In most industries, maintenance and operations hold meetings everyday to discuss what had failed, and sometimes what is done to stop it from happening. In Proactive Maintenance, it is likely to identify all failure modes which are likely to affect the asset in order to determine what will happen when a failure occurs and what should be done to anticipate prevention, detection, prediction or redesigning the equipment.
Proactive Maintenance is about analyzing why failures occur so that recurrence is finally eliminated and thereby extending the life of the part or component of a machine. Proactive Maintenance is when maintenance team or a group of cross functional team analyzes the failure with analytical techniques such as Root Cause Failure Analysis, FMEA, Kepner Tregoe, Why-why Analysis, P-M Analysis, Fault tree Analysis, etc. are used to better understand why the failure occurred in the first place.
Remember that in Preventive Maintenance, we replace the part that we think is in the process of wearing out. In this type of maintenance task, we think that replacing the part will bring the equipment back to its original condition. But we have not taken into account the need to analyze further why a certain part keeps on failing.
In Proactive Maintenance, we need to understand the following concepts:
1.Redesign or modification. Includes changing the specification of the component, adding a new item, replacing an entire machine with a different type, relocating a machine or changing the process or procedure which affects the operation of the machine
2.Safety and Environmental Aspects. Reduce the probability of failure mode occurring to a level which is acceptable, replacing a component with stronger or more reliable replacement making the failure no longer a threat to safety and environment.
3.Operational and non-operation consequences. Reduce the number of times failure occurs, reduce or eliminate the consequences of a failure (example thru redundancy) and preventive tasks is cost effective hence alternate solution is to re-design.
Before a machine is to be re-designed, we must first understand several factors to be considered. First, the failure must have involved a major operational consequence. Second, the cost of the scheduled maintenance or breakdown maintenance must be high. Third, the specific cost which can be eliminated by the design change is notable. Forth, the design should have no harmful effects which can be generated afterwards. Fifth, there should be an economic trade off study on expected cost savings when re-design is made. And lastly, the asset to stay or to be used for a long time and not will be decommissioned.
Trouble shooting as in the case of Reactive Maintenance is no longer an effective strategy. In today’s competitive works, the “Analysis” finds the real solutions. And thus, Proactive Maintenance is a must!.
Friday, June 26, 2009
Understanding the basic concept of manufacturing equipment Predictive Maintenance
Predictive Maintenance aims in detecting potential failures in equipment with the aid of specialized instruments. Maintenance is based on the condition of the equipment which differentiates it from Preventive Maintenance.
To further illustrate the meaning of Predictive Maintenance, a person is gifted with five senses (touch, smell, taste, hear and sight). He can use these senses to detect problems on the equipment. Predictive Maintenance is also called Condition-based monitoring which checks the condition of equipment through the use of sophisticated measuring instruments with precision accuracy. Therefore Predictive Maintenance instruments are a higher form of human senses.
In Predictive Maintenance, it takes into consideration the actual condition of the equipment when deciding whether maintenance is necessary. It requires a regular monitoring of critical equipment and predicts problems before they occur. Therefore, since all failures can be predicted, the user can establish a prognosis for the fault. The most important information here is to determine how rapidly the fault or failure is progressing, when it is likely to stop the machine from fulfilling its design function and what are the consequences of the failure itself.
According to Mirriam Webster Collegiate Dictionary, Predictive means to declare or indicate in advance, especially foretell on the basis of observation, experience or scientific reason. It is from Latin word pre (before) and dictionm also from Latin word dicare (to proclaim).
Predictive Maintenance is a maintenance activity geared to indicating where a piece of equipment is on the critical wear curve and predicting its useful life. This is done with the aid of specilized diagnostic instruments. Predictive Maintenance aids us in determining the potential failure or symptoms that an equipment is in the process of failing. Changes or increase in the following can denote a potential failure.
