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| An Effective Maintenance Strategy |
| by John van den Hoek and Richard Beer |
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| Maintenance exists to protect your plant's physical assets. An effective maintenance strategy ensures that you get the maximum life from your building, utilities and production equipment for the most economical cost. Maintenance does this by managing the aging process, for at some point in time, all equipment will fail. Maintenance manages the aging process by: |
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monitoring the equipment conditions, |
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making adjustments, |
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lubricating equipment, |
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repairing damage due to external forces such as: |
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wind damage, |
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forklift-truck impact, |
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machine crashes due to limit switch failure, etc. |
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It replaces worn and failed parts. |
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| Your maintenance strategy can keep your plant's equipment functional however, maintenance does not extend the design life. In order to do that, overhauls and rebuilds become necessary and are normally over and above what maintenance does. It is then considered a capital expense. |
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| Would you always overhaul your existing equipment? Will the refurbished machine function as well as a new machine? Keep in mind that rebuilding will probably cost at least 50% the cost of a new machine, if not more. In some instances, such as re-tubing a boiler, or turbine re-blading, it does make sense. The effect maintenance has on a facility's bottom line must be considered. |
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| Maintenance has evolved into at least 5 distinct programs of ever increasing complexity. They range from allowing equipment to run until it fails, to trying to prevent every possible failure. Each of these programs has its place in the overall maintenance strategy. These five programs have generally been labeled as: |
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- Breakdown,
- Planned Preventative Maintenance,
- Predictive Maintenance,
- Reliability Centered Maintenance, and
- Total Productive Maintenance.
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Breakdown Maintenance
Breakdown maintenance works on the premise of if it ain't broke, don't fix it. |
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| Example: Automotive lights are a prime example of a part of your car that you would run to failure. You simply replace the bulb when it is burnt out, an easy simple fix with no adverse effect on your vehicle. However, if you run your brakes to failure, it becomes very costly to repair or replace. Using break down maintenance, you allow the brake linings to wear out, scoring your rotors, and ultimately heating a wall because you cannot stop, never mind the safety hazard you are creating. Anyone who has experienced this knows that's not very cost effective. |
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| In the past, the results of a failure were not perceived as avoidable or serious. As a consequence, maintenance was viewed as a necessary evil. The only maintenance functions performed with a break down maintenance plan are those of a routine nature such as lubrication, tightening of loose bolts, and watching for signs of trouble. Repairs take place when a machine has worn to the point that the machine's performance is intolerably poor or an actual break down has occurred. In effect, the machine controls the maintenance cycle. |
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| Machines allowed to run to failure require more extensive and expensive repairs. There are several reasons for this: |
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Failures always happen at the most inopportune time such as in the middle of a critical production run, and as a result |
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Repairs are rushed by production managers. |
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Little can be done beforehand such as allocating manpower, tools, and replacement parts. |
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| There is no reason to expect that breakdowns will limit themselves to the capabilities of the plant's workforce. A maintenance staff of any size and collection of skills will almost always be feast or famine. |
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| Some failures can be catastrophic and may require the replacement of the entire machine. Again, added costs of this approach can include |
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the direct costs of the repairs, |
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investigative costs to determine the root cause, or expect repeat lost production |
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production scrap or production marginally on specification that gets shipped to the customer who may complain about declining quality.
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