Daryl,
I am glad you chipped in. I tried explaining this point to Rolly and others but have evidently failed completely.
Many of us do not differentiate between planned and unplanned breakdowns - there is even a book called Zero Breakdowns which does not explain the difference. That unplanned breakdowns should be eliminated should not be in question, but the idea of planned breakdowns seems difficult to some of us. The concept of managing degradation and allowing breakdowns when failure consequences are low also appears difficult.

Mike-the-MW, may I suggest that you have not fully understood how RCM works? The purpose of RCM is to minimize risks associated with equipment failure. For this we evaluate the failure frequency and consequence to decide the risk level. We allow low risk level failuress to occur, i.e. planned breakdowns, since they dont matter. For the rest, where risks are not low, we find the right task and its frequency to lower the risk. The result is higher reliability and fewer failures. It so happens that when we lower risks, we lower maintenance costs, get higher uptime and higher safety levels. But the objective of RCM is NOT to lower costs per se, even though that is the natural outcome. Unfortunately, a number of RCM Consultants also plug the 'lowering cost' line without explaining how it is done. That, incidentally, happens to appeal to managements, so the myth that RCM is aimed at lowering costs gets established.

This message has been edited. Last edited by: Vee,

quote:

in many cases you are now managing the failures, not eliminating them altogether

Well, for parts with wear yes (condition and time monitored). But for operation, security and ambiental failures (unknow, fear, stress, etc.) I would say eliminated failures and so managing the consequences of failures.

Cristian

Robbie,

I don't think I actually did say this.

quote:

So what you are saying is that if I know there is some potential (random possibility) a bird might strike a plane and the effect is that it will crash, the fact that I knew it might happen makes it a planned failure?

So I agree, random failure happens.

By the way - Well done Cristian, represents a well implemented project and good leadership on your behalf.

This message has been edited. Last edited by: <Ozgipsy>,

I just think that the misconception between planned and unplanned breakdowns is often misinterpreted. In addition I believe that there are no planned breakdowns. I would let something breakdown if the consequences warrant the breakdown but I would never call it planned especially if I didn't know when it will happen (random failure). I would hate to be the maintenance manager who had to explain that it was a planned breakdown when the equipment goes down. And there are times when you have to run to failure even if the effect is downtime because sometimes the cost of trying to do away with the failure costs more than the effects even over a long period of time. No process is breakdown free. You might be able to achieve it for a short time but you cannot cheat the reaper forever. I also think that zero breakdowns eludes to operation and misses the whole other side of the world of functions that are not directly operation related.

Robbie,

quote:

In addition I believe that there are no planned breakdowns. I would let something breakdown if the consequences warrant the breakdown but I would never call it planned especially if I didn't know when it will happen (random failure).

Planning: a process of thinking, evaluating the risks and finding solutions. Maintenance Planning requires us to decide What task to do, When or how often to do it and How to do it (process steps) including the evaluation of resources, spares, logistic support etc.
Scheduling: a process to determine the best time to do a job, so that losses are kept to a minimum. Typically we look for opportunity windows where production losses are kept as low as possible.

Breakdowns can be aforethought, as when we decide to let equipment run to failure. Such events can be planned in detail, deciding the task, process steps to use, spares, tools and materials required, logistic support required etc. They cannot be scheduled because we dont know when they will happen. But when that does occur, we should know everything we need to, and mobilize quickly. So we can't schedule, but we can plan such breakdowns.

Against this we have unplanned breakdowns, where the cause of failure occurs randomly, a la nail in tire, or bird strike in an aircraft. We also have unplanned breakdowns caused by events that have random timing, not causes, as in the case of ball bearings or many of the 89% in the Nowlan & Heap study. Now these can often be condition-monitored, so we can prevent functional failure by intervening in time. Note that in this case the physical failure has already commenced (that is why we can monitor condition), but by predicting the time of failure, we can now schedule an event which we have - hopefully planned for, so we know already what spares, resources, tools etc. that we need.

Planning and scheduling are two distinct processes and we should not mistake one for the other.