Specialized diagnostic instruments can aid in detecting the following :
1.Changes in the heat or temperature of the equipment
2.Vibration of machines over time
3.For machine’s electrical system, we have changes in resistance, changes in conductivity and changes in dielectric strength
4.Increase in equipment’s noise
5.Change in the pressure input or output
6.Change in the machine’s flow rate
7.Lubricant contamination
8.Wall thickness decrement
9.Rate of corrosion
10.Leak detection
11.Crack detection
Our goal in maintenance is to keep our physical assets in an existing estate. Prediction is a declaration in advance that something is going to happen and from the dictionary, Predictive Maintenance is a proclamation or declaration in advance based on observation to preserve (something) from failure or sustain it against danger.
To further illustrate the meaning of Predictive Maintenance, a person is gifted with five senses (touch, smell, taste, hear and sight). He can use these senses to detect problems on the equipment. Predictive Maintenance is also called Condition-based monitoring which checks the condition of equipment through the use of sophisticated measuring instruments with precision accuracy. Therefore Predictive Maintenance instruments are a higher form of human senses.
In Predictive Maintenance, it takes into consideration the actual condition of the equipment when deciding whether maintenance is necessary. It requires a regular monitoring of critical equipment and predicts problems before they occur. Therefore, since all failures can be predicted, the user can establish a prognosis for the fault. The most important information here is to determine how rapidly the fault or failure is progressing, when it is likely to stop the machine from fulfilling its design function and what are the consequences of the failure itself.
According to Mirriam Webster Collegiate Dictionary, Predictive means to declare or indicate in advance, especially foretell on the basis of observation, experience or scientific reason. It is from Latin word pre (before) and dictionm also from Latin word dicare (to proclaim).
Predictive Maintenance is a maintenance activity geared to indicating where a piece of equipment is on the critical wear curve and predicting its useful life. This is done with the aid of specilized diagnostic instruments. Predictive Maintenance aids us in determining the potential failure or symptoms that an equipment is in the process of failing. Changes or increase in the following can denote a potential failure.
Specialized diagnostic instruments can aid in detecting the following :
1.Changes in the heat or temperature of the equipment
2.Vibration of machines over time
3.For machine’s electrical system, we have changes in resistance, changes in conductivity and changes in dielectric strength
4.Increase in equipment’s noise
5.Change in the pressure input or output
6.Change in the machine’s flow rate
7.Lubricant contamination
8.Wall thickness decrement
9.Rate of corrosion
10.Leak detection
11.Crack detection
Our goal in maintenance is to keep our physical assets in an existing estate. Prediction is a declaration in advance that something is going to happen and from the dictionary, Predictive Maintenance is a proclamation or declaration in advance based on observation to preserve (something) from failure or sustain it against danger.
Understanding the Basic Concept of Manufacturing Equipment Preventive Maintenance
Preventive maintenance is also known as Time-based or Calendar based maintenance. Maintenance activities are performed on a calendar or fix operating schedule in order to extend the life of the equipment and prevent failures. In preventive maintenance, maintenance is performed without regard to equipment condition. It assumes that the condition of the machine and the need for maintenance is correlated with time which means that the item can be expected to operate reliably for an amount of time and is expected to wear out. A failure rate and history records are used to established the best frequency. Therefore, a preventive maintenance is simply performing maintenance on a fixed interval which may in the form of time, number of strokes or frequency.
Stress can cause an asset to deteriorate by lowering its resistance, exposure to stress includes output, distance traveled, operating cyscles, calendar time and running time. When the part or component wears out directly with respect to its operating age, these parts will survive this defined age (example, 98% of impelers were replaced after the end of 2 years). The part or component will have a normal rate of wear, TPM term will be normal fatigue. Fatigue happens when stress exceeds the strength of the material of the spare part or component. Application of Preventive Maintenance task will only be worth doing and feasible to parts that will have a normal wear or deterioration.
