Final Revision

The four known fixes for resonance are

1. Change speed. 2. Change the natural frequency of the responding part with added mass or stiffness. 3. Add damping or dynamic absorber. 4. Reduce the source vibration input.

An Accelerated testing program can be broken down into the following steps

1. Define objective and scope of the test 2. Collect required information about the product 3. Identify the stress(s) 4. Determine level of stress(s) 5. Conduct the Accelerated test and analyze the accelerated data

The data obtained is analyzed to

1. Detect signs of degradation. 2. Diagnose cause of fault. 3. Predict for how long it can be safely or economically run.

Corrective Methods

1. Disassembly, visual inspection, cleaning, and re-assembly can fix some elusive problems. 2. Bearing replacement. 3. Identifying other bad parts and replacing them. 4. Mass balancing. 5. Alignment. 6. Lubrication. Just greasing noisy bearings can quiet them, but changing the lubrication schedule can extend their lives. 7. Structural stiffening to raise natural frequencies (Mass loading and stiffening can reduce any measured vibration).

False priority leads to

1. High improper interrupt work. 2. Works begin without proper preparation.

Interruption of low priority jobs when more urgent jobs arise

1. If true emergency arises, it is appropriate to delay another job. 2. If urgent job is not emergency, it should be worked as the next job without any interruption. 3. If non urgent job, it should wait until the next day or week.

The resonance tests are

1. Impact testing of the major components to find their natural frequencies. 2. Run up or coast down. 3. Operating deflection shapes. 4. Variable speed shaker.

By implementing these principles, it is possible to

1. Increase company's productivity. 2. Regain control of backlog. 3. Eliminate guesswork. 4. Quickly adjust to unexpected situations and specific needs. 5. Improve the overall company efficiency dramatically.

Features of ISO 10816

1. Measurements are made in three direction (horizontal, vertical, axial). 2. ISO 10816 keeps the lower frequency range flexible between 2 and 10 Hz, depending on the machine type. The upper frequency is 1000Hz. 3. ISO 10816 operates with the term vibration magnitude, which, depending on the machine type, can be an RMS value of vibration velocity, acceleration or displacement. 4. The standard consists of several parts, each treating a certain type of machines, with tables of limit values differentiating between *acceptable* vibration (*green* range), *unsatisfactory* vibration (*yellow* range), and vibration that *will cause damage* unless reduced (*red* range).

Examples of Preventive Maintenance

1. Oil changes 2. Greasing 3. Changing filters 4. Belt tightening

Scheduling Principles

1. Plan for the Lowest Required Skill Level. 2. Schedules and Job Priorities are Important. 3. Schedule from Forecast of Highest Skills Available. 4. Schedule for Every Work Hour Available. 5. Crew Leader Handles Current Day's Work. 6. Measure Performance with Schedule Compliance.

Importance of Schedule compliance

1. Provides a measure of accountability. 2. Guards against crews working on pet projects not more important than allocated work. 3. Facilitates discussion and identification of plant problems between maintenance managers and supervisors. (diagnostic tool)

Scheduler main job (who is apart from the crew supervisor)

1. Selects the week's worth of work from the overall plant backlog. 2. Uses a forecast of the capabilities of the crew for coming week. 3. Uses priority and job plan information.

Steps of Predictive Maintenance Program

1. Sensor Implementation and data streaming connections. 2. Collect Performance Data. 3. Optimize failure beginning. 4. Leverage data science until unplanned downtime can be avoided. 5. Reach a smart predictive maintenance program.

Planning Principles

1. Separate Group. 2. Focus on Future Work. 3. Component Level Files. 4. Estimate Job Based on Planner Expertise. 5. Recognize the Skills of the Craft. 6. Measure Performance with Work Sampling.

How to sample

1. Study conducts observation over several weeks or months 2. Observer has a list of maintenance employees at the plant 3. Categorize work done 4. Person conduct studies have to be familiar and agreeable

Steps of Liquid Penetrant Testing

1. Surface Preparation 2.Penetrant Application 3. Penetrant Dwell 4. Excess Penetrant Removal 5. Developer Application 6. Indication Development 7. Inspection 8. Clean Surface

Problems facing "Focus on Future Work": 1. The planner has the duty to help technology to find file in information for jobs has already begin. In this way, planner will concentrate about on going work and forget about the future planning. 2. Each planner puts a future plans for 20 to 30 technician in on going work, future work may be missed .