It still leans to my point that no matter how much you prepare there will still be failures that will cause some amount of downtime when you don't want it. I am not talking about planning and scheduling. I only talked about planned and unplanned because of someone else's reference to it. I am talking about the reference of zero breakdowns and what others have connected to planned breakdowns. Any way you call it you cannot feasibly avoid all breakdowns and will have to accept some because they are not predictable based on time and are not predictable because of the lack of warning signs.

Yes Robbie however where there is a critical consequence failure must be eliminated.

Mike.

quote:

Originally posted by mike66:
Yes Robbie however where there is a critical consequence failure must be eliminated.

Mike.

I actually addressed the consequence issue in an earlier post. I agree to the extent that if it is feasible it must be eliminated. Sometimes it just can't happen.

quote:

Originally posted by Vee:
Mike-the-MW, may I suggest that you have not fully understood how RCM works?

You can not only suggest it - I'd agree with you.

quote:

The purpose of RCM is to minimize risks associated with equipment failure. For this we evaluate the failure frequency and consequence to decide the risk level. We allow low risk level failuress to occur, i.e. planned breakdowns, since they dont matter.

This doesn't seem to match what I have read about RCM. From what I can figure, looking at RCM in its initial incarnation as the type of maintenance performed on aircraft starting with the 747 (though it wasn't called RCM at the time) they figured out that the majority of components on aircraft exhibited failure type 'F' which is typified by a high 'infant mortality rate' which levels off. Replacing these components while they are still functioning _increases_ the chance of failure. It doesn't matter whether it's an SSR to run the fire extinguishers in the engines or an SSR to run the 'no smoking' lights, it has the same chance of failure, and neither are subject to time-based replacement. When they fail, they fail. If it's important then you add parallel systems as a failsafe. RCM works with aircraft because aircraft have a high basic equipment condition, and pilots care a lot more about the state of the aircraft they fly than the troglodytes who operate the machines that _I_ have to maintain care about my machines. If I tried to use RCM at my plant I'd go insane. TPM works better for me because I have a LOT of pumps and other time-failure components, and a relatively low basic operating condition due to budget constraints and operators who do horrible things to the machines.

quote:

For the rest, where risks are not low, we find the right task and its frequency to lower the risk.

Okay, so what would be the 'right task' for my example of a tire blowing from driving over a nail? A blowout on a front tire could cause a car to careen off the road, killing the occupants. Pretty high risk potential.

quote:

I actually addressed the consequence issue in an earlier post. I agree to the extent that if it is feasible it must be eliminated. Sometimes it just can't happen.

No Robbie it must happen. If you can't eliminate it you must redesign out the failure mode all together. The outcome of a failure with safety,environmental or catastophic level failure is not acceptable within any industry and I suggest if it is just accepted as inevitable by any organisation they are going to be held accountable.
I understand where you are coming from in that there is always the chance a lightning strike or tornado could take out an entire building and kill people in the process but usually a one of rare instance that has not been thought through and incorporated into a PM strategy would generally be seen with in an "act of God" context.

Why maintenance exists?
- To safeguard technical integrity.

What is technical integrity?
-Technical integrity is achieved when there are no foreseeable risks endangering the safety, environment and the asset value under specified operating conditions.

So Maintenance is part of risk management. So manage risk to as low as acceptable to business.

quote:

Originally posted by Josh:
So Maintenance is part of risk management. So manage risk to as low as acceptable to business.

That's the best point made so far - risk management is all about lowering it to an _acceptable_ level. Zero is expensive. We wouldn't have actuaries working diligently to put a dollar value on human life and suffering if this wasn't true.

One comment regarding the run to failure for small pumps less than 15kW, if the failure is one in a blue moon, it's ok but if the failure is quite frequent, it seems cannot be run to failure anymore because it become a high maintenance cost item.

Dear All,

Let me put in my response to my own opinion, understanding and perspective, here is the original question so far. I highly respect and value your response,

quote:

So which one of this statement is correct ?

1st : We can definetly eliminate failures by analyzing them through RCFA and RCA .

2nd : We cannot eliminate the likelihood of a failure, but rather we can only prevent or predict the failure from occuring.

3rd : Failures cannot be eliminated and the best that maintenance can do is to reduce them.