Preventive maintenance will include regular checking, cleaning and inspecting, scheduled parts replacement and controlling, regular routine lubrication, regular calibration, periodic preventive maintenance schedule and monitoring activities. Replacement of parts or overhauls is either based on time-dominated frequency number of strokes or running hours. There is a high probability of failure at the end of the period and failure will survive up to this point, then Preventive Maintenance is worth doing.
But, preventive maintenance is limited when founded on the belief that a given history of failures of a given components failing after a certain number of hours used or other measurements. But most parts based on the averages. Preventive Maintenance carry out the maintenance work at regular intervals, problems with this practice is that since most tasks are based on the average maintenance may carry out work that is not required and probability of replacing parts which are still in working conditions. Since this is a Time-based Maintenance, studies have shown that most of equipment failures are not related to the number of hours.
Stress can cause an asset to deteriorate by lowering its resistance, exposure to stress includes output, distance traveled, operating cyscles, calendar time and running time. When the part or component wears out directly with respect to its operating age, these parts will survive this defined age (example, 98% of impelers were replaced after the end of 2 years). The part or component will have a normal rate of wear, TPM term will be normal fatigue. Fatigue happens when stress exceeds the strength of the material of the spare part or component. Application of Preventive Maintenance task will only be worth doing and feasible to parts that will have a normal wear or deterioration.
Preventive maintenance will include regular checking, cleaning and inspecting, scheduled parts replacement and controlling, regular routine lubrication, regular calibration, periodic preventive maintenance schedule and monitoring activities. Replacement of parts or overhauls is either based on time-dominated frequency number of strokes or running hours. There is a high probability of failure at the end of the period and failure will survive up to this point, then Preventive Maintenance is worth doing.
But, preventive maintenance is limited when founded on the belief that a given history of failures of a given components failing after a certain number of hours used or other measurements. But most parts based on the averages. Preventive Maintenance carry out the maintenance work at regular intervals, problems with this practice is that since most tasks are based on the average maintenance may carry out work that is not required and probability of replacing parts which are still in working conditions. Since this is a Time-based Maintenance, studies have shown that most of equipment failures are not related to the number of hours.
Understanding the basic concept of manufacturing equipment Reactive Maintenance
Reactive Maintenance is done at a point when there is a repair or actual breakdown. It occurs when repair action is taken on a problem only when the problem results in machine’s failure. Unplanned downtime, in it’s simplest definition, breakdown maintenance simply means fixing when it fails. It is a strategy which tells us that when a machine fails, then it is time for maintenance to fix it. Limitations of breakdowns maintenance is that it is cause unplanned downtime and production delays which results in revenue losses and extending the maintenance of work overtime to fix the equipment. Repairing the equipment after it fails usually creates the possibility of secondary damage which increase the maintenance cost. Allowing failures to occur can be applied to the asset if the consequences of failure and the cost of repair is minimal and acceptable to both the user and maintenance.
The common mind set of maintenance personnel is that “if isn’t broke, don’t fix it. And when it breaks, will fix it”. When this is the sole type of maintenance practice, then the consequences involves the high percentage of unplanned activities, high replacement and parts inventories and high pressure to keep the equipment running. A pure reactive maintenance strategy ignores opportunities to influence equipment reliability and survivability. A justifiable instance includes if it does not produce critical delays, it does not sacrifice people’s safety and it does not significantly increase costs.
In Reactive Maintenance, we must consider the following:
1.“Run to fail” is valid if a failure is evident and does not affect safety or environment, or if it is hidden but does not affect safety or environment, then default decision is “not scheduled maintenance”. Run to fail maintenance is valid if suitable scheduled tasks cannot be found for hidden function. And a cost effective preventive task cannot be found for failures which have operational or non-operation consequences.
2.“Redundancy or standby”. Duplicating the system or component failures are allowed or being tolerated through redundant or duplicated functions.
3.“Alternative means”. The presence of redundancy or alternative means of production is a feature of the operating context which must be considered in detail when defining the functions of these assets in its present operating context. Often times termed as standby- unit, even with the same equipment type, standby-units have different degree of maintenance requirements as the duty unit and most failures for standby unit are hidden. To set an example, in civil aviation, a high number of items classified in the redundancy level allowing failure to happen. When the aircraft is in the air, back-ups are use just in case failure is experience when the plane is in motion. Since safety is the priority, failures are then allowed to happen.
