IMC-2008 23rd International Maintenance Conference - Dec 8-11 - Hyatt Coconut Point Bonita Springs Florida Join or Manage Your Profile Posting Boards Maintenance and Reliability Posts About Improving Reliability What is Corrective Maintenance (CM)?
Join or Manage Your Profile Posting Boards Maintenance and Reliability Posts About Improving Reliability What is Corrective Maintenance (CM)?|
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I have been all over the world in the past 24 months to visit many different maintenance and reliability professionals. Many of them are kind enough to show me some details about the maintenance and reliability programs they are involved in.
We usually talk about planned and unplanned work and the topic of corrective maintenance usually arises. When I ask for the definition of corrective maintenance - I get as many different answers as people I speak with. Can someone in the forum please tell me if there is a proper definition of corrective maintenance and what it is? Links are OK but I prefer to have the discussion right here. Terry O |
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Wowza Terry. Looking for the "perfect and right" definition is always a daunting task. That's probably why dictionary.com lists so many different definitions for so many different words. The two I like most for the word "corrective" are: 1) tending or intended to correct or counteract or restore to a normal condition (cited from Wordnet), and 2) counteracting or modifying what is malfunctioning, undesirable, or injurious (cited from American Heritage Stedman's Medical Dictionary). Also, the word "corrective" has quite a few synonyms if you look it up in a thesaurus. The one I like the most is "punitive". Anyone out there partake in punitive maintenance?
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Terry - this topic was touched on by a thread originated by Jim Maslach on 12 July 2005. Here's an exerpt from Vee I will include which I think does it justice (hope you don't mind Vee):
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Just as an additional - I have been struggling for quite some time on the whole concept of corrective maintenance and what it is. It bugs me - however to reflect on Vee's definition has helped and I think the important thing is whatever def. you decide upon stick with it - it may not be the same globally and we may never have a global agreement on what it should be but if you are measuring it make sure you keep it the same within your four walls otherwise you will get into all sorts of strife.
I like the idea that it is an action initiated due to a measured/observed condition whether before or after functional failure. Mike. |
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Terry and All,
I have been teaching several plants and I often times here this word also Corrective Maintenance" and it spells different meanings for different types of plants. From the book of Tokutaro Suzuki, Senior Consultant from JIPM, TPM in Process Industries, he defined page 149 Corrective Maintenance improves equipment and its components so that preventive maintenance can be carried out reliability. Equipment with design weaknesses must be carried out. My understanding regarding Suzuki's definition is that from TPM's point of view corrective maintenance is also the same as proactive maintenance. However in other plants such as power plants, they termed corrective maintenance as doing repair works after a breakdown or failure had occured making it reactive in nature. Maintenance strateges have different terms : Reactive Maintenance : Also termed as Run to Fail, Run to Destruction, Breakdown Maintenance, Unplanned Maintenance, Band-Aid Maintenance, Firefighting Maintenance, Stop the Bleeding Maintenance, Mc Guyver Maintenance, No schedule maintenance (RCM Term), Unscheduled Outage, etc. Preventive Maintenance - Also termed as, Calendar-Based, Scheduled Maintenance, Time-Based Maintenance, Stroke Based Maintenance, Scheduled Discard, Schedule Restoration, Scheduled Outage and Corrective Maintenance for some industries Predictive Maintenance also termed as Condition-Based Maintenance, Reliability-Based Maitenance, On-Condition Tasks, Equipment Diagnostic Monitoring, Diagnostic Techniques, Non-destructive Testing etc. Proactive Maintenance - Modification, Redesign, Maintenance Prevention, Equipment improvement The way my understanding lies, there is no standard understanding of what corrective maintenance is, it can be proactive or reactive. My Warm Regards, |
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I'd like to see corrective maintenance split into two categories- planned and unplanned. Planned corrective maintenance indicates the work was performed before a breakdown occurred and unplanned indicates work was performed because a breakdown occurred.