4rth : Failures cannot be eliminated the best that maintenance can do is to prolong or delay the process of failure itself.

First of all, let me tell you good people that all failures are not created equal (depends upon the consequence). And that failure itself is broad and diversified, sometimes confusion arise as when do we call it a failure, before answering my question, I would like to explain failure in the way I have research and understand it.

A) Patterns of Failure (How Failure Occurs)
Infant Mortality Failures - These are failures that occur at the the beginning of its life.

Random Failures - These are failures that can occur at any given period, and this is where our routine Preventive Maintenance will be at its weakest point, recommended task that can be used for Random failures will be Predictive Maintenance if the failure provides a warning or potential failure, modification or simply run it until it fails if the consequences and risk will be low.

Wear Out Failures or age related failures where parts will eventually survive to the age that it is suppose to fail

Now Moubray studies that these three failures mostly occur in combination by studing parts behavior and led to what we call the 6 failure pattern, But eventually those 3 patterns of failure (bathtub curve) can be seen as existing in TPM books, statistic books and Weibull.

B) Failures Can Be Classified as follows :
Also from the book of Moubray we have
- Hidden Failures, failures that will not become evident to the operator or mainteance when it occurs on its own such as failure of a standby pump with the duty pump running

- Evident Failures, are failures that will become evident to the operator and maintenance when it occurs on its own

C)We can also have different Types of Faiures :
- Function Loss Failure - or failure of the primary function, wherien when a failure occurs the equipment will totally stop and affect operations

- Function Loss Reduction - or failure of secondary functions wherein when a failure occurs then equipment can still be capable of running. Every equipment have their own primary and secondary functions that we must be aware at.

D) Now from the TPM Books and references breakdowns can be Planned or Unplanned and what maintenance can prevent or eliminate or zero out is the unplanned breakdown. Note : TPM originated from the Japanese and their terms might not really concurr with us, they use the term Planned and Unplanned breakdowns. So let us just respect their terminlogies for now as othes might disagree.


Planning for an activity to be performed on our equipment, such as Preventive Maintenance, parts replacement constitute the Planned Breakdown, or PdM group spotting that a potential failure is now in progress and the next step is scheduling the equipment for some intervention. While Unplanned Breakdown simply means that when failure occurs we are unaware and are always caught by surprise on its occurance.

So which one of this statement is correct ?

1st : We can definetly eliminate failures by analyzing them through RCFA and RCA .

My reply : Wrong !!! Failures cannot be totally elimated by analyzing them through RCFA and RCA. There are a variety of causes to understand and analyze and every single failure have their own unique causes and when we only treat a single cause then there is a likelihood of that same part to fail again in the future due to a different cause, remember when we speak about Root Cause Failure Analysis and Root Cause Analysis, we are dealing with evidences as to what really have caused the part to fail and not all the probable causes that might cause the part to fail.

As my good and dear friend Bob Nelms from Failsafe-Network once told me that you cannot remove an ocean with a fork (not even a spoon)
simply concurrs that it is possible to remove or eliminate the cause but not the failure itself.

A bearing can fail for a multiple variety of reasons and taking care only on a single cause (perhaps the analysis shows that bearing failure was due to lubrication failure) will not eliminate its occurance since it can fail in the future due to some other reasons such as brinelling, pitting fatigue, spalling, misalignment, careless handling, overlube, underlube, dirt, etc.

RCM was founded on the belief that its purpose was to eliminated / reduce plane crashes per million take-offs by studing every single part and its behavior. Today, plane still crashes for some other reasons such as terrorism.

I will write my remaining conclusion soon.

My Warm Regards,

This message has been edited. Last edited by: Rolly12,

quote:

Originally posted by mike66:

No Robbie it must happen. If you can't eliminate it you must redesign out the failure mode all together. The outcome of a failure with safety,environmental or catastophic level failure is not acceptable within any industry and I suggest if it is just accepted as inevitable by any organisation they are going to be held accountable.
I understand where you are coming from in that there is always the chance a lightning strike or tornado could take out an entire building and kill people in the process but usually a one of rare instance that has not been thought through and incorporated into a PM strategy would generally be seen with in an "act of God" context.