In assessing a Reactive Maintenance task, the assessor should be guided accordingly; if the monitoring, scheduled maintenance or inspection required for safety or environmental compliance; if the breakdown will be more costly than the task or preventing the failure itself; if the equipment in the critical path in manufacturing or considered a bottleneck equipment or process; if the back-up equipment is not available; if the breakdown adversely affects delivery or customer service or provide any delays; and lastly, if the breakdown further damage the equipment or provide secondary damages. Then Reactive Maintenance is justified.
The common mind set of maintenance personnel is that “if isn’t broke, don’t fix it. And when it breaks, will fix it”. When this is the sole type of maintenance practice, then the consequences involves the high percentage of unplanned activities, high replacement and parts inventories and high pressure to keep the equipment running. A pure reactive maintenance strategy ignores opportunities to influence equipment reliability and survivability. A justifiable instance includes if it does not produce critical delays, it does not sacrifice people’s safety and it does not significantly increase costs.
In Reactive Maintenance, we must consider the following:
1.“Run to fail” is valid if a failure is evident and does not affect safety or environment, or if it is hidden but does not affect safety or environment, then default decision is “not scheduled maintenance”. Run to fail maintenance is valid if suitable scheduled tasks cannot be found for hidden function. And a cost effective preventive task cannot be found for failures which have operational or non-operation consequences.
2.“Redundancy or standby”. Duplicating the system or component failures are allowed or being tolerated through redundant or duplicated functions.
3.“Alternative means”. The presence of redundancy or alternative means of production is a feature of the operating context which must be considered in detail when defining the functions of these assets in its present operating context. Often times termed as standby- unit, even with the same equipment type, standby-units have different degree of maintenance requirements as the duty unit and most failures for standby unit are hidden. To set an example, in civil aviation, a high number of items classified in the redundancy level allowing failure to happen. When the aircraft is in the air, back-ups are use just in case failure is experience when the plane is in motion. Since safety is the priority, failures are then allowed to happen.
In assessing a Reactive Maintenance task, the assessor should be guided accordingly; if the monitoring, scheduled maintenance or inspection required for safety or environmental compliance; if the breakdown will be more costly than the task or preventing the failure itself; if the equipment in the critical path in manufacturing or considered a bottleneck equipment or process; if the back-up equipment is not available; if the breakdown adversely affects delivery or customer service or provide any delays; and lastly, if the breakdown further damage the equipment or provide secondary damages. Then Reactive Maintenance is justified.
Principles of Manufacturing Equipment Reliability Improvement
Reliability means the probability that no failure will occur throughout a prescribe operating period.
In the implementation of a improvement programs with respect to any manufacturing equipment, the following tips must be considered:
1.Focus must be on reliability and not cost, because if reliability starts to improve the cost will definitely go down and it cannot be the other way around. There will be times that focusing on cost will hurt reliability, a lesson that we all should reflect upon.
2.Never accepts failures in your plant. Trouble shooting and repair is not longer an effective strategy. In today’s competitive world of manufacturing, the analyst should find real solutions to our equipment problems. Always remember that when our people become really good at repairing failures then something is wrong, since we are doing it much too often, but when we expect a different result from the same things that we are doing. It just isn’t possible, the Chinese called this insanity.
3.The best time to address a problem is when it is small; it’s very hard to advance to a specialized maintenance activities and improvement efforts if equipment’s basic condition had not been established. We should always remember our equipments is a shared responsibility for both operators and maintenance people, a lesson we must all learn from the Japanese. This is the main essence of the TPM (Total Productive Maintenance).
4.In a reactive environment, we always complain that we lack manpower resources to address equipment failures. But when equipments starts to improve, our people are now visible and always wonder where they had been in the first place.