Solutions: 1. Designate one of the planners for helping all jobs in progress to shield others 2. After the job start, the technicians or supervisor must find additional information.

Problems facing "Separate Group": 1. Crew supervisor may assign craft work to a planner and this leads to planner forget about planning work 2. Crew members will place more importance to work on progress than paper work

Solutions: 1. The supervisor may assign more capable technicians to difficult jobs. 2. Supervisor may decide over-time work for the crew. 3. Supervisor may extend the job duration and not to finish on schedule. 4. Supervisor may take the advantage of an existing contract. 5. Supervisor may request help from another crew.

Reliability is

The probability that a functional unit will perform its required function for a specified interval under stated conditions or, is the ability of something to "fail well" (fail without catastrophic consequences).

Schedule compliance

is the measure of adherence to the 1-week schedule and its effectiveness. (is the ultimate measure of proactivity).

Wrench time/work sampling

is the primary measure of workforce efficiency and of planning and scheduling effectiveness.

Job duration

is the straight calendar time that technicians work on the equipment

*Reliability testing*: purpose of reliability testing is to discover potential problems with the design as early as possible and, ultimately, provide confidence that the system meets its reliability requirements. Reliability testing may be performed at several levels. Complex systems may be tested at component, circuit board, unit, assembly, subsystem and system levels.

*Accelerated testing*: purpose of accelerated life testing is to induce field failure in the laboratory at a much faster rate by providing a harsher, but nonetheless representative, environment. For systems that must last many years, reliability engineering maybe used to design an accelerated life test as well.

*Vibration Monitoring* 1. Detects vibration failures at reciprocating motion. 2. Every fault has its own fingerprint. 3. Hard to apply. it is valuable but too often overly complicated.

*Acoustic Emission* 1. Detects vibration failures at rest. (stationary) 2. Analysis must be done to diagnose failures. 3. Easily applied in gas turbines, bridges, airplane wings.

Advantages and Disadvantages of 120%, 100% and 80%

*Advantages of 100%*: 1. For accountability and clarity of communication. 2. Keeps the crew busy accomplishing a practical goal. *Disadvantages of 100%*: Some jobs that can be easily interrupted in case emergencies arise. *Advantages of 120%*: This strategy sets a more ambitious goal for work completion because it encourage the crew to stay busy. *Disadvantages of 120%*: 1. Difficult to gauge the performance of the crew. 2. Management has a difficult time comparing what the crew did accomplish to what it should have been able to do. 3. Maintenance coordination with plant operators and other crafts may be more difficult. *Advantages of 80%*: 1. Provide enough work for the crew in case operators could not finish some of the jobs. 2. Encourage work order originators to claim false emergencies knowing the availability of the resource. *Disadvantages of 80%*: 1. Difficult to gauge the performance of the crew 2. Management has a difficult time comparing what the crew did accomplish to what it should have been able to do. 3. The crew might complete less work than possible.

*Advantages of Reactive Maintenance* 1. Lower start up cost 2. Less staff 3. No maintenance cost *Disadvantages of Reactive Maintenance* 1. Increased cost due to unplanned downtime of equipment 2. Increased labor cost, especially if overtime is needed 3. Cost involved with repair or replacement of equipment 4. Possible secondary equipment damage from equipment failure 5. Equipment not maximized

*Advantages of Corrective Maintenance* 1. Lower short term costs 2. Less staff *Disadvantages of Corrective Maintenance* 1. Increased long term costs due to unplanned downtime of equipment 2. Possible secondary equipment or process damage from equipment failure 3. Prone to neglect of assets

*Advantages of Preventive Maintenance* 1. Cost effective in many capital-intensive processes 2. Increased component life cycle 3. Energy savings 4. Reduced equipment or process failure 5. Reduces costly down time• Estimated 12% to 18% cost savings over Corrective maintenance program *Disadvantages of Preventive Maintenance* 1. Catastrophic failures still likely to occur 2. Labor intensive 3. Includes performance of unneeded maintenance 4. Potential for incidental damage to components in conducting unneeded maintenance

*Advantages of Predictive Maintenance* 1. Increased component operational life/availability 2. Decrease in equipment or process downtime 3. Decrease in costs for parts and labor 4. Better product quality 5. Improved worker and environmental safety 6. Energy savings 7. Estimated 8% to 12% cost savings over preventive maintenance program *Disadvantages of Predictive Maintenance* 1. Increased investment in diagnostic equipment 2. Increased investment in staff training 3. Savings potential not readily seen by management

