You select and apply maintenance strategy with the purpose of controlling failure. Your maintenance management starts on the project drawing board. If you only select your maintenance management strategies when the equipment is installed, you will always be fighting a losing battle!
Abstract:Equipment Maintenance Management Strategy 101. Maintenance is a risk management practice used to maximise production and minimise loss and waste. Selecting a successful maintenance strategy requires a good knowledge of equipment failure behaviour and maintenance management practices. Once you appreciate why equipment fails, how equipment fails and when equipment fails you can select the right mix of maintenance strategies to extend and maximise its service and performance.This article takes you through the factors which affect equipment performance and service life. It also introduces you to the maintenance strategies available to you today and how they work. You will also discover within the article many maintenance management benefits that each maintenance strategy will bring you.
Keyword: Equipment maintenance strategy, maintenance strategies, maintenance management strategy benefits, strategic maintenance planning, equipment maintenance policy
To master a thing you must know it thoroughly. When you speak to experts it is clear that they are intimate and absorbed with their speciality. When you understand a thing fully, when you know how it will behave under all circumstances, when you introduce a change and know its impact and effect, then you have mastery over the thing.
So it is with maintenance strategy. Strategic maintenance decision making involves selecting the right care and repair methodologies that maximise equipment life and performance for the least cost to the user. But to be able to make successful maintenance management strategy choices you must understand how equipment fails. When you know the equipment’s weaknesses and strengths you can care for it properly and get maximum service from it at least cost.
How Equipment Fails
Today’s equipment technologies can be broadly grouped as mechanical or electrical. Equipment in both groups has physical presence. You can touch them. Because they are made of solid matter they can break or deteriorate.
Equipment fails because its physical substance and structure cannot support the last duty required of it. In other words a final incident destroys it because it is not physically able to withstand that incident. In some cases the end of an equipment’s life is instantaneous and without warning. Many times there is a gradual worsening of performance that can be detected.
Why Equipment Fails
You already know that anything solid can be broken or will deteriorate. Equipment fails because some part of it has broken or deteriorated. The question we need to ask is – “What can cause an equipment part to break or deteriorate?” There are usually hundreds of combinations of causes that can make a piece of equipment fail. Fortunately they can be categorised into a few simple explanations.
Physical matter can only survive within a limited range of imposed stresses and environments. Once matter is stressed beyond its endurance it will suddenly fail.
Some common examples are overloading, becoming too hot and placing an item under fluctuating forces leading to fatigue situations.
This is the case where the environment around the equipment actually damages the equipment. When environmental attack gets too severe the equipment is compromised and fails, as it no longer has the strength or capacity to handle its duty.
Common examples are rusting, chemical corrosion, wear, erosion and cavitation.
Error or Mistake
Equipment can fail due to the wrong thing being done to it, or a wrong choice being made in ignorance. Failure by error can start on the drawing board at the design stage. It can be due to an operator or maintainer making a mistake. It can be due to incompetent management decision.
Some examples include starting equipment when not fully rebuilt, forgetting to put oil in a gearbox, introducing incompatible chemicals and doing the wrong instruction sequence.
Poor Design Choices and-or Poor Manufacturing / Assembly Quality
As the heading implies there are times when a part is made incorrectly, built incorrectly or its design was unable to withstand the imposed service duty.
Design errors include selecting undersized equipment, wrongly specified components and introducing safety risks. Manufacturing errors like poor welding, poor casting, incorrectly positioned holes and out of tolerance machining are real possibilities. Similarly, assembly errors, such as under-torque on bolts, poorly fitted electrical connections and short-cut assembly quality practices will eventually lead to equipment failure.
Lack of Maintenance and Care
When equipment is designed the designer makes the assumption that it will be treated with reasonable care and it will undergo a minimum amount of required maintenance. When care and maintenance is withheld from equipment for an extended period of time, accumulated problems develop which eventually cause failure.
This can include not changing lubricating oil, leaving electrical equipment open to dust and dirt ingress, starting machines under full load, not checking remaining service life and not cleaning equipment down.
Unimagined Incidents and Knock-on Effects
Occasionally an unexpected disastrous event occurs that destroys equipment. These include sabotage, acts of God, such as lightning and terrorism.
Included in this category are unforseen preventable events that are a consequence of planned events. An example is where a bolt falls into a machine during a repair and is not noticed. On start-up the bolt is jammed into the working parts and causes a breakdown. Another example is negligent behaviour, such as backing forklifts into operating plant or out-of-control vehicles running into machinery.
When Equipment Fails
Equipment failure is defined as the point when the equipment no longer delivers the minimum duty required of it. It may not yet be broken, but it is not able to deliver the needed service.