What about the space shuttle program? There are several risks taken including the tiles which have proven to be a catastrophic failure. There always has to be some acceptable level of risk and you will not be able to eliminate all risk. If there is a risk that cannot be eliminated cost effectively should a company close all together? We would not be where we are today if we did not accept some level of risk in everything we do. I agree though, if you can effectively eliminate a failure mode with critical consequences within the ability to still be able to be in business than do it.

Josh,

I am not sure I agree with this statement.

quote:

Why maintenance exists?
- To safeguard technical integrity.

As stated within this thread the technical integrity may not be worth safeguarding in some cases. (RTF strategies)

We do maintenance because assets fail, and assets fail because thats the way the universe works.

Check this out: www.secondlaw.com

hehe - thanks Robbie - but the space shuttle program is not what I would call a typical industry - the risks associated with being an astronaunt require a different set of rules and I'm sure their life insurance policies take that into account.

Mike.

Dear All,

Let me conclude my discussion here as to what I think is most relevant and appropriate :

1st : We can definetly eliminate failures by analyzing them through RCFA and RCA .

My reply :

Wrong !!! Failures cannot be totally elimated by analyzing them through RCFA and RCA. There are a variety of causes to understand and analyze and every single failure have their own unique causes and when we only treat a single cause then there is a likelihood of that same part to fail again in the future due to a different cause, remember when we speak about Root Cause Failure Analysis and Root Cause Analysis, we are dealing with evidences as to what really have caused the part to fail and not all the probable causes that might cause the part to fail.

As my good and dear friend Bob Nelms from Failsafe-Network once told me that you cannot remove an ocean with a fork (not even a spoon)
simply concurrs that it is possible to remove or eliminate the cause but not the failure itself.

A bearing can fail for a multiple variety of reasons and taking care only on a single cause (perhaps the analysis shows that bearing failure was due to lubrication failure) will not eliminate its occurance since it can fail in the future due to some other reasons such as brinelling, pitting fatigue, spalling, misalignment, careless handling, overlube, underlube, dirt, etc.

RCM was founded on the belief that its purpose was to eliminated / reduce plane crashes per million take-offs by studing every single part and its behavior. Today, plane still crashes for some other reasons such as terrorism.


2nd : We cannot eliminate the likelihood of a failure, but rather we can only prevent or predict the failure from occuring.

Yes, it is possible to prevent failures for age related patterns which are around 15 to 20% of overall equipment failures and predict failures for those who inhibit signs of potential failure.

But this is not the goal of maintenance, if a bearing fails prematurely, yes we can predict that it is on the verge of failing, but the life of the bearing had not been maximized but only predicted in advance. Not all failures can be predicted and prevented.

3rd : Failures cannot be eliminated and the best that maintenance can do is to reduce them.

Wrong !!! Some think that when we have experience zero unplanned breakdown or have reduced failure tremendously as per seen on our breakdown indices for the past couple of years, but have we have really eliminated the likelihood of a failure ? No, this is not true, it will occur but on a delayed process, we are just delaying the process of failure

4rth : Failures cannot be eliminated the best that maintenance can do is to prolong or delay the process of failure itself.

Correct !!! I think that we must not be misled that maintenance can eliminate failures, they will happen and they will occur, the best that we can do is to delay its process, control the timing of failure or eventually prolong the occurrence of failure, yet in the end failure and breakdowns will do occur on the equipment.

Conclusion :

Failures cannot be eliminated and failures vary in consequences, the best the we maintenance and reliability people can do is to delay the process of failure and control the timing of failure but eventually and inevitably expect failure to occur in the future.

If you are experiencing a no failure situation in you equipment, it is just temporary, because of your good system of maintenance you are only delaying the process of failure.

I've been in the field of TPM for so many years and its goal is to zero out unplanned breakdowns is idealistic and in its technical sense next to impossible if we really understand how part really behaves, when parts wear out, in its technical sense it failed. Hence, we are not really eliminating failure itself but just doing the best we can do to prolong the life of the part or component.

Kindly click this link to accept my acknowledgment for those who have replied on this thread.

http://www.rsareliability.com/newsletterjune2007issue.htm

My Warm Regards,

This message has been edited. Last edited by: Rolly12,