sequence. I have not checked the math on this, but I'd stake my good name that it is correct (or really, really close). Accordingly, there is exactly one way to take this assembly apart. But, as the math goes, there are approximately 40,000+ ways to reassemble it. Ostensibly, someone could assemble it wrong with the nuts in the wrong order. Keep in mind — the "right" way refers to the process that produces the optimum result. is will look different for every machine and all its individual parts. If you were given the task of assembling the system as intended without an instructor, or worse, bad instructions, what are the chances that the result would be optimal? Or the result would be acceptable, or the time to complete the task acceptable, or the quality of the work well within tolerance, all with a favorable review from the customer? Not good, I'd venture. I want to interject a little literary license here and mention that I might use "chances," "probability," "likelihood" and "odds" as synonyms. A little projection is necessary for this next bit: imagine you are responsible for all aspects of machine lubrication, starting (as it always does) with lubrication selection and storage. In your new role, you are pleased to find that you actually have a dedicated oiler. We'll call him Leroy (note to the reader, Leroy was my very first dedicated oiler in my career). Although he's hard-working and well-intended, he's also poorly trained. You ask Leroy to take over full ownership of the lubrication program — from selection to storage to application. If he needs you, tell him you'll likely be in a meeting (high probability), but you'll get back with him when you can. You just gave Leroy a bolt and eight nuts and told him, "Good luck." In his best-selling work "Maintenance and Reliability Best Prac- tices," Ramesh Gulati introduces us to the concept of Reliability Block Diagrams, or RBD. Ramesh offers some graduate-level insight on how to calculate an asset's reliability, but for shop-floor practitioners such as us, it's really the RBD idea that we need to know for this discussion. Here is a simple, series arrangement of assets, with each machine's reliability value shown in the blocks: Node 1 Block 1 Block 2 Block 3 Node 2 0.85 0.80 0.90 Mr. Gulati tells us that the overall system reliability for a series configuration can be calculated as: R1 X R2 X R3 e result for our example is: 0.612 or 61.2% Here is a slightly more complex example, taking into account the redundant nature of parallel systems: Node 1 Block 1 Block 2 Block 3 Node 2 0.85 0.80 0.90 The overall system reliability for this parallel arrangement is calculated as: 1-[(1-R1) X (1-R2) X (1-R3)] e result for our example is: 0.997 or 99.7% Upping our education just a few notches more, and we can calculate the overall system reliability for a very complex (series and parallel) arrangement. For example: Node 1 Block 1 Block 1 Block 2 Block 2 Block 3 Block 3 Node 2 0.85 0.85 0.80 0.80 0.90 0.90 Hint: solve the parallel system first and then put the result in series with the other blocks. e result for this example is an overall system reliability of 0.61 or 61% It would be very fair for you to ask at this point, "What in the world has this got to do with lubrication? Or anything for that matter?" Fair enough. I believe that the same reliability block diagram can be used to calculate the overall reliability for all systems, not just for machines connected together.

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