The actual time of failure depends on when the cause of the failure coincides with the item’s ability to accommodate the failure mechanism. This means that the failure happens at the time the item can no longer operate as required. This point in time can be controlled by the selection of the right maintenance strategies!
Equipment failure can even be totally prevented with appropriate maintenance strategy.
Available Maintenance Strategies
There are several maintenance strategies available. They range from pre-emptive methods that remove the need for maintenance. There are those that cover the ways to maintain well and on to failure analysis methods for removing existing failures.
Pre-emptive Detection and Elimination
Strategic maintenance planning should start on the drawing board. Once an item of plant is built you are stuck with it! A piece of equipment requires what maintenance it needs to maintain its performance. There is no escaping the fact that the design specifies the maintenance requirements. Unless the necessary maintenance is done it will fail!
If you want less maintenance, you must start with appropriate design choices that reduce the amount of maintenance. The methods used to highlight opportunities to reduce maintenance are based on failure mode and effects analysis (FMEA). A simple way to understand the approach is to consider it as a series of answers to ‘what-if’ questions used on each part of the equipment.
For example, ‘what-if’ the shaft bearing lost lubrication? The bearing would run dry, heat up and start wearing out. To prevent such a failure we need to provide maintenance that ensures the bearing is regularly lubricated. A further example might be ‘what-if’ there was loss of power? Should it happen what would be the effects? Depending on the consequence of the effects you would put into place suitable design features to reduce the impact of the failure.
Pre-emptive maintenance strategies are the best because they are the least expensive way to reduce maintenance! Their beauty and wonder is that they are an equipment lifetime strategy that brings continual better operation for the equipment’s entire operating life.
The results of using a Pre-emptive Detection and Elimination maintenance strategy will flow through to you immediately, but not be seen for a year or two. You will start noticing that the regularity of failures usually expected from such equipment is not happening.
Quality Control and Assurance
This strategy originated in the manufacturing industries and applies equally to maintenance work. It is simply the proper and correct control of manufacture and assembly so that equipment is built precisely as it was designed, with correct and accurate components. It involves substantiating and proving that each equipment item meets its design requirements and that it is assembled into the equipment correctly.
Typically this involves following specified, written procedures on how the work is done. It includes test and check steps to confirm compliance and documented proof that the procedure was followed.
When equipment is accurately and properly assembled using the right parts, it lasts longer between repairs and so has a longer mean time between failures (MTBF). It also runs sweeter and produces more consistent output.
Adopting a Quality Control and Assurance maintenance strategy improves the quality and accuracy of parts and workmanship. This translates into better running equipment with longer mean times between failures. This strategic maintenance move will produce results immediately though stopping mistakes. You will see the benefits in six to twelve months time.
Preventative Maintenance (PM) strategy was one of the very first and it is still very effective. It comes in two forms – 1) inspection and observation and 2) intervention and replacement.
The first Preventative Maintenance form is the usual response used for equipment and parts that show signs of age and wear-out. It involves inspecting and noting the condition of equipment and its parts and servicing it on a regular basis, such as changing old lubricant.
While the servicing is done it is an ideal time to look for evidence of impending failures in critical and working parts. If failure evidence is found, the part is changed for new immediately or at the earliest convenient time before breakage.
A Preventative Maintenance strategy stops failures with the very first use. You can expect a well run and always done-on-time PM strategy to stop failures by up to 90%. You will not greatly reduce the amount of maintenance; only stop most of the breakdown failures. Its benefits will be seen in the first month or two.
Shutdown Overhaul Maintenance
The second PM form is to automatically replace the parts known to experience age and use related degradation on a set frequency shorter than the mean time between failures. Doing this should prevent an unexpected failure and give maximum production time.
Such work is typically done as an overhaul where the whole of the equipment is removed from operation during a shutdown and taken to the workshop to be stripped down to its component parts and rebuilt as new.
Use of Shutdown Overhaul maintenance strategy is aimed at ensuring uninterrupted production for a specific period of time. By renewing equipment regularly you remove the wear-out related stoppages. Once equipment is overhauled to manufacturer’s standards you can expect as-new performance. However you are also exposed to ‘infant mortality’ risks due to poor quality control, mistakes during assembly, incorrect material selection and introduced damage.
You would do best, if you use a Shutdown Maintenance Strategy, to use a sound and robust Quality Control and Assurance Strategy with very good rebuild and checking procedures.
Predictive Maintenance (PdM) is a very powerful maintenance strategy. It involves monitoring for evidence of changed conditions within the equipment. The amount of change and the rate of change are tracked and used to predict the time of failure.
PdM is based on the recognition that many failures take time to happen. Typically there is a start point, a gradual worsening, and eventually a point where the item cannot perform its duty. Finally there is a point in time when it breaks and totally fails.
