1. Condition Based Maintenance
UNIT-04
Mr. Anil Kumar Rao, Mechanical Engineering Deptt.
RNTU Bhopal
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2. Principles of CBM
Condition-based maintenance (CBM) is a maintenance strategy that monitors the actual condition of an asset to decide what maintenance needs to be done. CBM dictates that maintenance should only be performed when certain indicators show signs of decreasing performance or upcoming failure.
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3. Condition-Based Maintenance Implementation.
Commitment - The maintenance staff must commit to the process and its new technology. It has to trust the training and technology, while management needs to commit to procuring adequate equipment and training for all staff.
 Participation - To achieve success, 100 percent participation in the CBM program is required from all groups. This expectation must be reinforced by management.
 Holistic approach - This applies to all systems throughout the plant with no exceptions.
 Sustainability - The CBM program, staff and equipment must be maintained over time to reap the long-term benefits. As people come and go from the organization, the proper training and resources need to be available.
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4. Pillars of Condition Monitoring
The condition monitoring also known as Dynamic Predictive Maintenance is composed of several functional aspects on which the maintenance is carried out. However there are four important schematic and functional steps observed in any implementation of condition monitoring activity. These functional aspects are often called four pillars of Condition Monitoring. These are following:
Detection,
Diagnosis,
Prognosis, and
Programme
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5. Detection
This pillar of DPM details when of the developing fault has just arisen. This focuses to answer the following 'When' questions.
When might the fault have started?
When (or how early) is the fault noticed?
When does this fault result in a disaster if left unattended?
Diagnosis
Diagnosis concentrates on knowing 'what' of the origin of the fault so that spares parts can be ordered.
What is origin of the fault?
At what stage is the fault now?
What is the growth rate of the fault?
What are the components or parts that suffering from this fault?
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6. Prognosis
This pinpoints what could happen if the fault is left unattended, i.e. the FORECAST of after effects. Subsequent measurement will then establish the trend to indicate what may happen. This function puts the effort to answer the following queries.
What is the severity of the fault?
What could be the results of the fault?
What could be the production loss?
What is cost of the fault in terms of hours of production and maintenance or repair?
What are the side effects?
What is the trend of the failure? (progressive/constant/retrogressive)
What is the lead time?
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7. Programme
This function is concerned with preparation of SCHEDULE to enable the repair, schedule to be planned. This function attempts to reply the following type of questions:
When should the equipment be taken for maintenance or repair?
What maintenance policy should be adopted?
When should the restoring action start and likely time when it can be finished?
Who will maintain or repair so as to restore the condition?
What is the action plan?
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8. Benefits from condition based maintenance
Safety:
The injury and fatal accidents can possibly be reduced by adopting the safety measures in equipment and system. So, the condition based maintenance enables the system by indicating the future failure in the form of giving signal to the operator.
Extended useful life:
The continuous monitoring enables the system to avoid sudden failures which is not unscheduled. It extends the life of the equipment considerably.
Enhanced availability:
The breakdowns are minimized through proper maintenance which leads to increase the availability. It is achieved by reducing the down time.
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9. Reduction in maintenance time:
The repair time and fault correction time can be reduced by condition based maintenance.
Improved output:
The output of the process is directly linked with the availability, enabled life of the equipment, reduced maintenance time. The condition based maintenance improves these three factors which lead to improve the quality of products.
Quality product:
The better quality products could be ensured through condition based maintenance with healthy equipment in the process line. The quality of the products will satisfy the customer expectation.
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10. Improved reliability
Since the condition monitoring can predict the possible failures, it is possible to remove or replace a piece of equipment before any series consequences arises and hence, the reliability of the equipment can be improved.
Improved planning:
Condition monitoring also helps in improving maintenance and production planning. This is due to the fact that the ability to predict the onset of failure ensures that the organisation of materials and staffing can be carried out in advance, and fitted into any existing schedules. The reduction in unexpected failures should reduce the need to reschedule or cancel the existing work.
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11. Condition Monitoring Techniques
The evolution of information technology has done much for automating condition monitoring and making it practical for a wider rang of users. We would consider traditional techniques, most of which can broadly be classified in following types-
Performance monitoring
Visual monitoring
Vibration monitoring
Temperature monitoring
Lubricant monitoring
Leakage monitoring
Crack monitoring
Corrosion monitoring
Thickness monitoring.
Noise monitoring; etc.
Other monitoring methods, commonly used-
Pressure monitoring
Flow monitoring
Level monitoring
Physical monitoring
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12. Performance monitoring-
Though Performance monitoring is, basically, essential for production, these also help in indicating monitoring of equipments. Primary Performance parameters are-pressure, temperature difference and comparison ratio etc. Primary Performance parameters are- mean effective pressure, fuel consumption , and change air pressure etc.
2.Visual monitoring-
These are the most commonly used systems. Such monitoring can be done using—
(A) Direct Methods- Human Eyes ears and senses, Optical probes
(B) Indirect Methods- Optical probes with Television etc., Photographs and videos, Radiographs, X rays, thermographs.
3. Vibration monitoring-
Vibration analysis is a process of looking for anomalies and monitoring change from the established vibration signature of a system. The vibration of any object in motion is characterized by variations of amplitude, intensity, and frequency. These can correlate to physical phenomena, making it possible to use vibration data to gain insights into the health of equipment. Vibration analysis can be used to:
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13. 4. Corrosion monitoring-
The Principles of Corrosion monitoring equipment is based on corrosion wear of the material. The use of such technique for condition monitoring of machines is very limited and selective. Few common corrosion monitoring technique are –
Weight loss method,
Electrical Resistance method,
Linear Polarization Resistance method,
Zero Resistance method,
Hydrogen monitoring method; etc.
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14. 5. wear debris monitoring-
Concentration and characterization of wear metals and other contaminants, suspended in used oil, mainly from the machine components, through which the oil interfaces and generates some wear metals and wear particles.
Contaminants (wear debris or wear particles) generated due to interaction between the various components / parts of the machine and carried away by the lubricant to sumps, these are known as Wear Debris Analysis or Contaminant Analysis or Wear Particle Analysis.
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15. Advantages of Condition Based Maintenance
Reduces the cost of asset failures
Improves equipment reliability
Minimizes unscheduled downtime due to catastrophic failure
Minimizes time spent on maintenance
Minimizes overtime costs by scheduling the activities
Minimizes requirement for emergency spare parts
Optimizes maintenance intervals (more optimal than manufacturer recommendations)
Improves worker safety
Reduces the chances of collateral damage to the system
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16. Disadvantages of Condition Based Maintenance
Condition monitoring test equipment is expensive to install, and databases cost money to analyze
Cost to train staff–you need a knowledgeable professional to analyze the data and perform the work
Fatigue or uniform wear failures are not easily detected with CBM measurements
Condition sensors may not survive in the operating environment
May require asset modifications to retrofit the system with sensors
Unpredictable maintenance periods
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17. Thank you For listening to me
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