It would be great to have a bucket for work performed because a PM discovered a deficiency, that would be planned CM work. CMP and CMU would give better definition of how your PM program is working. More CMPs and less CMUs means the program is working. Less CMPs and more CMUs means the program needs development. I forget what I just said, I wasn't listening. JW |
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Terry and others,
To correct something, we must already know that it is not performing as desired. That it is not performing can only be known if we 'measure' by sight, touch, smell or hearing (by human senses or with instruments) and we have an established set of performance standards. Prior knowledge is an essential element in determining whether it is corrective or otherwise. In contrast, 'Preventive' work is anticipatory, using design calculations,historical evidence, expert opinion or probabilistic predictions. Breakdown work may be based on predicting condition (when it is Corrective Maintenance or CM that has such low consequences that we allow it to run to failure), or because we had no prior knowledge of the condition. Thus Breakdown work may be 'planned' (when we decide to allow an item to run to failure) or unplanned,where we had no prior knowledge at all. I think Wally was referring to this aspect of BM in his post and I support his view. In this context, I like to think along the following lines - If a machine is not functioning, is it because: 1. We stopped it while it was running OK? That is PM, a planned activity. 2. We measured it to confirm possible loss of function? That is Condition Monitoring, a planned activity. If we can predict failure and intervene before that happens, it is CM. If we intervene after failure, it is a planned BM. 3. The machine stopped itself? Then it is unplanned BM. Mike makes a good point: once you agree on a definition, stick to it and don't keep changing it. Regards, V.Narayan (Vee) Lead Author, 100 Years of Maintenance: Practical Lessons from Three Lifetimes, Industrial Press.NY ISBN-13: 978-0831133238 Author, Effective Maintenance Management: Risk and Reliability Strategies for Optimizing Performance, 2004, Industrial Press NY ISBN-13: 978-0831131784 |
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In CMMS, we may use:
Breakdown Maintenance (BD) for unplanned total functional failure or planned run to failure. So it's important to distinguish them in maintenance activity type field. Corrective maintenance (CM) for normailizing partial functional failure ad-hocly and not found during PM. Corrective/preventive maintenance (CP) for normalizing partial functional failure found during preventive maintenance (PM). CP can indicate how efective the PM and its doer in detecting failures. How about corrective jobs found during daily walkarounds? If the daily walkaround is scheduled in CMMS, it's CP but if not scheduled in CMMS, it's CM. How about corrective jobs for abnormalities found by operators? It's CM! |
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Posted on behalf of Mac Smith
We use the following definition of preventive maintenance (PM): Preventive maintenance is the performance of inspection and/or servicing tasks that have been preplanned (i.e., scheduled) for accomplishment at specific points in time to retain the functional capabilities of operating equipment or systems. The word "preplanned" is the key element in developing a proactive maintenance mode and culture. In fact, this now provides us with a very clear and concise way to define corrective maintenance (CM): Corrective maintenance is the performance of unplanned (i.e., unexpected) maintenance tasks to restore the functional capabilities of failed or malfunctioning equipment or systems.As viewed by the authors, the entire world of maintenance activity is fully encompassed in these two definitions. |
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Dear All,
Once again, for the record, if we are in the east (Japan) mostly practicing TPM, then corrective maintenance is a good thing since these means improving something. On the other hand mostly from the west, corrective maintenance is not as good as the east thinks since this mostly refer to unplanned or unscheduled outage. My Warm Regards, |
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Rolly,
In my view, there is nothing inherently good or bad about Corrective Maintenance. It is simply a type of maintenance. All of the maintenance work we do must address the risks to the organization. These risks may affect Health, Safety, Environment, Profitability, Asset Life or Reputation. We choose our maintenance strategies to match the risk of failure (i.e probability and consequence). We can permit failures whose risks are low, i.e. run-to-failure or breakdown, because the combined risk of failure and adverse profitability is the lowest we can get. When risks are high, we opt for age-based (i.e time, cycles, starts etc) PM or condition-based (i.e PdM) strategies, depending on the failure distributions, or shape of the probability density curve. And if we cannot find a suitable task for high-risk failures, we have to redesign the process, equipment or retrain the people involved. In my view, we should move away from any dogma, when it comes to deciding on maintenance strategies and stick to the science that applies to maintenance. Regards, V.Narayan (Vee) Lead Author, 100 Years of Maintenance: Practical Lessons from Three Lifetimes, Industrial Press.NY ISBN-13: 978-0831133238 Author, Effective Maintenance Management: Risk and Reliability Strategies for Optimizing Performance, 2004, Industrial Press NY ISBN-13: 978-0831131784 |