Reliability Centered Maintenance Hierarchy

*Corrective* Element Applications: 1. Small parts and equipment 2. Non-critical equipment 3. Equipment unlikely to fail 4. Redundant systems *Preventive* Element Applications: 1. Equipment subject to wear 2. Consumable equipment 3. Equipment with known failure patterns 4. Manufacturer recommendations *Predictive* Element Applications: 1. Equipment with random failure patterns 2. Critical equipment 3. Equipment not subject to wear 4. Systems which failure may be induced by incorrect preventive maintenance

*Root Mean Square* 1. the simplest way of measuring vibration. 2. The vibration is measured over a wide frequency range, such as 10-1000 Hz or 10-10000 Hz.

*Crest Factor* 1. Crest Factor(Peak-to-RMS ratio) of the vibration is capable of giving an earlier warning of bearing defects. 2. As the fault progresses, more peaks will be generated until finally the RMS vibration increases but the Crest Factor decreases.

*S-N curve*: plot of the maximum applied stress against the mean number of cycles to failure. S-N curves can be found in the technical literature for many metals.

*Miner Damage Rule*: The significant contributor to cumulative fatigue damage is the low stress, and the high cycle load situation. The measure of cumulative damage that is used is the Palmgren-Miner rule. * D = sigma i=1 to K of: (ni/Ni) <= 1 *

*Reasons of first school (Technicians must execute jobs exactly as planned)* 1. The planner access to necessary information including specifications history and engineering to develop the proper job plan 2. Restriction promotes consistency of job execution 3. Restriction execution to the plan ensures reliable history records without having to count on accurate job feedback

*Reasons of second school (There is freedom for technicians to change the plan)* 1. Planners do not possess perfect information 2. Planners do not have the time to review these technicians reasons for changing the job plan for improvement during the course of each job while in progress 3. Planners do not have time to develop a detailed procedure for every job

Explain Some NDT

*Ultrasonic inspection*: Ultrasonic waves are transmitted through test material. Ultrasonic echoes and reflections indicate discontinuities in the material. *Magnetic particle inspection*: Test object is magnetized, then magnetic particles applied to surface accumulate over the area where the magnetic field leaks as a result of surface or sub-surface defects. *Radiography*: Penetrating radiation emitted by X-ray generator or isotope source is imposed on a test component. Radiation transmitted or attenuated by the component is used to detect internal flaws within the component. *Eddy current inspection*: Localized alternating currents induced in test component. Change of impedance value from magnetic field surrounding secondary/eddy current indicates flaws. *ACPD*: A uniform electric current is injected between two contact points on the surface of a component. The potential difference between the two points is used to size the crack for depth.

Machine vibration has several categories of causes that are discovered sometimes after repair. The major categories are

1. *Design defects*. a. mostly structural related with active resonances built-in because of improper sizing and proportioning of the parts. b. Statically, the structure is O.K., but is dynamically weak. c. not discovered until the machine is energized and brought up to speed. d. corrected on-site with strategic stiffeners added. 2. *Manufacturing defects*. a. built-in during the casting, machining, heat-treating, and assembly processes. b. difficult to control. c. impossible to predict. d. elusive to fix. 3. *Operational stresses*. a. develop due to material build up or erosion that changes the balance condition. b. thermal expansion that changes component alignment. c. cause high dynamic loads at the bearings which lead to accelerated wear-out d. easily detected with periodic vibration measurements and there are well established methods to correct them on-site. 4. *Maintenance actions*. a. the most common cause of machine failure. b. Some of this is due to rough handling. c. Some is simply the fact that field repair is less controlled than the original factory build. 5. *Aging*. a. can only be detected with long term vibration monitoring. b. The two dominant aging effects are Residual stresses and Softening of structural joints.

Three Pillars to Successful Proactive Maintenance

1. *New Program Start Up*: set a jump-off point and a vision for the future of the program. 2. *Technology Selection*: Different assets require a mix of technologies, including mechanical, electrical and process. 3. *Data Management*: supported by a CMMS or SaaS software to support data capturing and analysis.

