7th
Worker Utilization Ut =
(CM Effort + PM Effort)/total effort
Number of Downtimes
(MTTF/MTBM)-1
A =
(total time - total downtime)/total time
The road from a purely reactive program to a RCM program
- Develop a Master equipment list identifying the equipment in the facility - Prioritize the listed components based on importance or criticality to operation, process, or mission - Assign components into logical groupings - Determine the type and number of maintenance activities required and periodicity - Assess the size of maintenance staff - Identify tasks that may be performed by operations maintenance personnel - Analyze equipment failure modes and impacts on components and systems - Identify effective maintenance tasks or mitigation strategies
First Generation
- Downtime did not matter much - Prevention of equipment failure was not a very high priority in the minds of most managers - Most equipment was simple and much of it was over-designed - Equipment were reliable and easy to repair - No need for systematic maintenance, only simple cleaning, servicing and lubrication routines - The need for skills was also lower than it is today
Reliability Centered Maintenance Hierarchy (Preventive Element Applications)
- Equipment subject to wear - Consumable equipment - Equipment with known failure patterns - Manufacturer recommendations
Reliability Centered Maintenance Hierarchy (Predictive Element Applications)
- Equipment with random failure patterns - Critical equipment - Equipment not subject to wear - Systems which failure may be induced by incorrect preventive maintenance
Reliability Centered Maintenance Hierarchy (Corrective Element Applications)
- Small parts and equipment - Non-critical equipment - Equipment unlikely to fail - Redundant systems
Predictive Maintenance
- Techniques that help determine the condition of in-service equipment in order to predict when maintenance should be performed and to minimize disruption of normal system operations - Others define predictive maintenance as a maintenance scheduling tool that uses vibration and infrared or lubricating oil analysis data to determine the need for corrective maintenance actions
The benefits of Condition Monitoring (CM)
- gives early detection of wear-out/damage - Better prediction of maintenance requirements - minimizes unnecessary shutdowns and opening up of the plant - gives reassurance of safe continued operation - saves costs- reduced spare usage - Energy saving - helps to create team work basis within different work disciplines - improves product quality, customer relations, plant design, company
OEE =
A*P*Q
Filling by manufactures
Advantage: Commonly used Disadvantage: Manufactures changes overtime
Easiest arrangement: Filling information in a single file
Advantage: Easy to fill information Disadvantage: It's hard to find information
Next less arrangement: Filling information by equipment
Advantage: Very accurate way to find information Disadvantage: Complicated in filling and retrieving information
Slightly less arrangement: Filling information by building
Advantage: easy to find information easily Disadvantage: Hard to save information as caring for filing the information and place it in the right place
Third Generation
After the 1970, the process of change in industry has gathered even greater momentum. - Downtime has always affected the productive capability of physical assets by reducing output, increasing operating costs and interfering with customer service - Just-in-time systems, mean that quite small breakdowns are now much more likely to stop a whole plant - Reliability and availability have now also become key issues in different sectors - Safety or environmental consequences, as more and more failures became serious, at a time when standards in these areas are rising rapidly
MTTR =
CM downtime / number of CM
Thermal Techniques
Infra-red cameras are most widely used to capture thermal images of the equipment
Wrench time
Is the primary measure of workforce efficiency and planning and scheduling effectiveness
Wear Debris Monitoring Technique (Lube Oil Analysis)
It monitors lubricant condition and monitors presence of wear particles in oil
Availability =
MTTF/(MTTF + Downtime)
MTTM =
PM downtime / number of PM
Mission: Estimates Based on Planner Expertise
Planners use personal experience and file information to develop work plans and estimated time to avoid work delays and quality or safety problems
Total loss =
Production Downtime loss + Technician loss + Spare Part Cost
Second Generation
The period 1960-1970 generated three fundamental mutations in the industrial's maintenance's approach: - Creating the diagnostic maintenance, that led lately to the conditioned maintenance - The concept of "failure cost" appeared and the indirect financial incidence of the activity of maintenance is considered - The appeal to the reliability theory. The reliability models of studies, which were initially hard to apply in the industrial units, were, subsequently, used more and more
Using engineers as planners
They do not possess the skill to plan most main jobs
Use of 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
TEEP =
U*OEE
NEE =
Up*P*Q
Vibration Monitoring
Used for Condition Monitoring of rotating and reciprocating machines. There are wide ranges of techniques and instruments available
•Using apprentices as planners. •Using engineers as planners
Using supervisors as planners
Maintenance is
a group of actions taken to prevent a device or component from failing or to repair normal equipment degradation experienced with the operation of the device to keep it in proper working order
The useful life region is characterized by
a low, constant failure rate . Here all weak components have been removed: design, manufacture, installation, operating and maintenance errors rectified so that failure is due to a variety of unpredictable lower level causes