If it is possible to detect early onset of the failure then there is often time to manage the equipment carefully and continue operation until a replacement is actually needed.
PdM techniques include thermography, oil debris analysis, vibration monitoring and ultrasonic thickness testing. They are all methods that detect a change, and allow measurement of the rate of change, so that predictions can be made on the equipment’s continuing performance.
When you use a predictive maintenance management strategy you will spot problems immediately and can act on them before a failure occurs that shuts the operation down.
Intentional Over-Design Selection
There are times when it is useful to select more robust equipment than superficially appears necessary. This is a strategic maintenance choice that is intended to produce longer periods of equipment operation between failures.
It involves specifying equipment with stronger, harder, more resistant parts, using longer lasting components, applying improved protection against ingress of the external environment and the like.
There maybe a higher purchase cost but it is offset with more production output over the equipment life. You will get immediate benefits through fewer stoppages and will see its worth in the first year or two.
New inventions and innovative designs usually occur in response to existing problems. It is a wise and valid maintenance strategy to be constantly looking for new technologies that reduce equipment operating problems.
When a potentially useful technology is found test it in a controlled and monitored experiment to prove its worth in your situation.
It is my strong belief, after decades of involvement in maintenance management, that the only long-term solution to the need for maintenance it to invent equipment that does not need it. This means discovering new technologies that do not fail, or that vastly increase the mean time between failures.
Actively look for such technologies because they will make your operation wealthy. Make it an engineer’s task to spend time each month seeking improved technology that stop the need to do maintenance or that boosts reliability.
When you change to a new technology that solves a maintenance problem you immediately gain the benefit of improved production output. This benefit continues throughout the equipment’s life.
Root Cause Elimination and Design-Out
You need a maintenance strategy that solves your problems and continually improves your plant and equipment performance! This is a strategic maintenance step, that if not done, results in long-term deterioration in production plant performance. If operating problems are not removed by designing them out, then the problems will accumulate to the point where production falls because equipment continually fails.
A problem can only be prevented from reoccurring if it is eliminated. There are methodologies available that use a systematic approach to trace the real cause of problems to their root cause. By removing the root cause the problem can then not reoccur and you have improved your operating performance!
The benefits of root cause elimination are immediate with the permanent removal of a failure cause. The problem disappears for the rest of the equipment’s life.
Proactive Education and Training
People can only change their behaviour and thoughts when they find better ways to behave and think. Once a person knows what is right to do, they will most likely do it.
Ignorance is hugely expensive! One of the best maintenance strategies is to teach the engineering design requirements of the equipment to the operators and maintainers who will run and care for it. This is a sound strategic step because it means key knowledge is transferred to the users of the machinery.
Knowledgeable users will make wise choices and take correct actions. The wise and knowledgeable operation and care of plant and equipment translates into longer periods of trouble-free operation and increased throughput.
A proactive training program involves 10 working days a year per employee of technical, safety and engineering training on the design and operation of the equipment and systems used in your operation. Included in the training is regular introduction to new information and constant revision and reinforcement of the key factors that produce long and reliable operation of your equipment.
Training and education benefits your future. Continuous improvement requires continual learning. Train your people well and they will bring benefits to the operation within six months. Most importantly they will think of new ideas and bring innovations into the business which produces competitive advantages.
Maintenance Planning and Scheduling
This is a key strategic maintenance planning move! It is based on the principle that prior planning and preparation will improve the actual performance and execution. It is why elite athletes do not compete unless they have trained for the event. They know that unless they have prepared thoroughly beforehand they will not succeed!
It is exactly the same with operations and maintenance – each must be thoroughly planned and organised before being done.
If you do not yet do maintenance planning and scheduling and you introduce it, provided you do it well, you can expect to reduce your maintenance crew manning by at least 25% over the next two years time. You will start seeing manpower efficiency improvement within six months. Another certainty is that it you use a planning and scheduling system to insure the preventative maintenance is done on time, you will see a reduction in breakdowns within three months.
Getting the Right Mix of Strategic Maintenance Management Strategies
There is no one maintenance strategy for all situations and all companies! Rather you require a blend of maintenance management strategies that are right for your operation and for the age of the equipment.
You will always require an amount of preventative maintenance, as well as an amount of predictive maintenance when equipment ages, along with root cause analysis to elimnate non-random failures. To this is added appropriate training, occasional overhaul shutdowns, replacement of old technologies with new, and so on.
The choice of the appropriate maintenance strategies is what strategic maintenance planning is all about. Strategic maintenance planning should also recognise when it is necessary to change the maintenance strategy mix.
To help you discover the right maintenance and operating strategies to match equipment life cycles, click on this link and read the article titled Equipment Reliability 101.
Further Strategic Maintenance Planning Assistance
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