5.The real challenge in any Equipment Reliability Initiative is starting to improve in a reactive world with the same amount of resources and time. Always remember that all best in class companies started from being reactive themselves.
6.There is no silver bullet program or strategy that can transform a plant’s reliability overnight all will start with basic foundation and that is by “education” and changing the mindset of our people.
7.The best maintenance strategy to adopt is to learn when to use the different maintenance strategy simultaneously with the aid of a Decision Diagram or an Algorithm and that the degree of maintenance requirements should always be based upon the consequences of failure itself.
8.For equipment that fails due to lubrication, there is only one secret, just keep the oil clean. If the oil is kept clean, then there is no reason for it to oxidize and moreover no need to change the oil. Oil should be change not based on the number of hours that has run but by the number of contaminants it has.
9.Reliability is not a program with a end but a culture without an end. It’s the same as any continuous improvement philosophy.
10.The distinction between a true blooded maintenance and a mechanic is a maintenance uses more of his brain than his hand while mechanic uses his hand much of the time. Therefore let us treat our people as maintenance and not as mechanics.
11.The best way to change a culture is to focus on results. Remember what gets measured gets done. If we don’t measure our performance, then we are just another person with an opinion. And often, opinions don’t last!
Always remember that in any Reliability Improvement Initiative, the focus must be on the people. Provide them with skills they need and these skills will be used to improve their equipment. People will improve their machines and it is not the other way around.
In the implementation of a improvement programs with respect to any manufacturing equipment, the following tips must be considered:
1.Focus must be on reliability and not cost, because if reliability starts to improve the cost will definitely go down and it cannot be the other way around. There will be times that focusing on cost will hurt reliability, a lesson that we all should reflect upon.
2.Never accepts failures in your plant. Trouble shooting and repair is not longer an effective strategy. In today’s competitive world of manufacturing, the analyst should find real solutions to our equipment problems. Always remember that when our people become really good at repairing failures then something is wrong, since we are doing it much too often, but when we expect a different result from the same things that we are doing. It just isn’t possible, the Chinese called this insanity.
3.The best time to address a problem is when it is small; it’s very hard to advance to a specialized maintenance activities and improvement efforts if equipment’s basic condition had not been established. We should always remember our equipments is a shared responsibility for both operators and maintenance people, a lesson we must all learn from the Japanese. This is the main essence of the TPM (Total Productive Maintenance).
4.In a reactive environment, we always complain that we lack manpower resources to address equipment failures. But when equipments starts to improve, our people are now visible and always wonder where they had been in the first place.
5.The real challenge in any Equipment Reliability Initiative is starting to improve in a reactive world with the same amount of resources and time. Always remember that all best in class companies started from being reactive themselves.
6.There is no silver bullet program or strategy that can transform a plant’s reliability overnight all will start with basic foundation and that is by “education” and changing the mindset of our people.
7.The best maintenance strategy to adopt is to learn when to use the different maintenance strategy simultaneously with the aid of a Decision Diagram or an Algorithm and that the degree of maintenance requirements should always be based upon the consequences of failure itself.
8.For equipment that fails due to lubrication, there is only one secret, just keep the oil clean. If the oil is kept clean, then there is no reason for it to oxidize and moreover no need to change the oil. Oil should be change not based on the number of hours that has run but by the number of contaminants it has.
9.Reliability is not a program with a end but a culture without an end. It’s the same as any continuous improvement philosophy.
10.The distinction between a true blooded maintenance and a mechanic is a maintenance uses more of his brain than his hand while mechanic uses his hand much of the time. Therefore let us treat our people as maintenance and not as mechanics.
11.The best way to change a culture is to focus on results. Remember what gets measured gets done. If we don’t measure our performance, then we are just another person with an opinion. And often, opinions don’t last!
Always remember that in any Reliability Improvement Initiative, the focus must be on the people. Provide them with skills they need and these skills will be used to improve their equipment. People will improve their machines and it is not the other way around.
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