Reliability Centered Maintenance (RCM)
a process used to determine the maintenance requirements of any physical asset in its operating context
Preventive Maintenance
actions performed on a time or machine-run-based schedule that detect, preclude, or mitigate degradation of a component or system with the aim of sustaining or extending its useful life through controlling degradation to an acceptable level
P =
actual quantity/target quantity
RCM is highly reliant on predictive maintenance but
also recognizes that maintenance activities on equipment that is inexpensive and unimportant to facility reliability may best be left to a corrective maintenance approach
Application and parameters are developed for each type of machines or plant items,
and usually require measurement of quantities such as temperature, pressure, flow, and speed
All repairs are well planned, implemented by properly trained craftsmen,
and verified before the machine or system is returned to service
All deviations from optimum operating condition, i.e., efficiency, production capacity and product quality,
are corrected when detected
Basically, predictive maintenance differs from preventive maintenance by
basing maintenance need on the actual condition of the material/equipment rather than on some pre-set schedule; preventive maintenance is time-based
RCM program advantages and disadvantages mirror those of predictive maintenance
because RCM is so heavily weighted in utilization of predictive maintenance technologies
The early region is characterized by
decreasing with time. When items are new, especially if the element is a new design, early failures can occur due to design faults, poor quality components, manufacturing faults, installation errors, operator and maintenance errors
It also approaches the structuring of a maintenance program recognizing that a facility
does not have unlimited financial and personnel resources and that the use of both need to be prioritized and optimized
R =
exp(-MTBM/MTTF)
The wear-out region is characterized by
increasing with time as individual items approach the end of the design life for the product; long life components which make up the element are new wearing out
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.
Reactive Maintenance
is basically the "run it until it breaks" maintenance mode. No actions or efforts are taken to maintain the equipment as the designer originally intended to ensure that the design life is reached
Performance Monitoring and Analysis
is less well known, yet where deterioration in the condition of a machine results in an increase in energy usage
The principal concept of corrective maintenance
is that proper, complete repairs of all incipient problems are made on and as needed basis
Corrective Maintenance
is when you fix a fault in a system that is still running within acceptable ranges but is noticeably deteriorating quickly or nearing unsafe operation. ex., replacing a partially exposed wire
Maintenance is a philosophy because
it must be carefully fitted to the operation or organization it serves and because the way it is viewed by its executors will shape its effectiveness
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
It recognizes that all equipment in a facility is
not of equal importance to either the process or facility safety
MTBF =
operating time/ number of CM
MTBM =
operating time/ number of PM
Equipment Utilization Ut =
operating time/available time
Principle 4: Estimated Based on Planner Expertise
planner expertise order job estimates
Principle 3: Component Level Files
planners base their files on the component level of systems
Principle 2: Focus on Future Work
planners concentrate on future work
Principle 5: Recognize the Skill of the Crafts
planners organize jobs according to the skill of the crafts
Q =
sound quantity/actual quantity
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
Principle 1: Separate Group
the company organizes planners into a separate department
The objective of maintenance is
to bring whatever is being maintained towards a state of failure-free operation
The aim of maintenance is
to find an optimum situation, taking into account the increasing costs of increasingly sophisticated maintenance, as well as costs resulting from increasingly high failure rates
Feedback is given by the lead technician or supervisor to the planning department
to help avoid similar problems in the future
The Cost benefit of CM only comes
when action is taken on CM recommendations resulting in Condition Based Monitoring (CBM)
It recognizes that equipment design and operation differs and that different equipment
will have a higher probability to undergo failures from different degradation mechanisms than others
Principle 6: Measure Performance with Work Sampling
work sampling for direct work time provides the primary measure of planning effectiveness
Advantages of Reliability Maintenance
• Can be the most efficient maintenance program • Lower costs by eliminating unnecessary maintenance or overhauls • Minimize frequency of overhauls • Reduced probability of sudden equipment failures • Able to focus maintenance activities on critical components • Increased component reliability
Disadvantages of Reliability Maintenance
• Can have significant start-up cost, training, equipment, etc. • Savings potential not readily seen by management
Disadvantages of Preventive Maintenance
• Catastrophic failures still likely to occur • Labor intensive • Includes performance of unneeded maintenance • Potential for incidental damage to components in conducting unneeded maintenance
Advantages of Preventive Maintenance
• Cost effective in many capital-intensive processes • Increased component life cycle • Energy savings • Reduced equipment or process failure • Reduces costly down time • Estimated 12% to 18% cost savings over Corrective maintenance program
Advantages of Predictive Maintenance
