The Fractal Solutions Blog

Function and Failure Modes - Important Factors in Reliability Centered Maintenance (RCM) Part I

Jan 25, 2018 10:30:00 AM / by Larry Johnson

mining-excavator-1736293_1280Equipment and manufacturing has been changing dramatically since the Industrial Revolution acted as a catalyst in the early 1800s, leading to evolution inmaintenance engineering. For example, re-thinking the idea of simply replacing worn out parts, with figuring out what would actually lengthen service life, like lubrication to reduce friction and wear and tear.

Nowadays, we refer to these kind of concepts as RCM or Reliability Centered Maintenance.
RCM allowed for a more detailed analysis into how we maintain machinery. Interestingly, (continuing with the above example), numerous studies actually concluded that wear and tear was only contributing to a small percentage of downtime, and that the parts usually wore out in a random failure distribution.

In this blog we are going to hone in on a few of the important factors and core concepts that can help us understand Reliability Centered Maintenance methodology and its study.

Equipment Function

Whenever we purchase an item, we want it to fulfill a certain function, similarly when we buy a piece of equipment, we want it for a specific purpose. In context, Amazon may buy a machine to wrap up their orders before they are shipped out to customers. So in the same way, every piece in our machinery is for a specific purpose.

But it is common for equipment to have more than one function, the primary one in our Amazon example, would be wrapping products, and the secondary or other function/s could be keeping the product contamination free and safely delivered to the customer unaltered.

Clearly defining and stating the function of the asset is vital, from specifying the purpose(s) of the asset (primary & secondary function), to quantifying what we expect the asset to do (production volume, for example).

Despite the function sounding easy to define, it is not always an easy task, and does require experience and knowhow. This function is always operating context-dependent, especially when defining and quantifying the performance, or expected performance.  

For example, you could have two pumps that are identical in a Nuclear Power Plant but have completely different functions, one used to pump cooling water to the core and the other to collect and transfer rainwater in a large facility. We can clearly see that two identical pumps have different uses and their operating context is different entirely, thus the maintenance approach to them will be unique.

Function Failure

When your asset fails to fulfill its function, it is defined as a functional failure, and this can become a total failure if the asset cannot perform at all. Or it can be a partial failure if the asset has a percentage of functionality, but below its standard output or capability.

Contextualized back to our prior Amazon example, if the machine is not producing packaging it would be a Total Functional Failure, but if it’s working and failing to maintain the standard output or below the required output, it would be a Functional Failure.

As before, the operational context is important to consider especially when defining a functional failure. The machine could still be wrapping the products, which depending on the day’s volume could be fine on certain days, but not in a busier period such as Christmas.

In part 2 of this blog we’ll look at Failure Modes, their effects and consequences.

Here at Fractal Solutions we are global leaders in asset management, RCM and equipment reliability. If you are interested in dicussing your asset management or reliability centered maintenance program, get in touch with one of our team using the button below:

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Written by Larry Johnson

Larry Johnson is the founder and president of Fractal Solutions.  He is an internationally known consultant, lecturer, and trainer in asset management and equipment reliability programs.

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