Condition Monitoring Techniques

1. *Thermal Techniques.* This technique can be effectively used for knowing insulation breakdown and leaks in the pipe work, and High resistance joints, hot motors blocked cooling paths in electrical machines. 2. *Wear Debris Monitoring Technique (Lube Oil Analysis)*. It monitors lubricant condition and monitors presence of wear particles in oil 3. *Vibration Monitoring*. Used for Condition Monitoring of rotating and reciprocating machines. There are wide ranges of techniques and instruments available 4. *Performance Monitoring and Analysis*. is less well known, yet where deterioration in the condition of a machine results in an increase in energy usage and usually require measurement of quantities such as temperature, pressure, flow, and speed 5. *Ultrasonic Measurement*. is another technique which proves beneficial for monitoring of leaks in pressurized and vacuum systems, Mechanical contact systems including under or over lubrication, leaking or failed valves etc.

Environmental factors which affect a component's failure rate include

1. Ambient temperature. 2. Humidity. 3.Salt (causes corrosion, particularly when allied with high humidity). 4. Vibration. 5. Acceleration(Mechanical Shock). 6. Radiation. 7. Low Pressure(space vehicles) or High Pressure (underwater vehicles). 8. Dust.

Examples of proactive maintenance include

1. Applying corrosion inhibitor coatings to metallic surfaces. 2. Performing inspections to look for cracks, leaks and rust spotting. 3. Performing tests to look for surface material thinning or erosion of pipelines. 4. Lubricating machines to reduce wear, tear and diffusion corrosion.

Three fundamental mutations in the industrial's maintenance's approach are

1. Creating the *diagnostic maintenance*, that led lately to the conditioned maintenance. 2. The concept of *failure cost* appeared and the indirect financial incidence of the activity of maintenance is considered. 3. The appeal to the *reliability theory*. The reliability models of studies, which were initially hard to apply.

The road from a purely reactive program to a RCM program is not an easy one. The following is a list of some basic steps that will help to get moving down this path

1. Develop a Master equipment list identifying the equipment in the facility. 2. Prioritize the listed components based on importance or criticality to operation, process, or mission. 3. Assign components into logical groupings. 4. Determine the type and number of maintenance activities required and periodicity. 5. Assess the size of maintenance staff. 6. Identify tasks that may be performed by operations maintenance personnel. 7. Analyze equipment failure modes and impacts on components and systems. 8. Identify effective maintenance tasks or mitigation strategies.

Considering aspects of Condition Monitoring

1. Does the technique give information about the mode of failure already identified? 2. Is the technique practical to apply? 3. Is it the cost-effective technique? 4. Is it the simplest method available?

File arrangement types

1. Easiest arrangement: Filling information in a single file. 2. Slightly less arrangement: Filling information by building. 3. Next less arrangement: Filling information by equipment. 4. Filling by Manufactures.

Other maintenance activities that affect vibration are

1. Excessive localized heating, like welding on a shaft. 2. Too high belt tension. 3. Shaft, or bearing, misalignment. 4. Substandard replacement parts. 5. Lack of lubrication. 6. Loose hardware. 7. Replacing hardware with different weights that affect balance. 8. Hammering on a bearing. 9. Unclean, or burred, precision machine surfaces.

Requirements of Predictive Maintenance Program

1. Identification of the machines, based on criticality, to be covered under Predictive Maintenance Program. 2. Identification of technique to be applied for individual machines covered under the system. 3. Procurement of relevant instrumentation. 4. Trained manpower for operating the instruments for collecting data. 5. Establishment of baseline data for each machine. 6. Establishing the time intervals for collection of data for each machine. 7. Storage of the collected data in the database. 8. Analysis of the data and its comparison with baseline data for identifying the condition of the machine. 9. Planned intervention and correction for the machines running under precarious condition.

Improved the work-force's efficiency

1. Reducing delays that keep technicians from completing work orders. 2. Planning individual jobs can reduce delays such as waiting to obtain certain parts, tools, or technician instructions. 3. Not having a sufficient amount of work assigned may encourage technicians to take excessive breaks.

Importance of priority system

1. Schedule work will assign and complete. 2. Ensure that sufficient and right amount of work is assigned.

Planner main job

1. Search for needed information through equipment and other information sources. 2. Collecting feedback from technicians and supervisors. 3. Saving all data collected in files and update file always. 4. Planning for future and update the plans with any new information.

Wrench time is important because it

1. Tells directly if the object of planning is being met 2. Measures how well planning is working 3. Reviews performance and makes it visual to everyone how they are progress or they are different

Proactive work includes

1. The advance schedule selects a 1-week period for making an advance allocation of the work. 2. Having a person separate from the crew supervisor allows a system of checks and balances. 3. The crew supervisor must make a labor forecast in terms of the highest skills available. 4. The scheduler receives a labor forecast from each crew supervisor. 5. The scheduler will use information from job plans.