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Dear Vee,
I agree totally with your thoughts, however, there is really no universal standard for maintenance task and the terms used vary from one type of industry to another. My views are based on my experience in what industry termed their tasks although they offered the same meaning. Even RCM use the word No Scheduled Maintenance instead of the most common Run To Fail which most industries know. When I work with the mining firm, the maintenance craftspeople use the term Run To Destruction and not Run to Fail. For TPM practicioners mostly those who have achieved JIPM awards level, they use the term corrective maintenance as performing modification and improvements. When I was consulting with some power plants here in our country, they used they term scheduled and unscheduled outage in which later on learned that unscheduled outage refers to corrective maintenance irregardless of the consequences whether of high or low risk. I apologize for sounding dogmatic but I am only basing these on the different terms industy use. Even John Moubray used different terms designating the same meaning : No scheduled maintenance - means run to fail Scheduled discard and restoration - Preventive Maintenance On-Condition Tasks - Means Condition-Based Maintenance also with the inclusion of using human senses to detect potential failures. By the way, have you completed writing your book ? And is it already out in the market ? My Warm Regards, |
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Rolly,
I am not sure if I am acting within the rules of the forum while answering your question. At the risk of getting a slap on the wrist, here goes: My second book written with M.C.Das and J.Wardhaugh "100 Years of Maintenance: Practical Lessons from Three Lifetimes" # ISBN-10: 0831133236 and # ISBN-13: 978-0831133238 was completed about 4 weeks ago and is due for release in the next few weeks. You can see details on the Industrial Press or Amazon websites. I am happy to tell you that it has a Foreword by Charles Latino,one of our Reliability Greats and a Guru, and reviews by Brad Peterson, President of the SAMI Corporation and Joel Leonard, the Maintenance Evangelist. Regards, V.Narayan (Vee) Lead Author, 100 Years of Maintenance: Practical Lessons from Three Lifetimes, Industrial Press.NY ISBN-13: 978-0831133238 Author, Effective Maintenance Management: Risk and Reliability Strategies for Optimizing Performance, 2004, Industrial Press NY ISBN-13: 978-0831131784 |
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We welcome any news about your new book Vee!
It will be proudly displayed at IMC-2007. Terry O |
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From the Reliability Centered Maintenance Project Manager’s Guide (PDF)
To avoid confusion between terms and phrases used in other contexts within the fields of Maintenance and Reliability (M & R) the following notes are provided. Note 1: Corrective maintenance in the context of the metrics included in the RCM Scorecard refers to unplanned (unexpected or reactive) maintenance to restore the functional capabilities of an asset. It includes repeat maintenance required because initial attempt(s) at repair were not successful for any reason. It does not include maintenance that results from preventive or predictive (PM and on condition or condition directed, or PdM) tasks, which can be anticipated, pre-planned and scheduled. Corrective maintenance is a subset of Emergency/Demand Maintenance. Note 2: Corrective maintenance in the Total Productive Maintenance (TPM) sense refers to actions taken to modify the asset to improve its performance. The labor hours and material costs for these improvements (as well as those that improve asset maintainability) should be categorized separately and not be included as part of any metric associated with the RCM Scorecard, unless the recommendation of a design improvement results from RCM analysis on an asset. |
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Hello Vee,
Congratulations on your new book. Hope I can purchase it directly from you, someday maybe early dec or end nov. 2007. Highly appreciate some signature and brief note on your book. I'll email you personally regarding this matter. I know this is not the venue for promoting. Charles Latino is a very reputable and respectable person when it comes to reliability and root cause. I learned from Bob Nelms that he (Charles) was his boss way way back ago. In behalf of the people from the far east, your continuous contribution to reliability and risk management is highly appreciated. My Warm Regards, |
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We should use generic terms like planned prevetive maintenance, corrective maintenance, plant change, non-core maintenance jobs.