• Increased component operational life/availability • Decrease in equipment or process downtime • Decrease in costs for parts and labor • Better product quality • Improved worker and environmental safety • Energy savings • Estimated 8% to 12% cost savings over preventive maintenance program
Disadvantages of Reactive Maintenance
• Increased cost due to unplanned downtime of equipment • Increased labor cost, especially if overtime is needed • Cost involved with repair or replacement of equipment • Possible secondary equipment damage from equipment failure • Equipment not maximized
Disadvantages of Predictive Maintenance
• Increased investment in diagnostic equipment • Increased investment in staff training • Savings potential not readily seen by management
Disadvantages of Corrective Maintenance
• Increased long term costs due to unplanned downtime of equipment • Possible secondary equipment or process damage from equipment failure • Prone to neglect of assets
Advantages of Corrective Maintenance
• Lower short term costs • Less staff
Advantages of Reactive Maintenance
• Lower start up cost • Less staff • No maintenance cost
Examples of Preventive Maintenance
• Oil changes • Greasing • Changing filters • Belt tightening
Mission: Recognize the skill of the crafts
• The planning department recognizes the skill of the crafts • The planner's responsibility is 'What' before 'How' • The planners have not to put much detail in each plan • The planner determines the scope of the work request
Examples of Predictive Maintenance
• Vibration Analysis • Infrared Thermography • Oil Analysis • Visual Inspections
Feedback consists of
•Any problems. •Any plan changes. •Any other helpful information
To maintain that planer work well
•Company is keeping open an option to revert the planners back into the work force if planning does not work •Company may leave an avenue to replace one or two planners that do not work well.
Mission: Focus on Future Work
•Concentrate on future work "the work that has not been started" •At least one week of work should be planned, approved, and ready to execute •The Crew handle the current day's work and any problems arise after the commencement of any job are resolved by the craft supervisors
•The crew supervisor focuses on executing assigned work so he receives too much pressure so may use the planner to assist work that has already begin •There is also a management problem; where the planner is reporting to the crew supervisor not to the manager himself. And this leads to
•Crew supervisor may assign craft work to a planner and this leads to planner forget about planning work •Crew members will place more importance to work on progress than paper work
Solutions to Focus on Future Work
•Designate one of the planners for helping all jobs in progress to shield others •After the job start, the technicians or supervisor must find additional information.
Component level file (Mini-files)
•It's the vital key for successful planning. •Planners make new equipment mini-file when it's purchased. •Planners label the exact same component tag number attached to the equipment in the field •The files are arranged in a secure fashion to keep data from taken or lost
What are companies do to attract the best crew to make planning work
•Pay planners at or above the first line level •Provide an additional promotion
Mission and Responsibilities of Separate Group
•Planners are not a member of the crew for which they plan •The crew members execute work; the planners do not •Each planner should concentrate on his planning work •Planners report to a different supervisor that of the crew •There may be a lead planner with some responsibilities
Reasons of second school(There is freedom for technicians to change the plan)
•Planners do not possess perfect information •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 •Planners do not have time to develop a detailed procedure for every job
Planner main job
•Search for needed information through equipment and other information sources •Collecting feedback from technicians and supervisors •Saving all data collected in files and update file always •Planning for future and update the plans with any new information
How to sample
•Study conducts observation over several weeks or months •Observer has a list of maintenance employees at the plant •Categorize work done •Person conduct studies have to be familiar and agreeable.
Why wrench time is important
•Tells directly if the object of planning is being met •Measure how well planning is working •Review of performance make it visual to everyone how they are progress or they are different
Reasons of first school(Technicians must execute jobs exactly as planned)
•The planner access to necessary information including specifications history and engineering to develop the proper job plan •Restriction promotes consistency of job execution •Restriction execution to the plan ensures reliable history records without having to count on accurate job feedback
Problems facing Focus on Future Work
•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 •Each planner puts a future plans for 20 to 30 technician in on going work, future work may be missed .
Estimates Based on Planner Expertise dictates that
•The plant must choose it's planners from best craft person •The plant has to decide what level of skill planning required •The plant must decide the appropriate method of estimating job time requirements
Solutions of Separate Group
•The supervisor may assign more capable technicians to difficult jobs. •Supervisor may decide over-time work for the crew. •Supervisor may extend the job duration and not to finish on schedule. •Supervisor may take the advantage of an existing contract. •Supervisor may request help from another crew.
Using apprentices as planners
•They have lack of experience •Experienced craft persons receiving a job plan from an apprentices tend to cast doubt