The symptoms of natural vibrations, or resonance

1. The vibration is very bad, in other words, abnormally high amplitude. 2. The vibration is strongly directional. 3. The amplitude is not steady, but varies up and down. 4. Rumbles during run-up or coast-down.

Non-Destructive Testing (NDT)

1. Visual inspection 2. Ultrasonic inspection 3. Liquid penetrant inspection 4. Magnetic particle inspection 5. Ferrous Wire Rope Testing 6. Radiography 7. Eddy current inspection 8. ACPD

If the element is a new design, early failures can occur due to

1. design faults. 2. poor quality components. 3. manufacturing faults. 4. installation errors. 5. operator and maintenance errors.

Vibration measurement can generally be characterized as falling into three categories

1. detection 2. diagnosis 3. prognosis.

The benefits of Condition Monitoring

1. gives early detection of wear-out/damage 2. Better prediction of maintenance requirements 3. minimizes unnecessary shutdowns and opening up of the plant 4. gives reassurance of safe continued operation 5. saves costs- reduced spare usage 6. Energy saving 7. helps to create team work basis within different work disciplines 8. improves product quality, customer relations, plant design, company. 9. The Cost benefit of CM only comes when action is taken on CM recommendations resulting in Condition Based Monitoring (CBM).

Maintenance is mainly related to downtime as it can

1. reduce the probability of downtime. 2. increase the overall equipment effectiveness. 3. make downtime optional and limited, not compulsory.

Downtime has always affected the productive capability of physical assets by

1. reducing output. 2. increasing operating costs 3. interfering with customer service.

Daily scheduling is better because

1. there is a wide variance between planned and actual times. 2. The crew supervisors need to understand the specific abilities of their various technicians.

What happen when the Job finished in time less/more than planned for it?

1. when the Job finished in time less, the supervisor may have to assign additional work to begin a day earlier than expected. 2. when the Job finished in time more, the supervisor may have to schedule additional time for the next day.

Reliability Test Requirements

Testing Parameters: 1. Maturity 2. Fault tolerance 3. Recoverability 4. Availability Problems: A single test is insufficient to generate enough statistical data. Multiple tests or long-duration tests are usually very expensive.

Failure Cost

The cost resulting from the occurrence of defects in products returned over the manufacturer, or the cost evolved when maintenance actions are ignored resulting in higher cost of labor, spare parts and downtime.

Life Cycle Cost (LCC) it was applied and developed In USA, which covers the totality of the costs of the research, design, construction, exploit and maintenance processes for an equipment's entire life. The objective aimed is the minimization

Total Productive Maintenance (TPM) the Japanese philosophy of maintenance , which approaches it from a human point of view. Its objective is the maximization of the equipment's global efficiency and it presupposes the participation of all the "actors" that contribute to its efficiency: the designers, the users (the production staff), the maintenance staff, from all the management's hierarchical levels, starting with the worker to the general manager

Design For Reliability is

an emerging discipline that refers to the process of designing reliability into products. This process encompasses several tools and practices and describes the order of their deployment that an organization needs to have in place to drive reliability into their products.

Work hours

are the individual labor hours required by each technician.

A pencil sharpener maybe more reliable than an airliner,

but has a much different set of operational conditions, insignificant consequences of failure, and a much lower budget.

Reason of low schedule compliance

for telling what other work had to interrupt the schedule.

stress range is

the difference between the maximum tensile stress and the minimum (compressive) stress that may occur in a particular joint due to a variety of applied loads.

The reason for determining early whether the vibration is forced or natural is because

the fixes are completely different. 1. *Forced* vibrations on machines are corrected by mass balancing, aligning, or changing the bad parts. 2. *Natural* vibrations are a structural effect, where some structure behaves like a mechanical amplifier that is frequency sensitive.

Reliability modelling is

the process of predicting or understanding the reliability of a component or system. Two separate fields of investigation are common: 1. *Physics of failure approach*: Uses an understanding of the failure mechanisms involved, such as crack propagation or chemical corrosion. 2. *Parts stress modelling approach*: Is an empirical method for prediction based on counting the number and type of components of the system, and the stress they undergo during operation.

Advance allocation means

the schedule will select all the work that the crew should be able to finish in a single week

fatigue limit is

the stress level below which an infinite number of loading cycles can be applied to a material without causing fatigue failure.