All activities resulted from maintenance strategy, RCM, TPM, IPF, RBI etc are planned maintenance. This message has been edited. Last edited by: Josh, |
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On 11/01/2007 Maintenance Tips published the following:
Preventive Maintenance (PM) Tip Is it Preventive Maintenance (PM) or Corrective Maintenance (CM)? A dominant area of confusion about Preventive Maintenance (PM) versus Corrective Maintenance (CM) occurs when a scheduled task reveals unacceptable equipment deterioration. So actions are taken to repair/restore the full functionality before an unexpected operational impact can occur. Is the repair/restore action preventive or corrective? If the purpose of the PM task is to perform actions that will retain functional capabilities, then the answer is essentially self evident — the repair/restore action is preventive. Why? Because a proper structuring of the PM task will always include not only the search for equipment condition, but also the requirement to do something about it if the search uncovers a problem. This search includes PM tasks that require inspection, monitoring parameters that detect failure onset, discovery of hidden failures and even restoration of equipment that was deliberately allowed to run to failure. Unfortunately, though, many CMMS programs will not allow the user to create or code a new work order to cover the emergent work as PM. This additional PM work can only be coded as CM. This inflates the cost of CM, and can lead management to question why CM costs are increasing even when their PM program had been recently improved. Tip provided by Anthony "Mac" Smith, Author, RCM - Gateway to World Class Maintenance, Butterworth-Heinemann, ISBN-10: 075067461X |
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ON 11/06/2007 we got this feedback about the Tip published in 11/01:
I would like to comment on Mr. Smiths earlier Preventive Maintenance (PM) Tip Is it Preventive Maintenance (PM) or Corrective Maintenance (CM)? In the tip he makes the point that items found during the preventative maintenance are also preventative maintenance and should be coded as such. If not then the question comes why are you finding so much corrective maintenance. I disagree with this. Preventative maintenance is the closet thing to standard work that the maintenance department has. With this type of work the cost and time to perform should be constant each time the work is performed. Otherwise how do you schedule. Yes an adequate PM is designed to find the deficiencies prior to failure and can be part of an effective program but the repairs to the equipment should be corrective (CM). If not then my question is why are your PM costs so out of control. Most CMMS programs allow you to create your own coding system. I have created and used the PM-Repair code to show what we have found and fixed using the PM program. This along with PM costs and CM costs will show an effective program. The curve will show as PM costs go up the PM-Repair costs will peak and then decrease and the CM costs will decrease. The point at which the PM costs, PM-repairs and CM costs are at the minimum is the maximum you are going to get from the current PM program you are using. At that time only a change in the maintenance will cause a continual decrease. Feedback provided by Clint Mileur Maintenance Manager JamesHardie Building Products Peru IL |
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Yes, to repair major defects found during PM will inflate the PM cost but not the minor defects. Therefore, the PM doers should decide whether to repair the defects straight away using the same PM work order, same work permit, same person, etc, or to rectify the defect later on using a corrective/preventive maintenance work order and another work permit etc.
Perhaps, as a rule of thumb, it's alright to rectify defects immediately if can be completed within 1 or 2 hours e.g. cleanliness, looseness, etc. Just add a small operations under the same work order in the CMMS to notify it has been done. But if the defect requires an overhaul after condition monitoring as an example, then a separate child work order should be raised. Under Equipment basic care, I thought we encourage the problem finders to rectify the problems found right away, if possible instead waiting for or passing to another persons. |
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