Planned Preventive Maintenance (PPM)

Supporting Services&

FORECASTING MAINTENANCE REQUIREMENTS

PPMSupporting Services

For effective planned preventive maintenance, it is necessary to cater for adequate supporting

services such as those enumerated below:1. Facility register2. Equipment record sheet/card3. Maintenance schedules4. Work specifications5. Maintenance records and documentation6. Spare parts inventory

Facility registerEach organisation should maintain a register indicating all the machines/systems held in the organisation, which need to be maintained.

In a large organisation, ways and means should be introduced to subdivide the entire information into sections for easy availability to the users.

This can be done depending upon the maintenance needs or usage, as the needs of each section would be different.

Another classification of machines/systems can be done based on technical disciplines such as electronic, electrical, instrumentation, mechanical, hydraulic, civil, etc.

In a similar way, the maintenance crew can be identified for each group.

Nowadays computers are used to store all the relevant information regarding the performance and failure of machinery, which can assist in decision making as and when required.

Equipment record sheet/cardThis record is very useful when the maintenance work is

of repetitive nature as it contains all the relevant information such as the details of equipment in respect of services needed, spares supplied, lubrication used and other specifications.

The information given on the record sheet/ card proves very useful for maintenance work planning.

From this record, information can be transferred onto the equipment history card known as the log card.

The log card should move along with the equipment, whenever the equipment is shifted from one place to another.

Such a card is required to point out the equipment details. There are many types of history cards used, however, one

type for an electrical equipment is shown below.

EQUIPMENT LOG SHEET

Maintenance schedulesThis schedule indicates what work is to be done, at what

time and the estimated time required to complete the job. Separate schedules are prepared for each job, which are

carried out on each component/part as per the facility register.

For preparation of schedules, detailed information is required which can be taken from the records.

One schedule can be sufficient for small components/parts,

whereas for larger size equipment separate schedules are prepared for each of its component/parts such as engine, motor, hydraulic system, and controls, etc.

The schedules should contain full information regarding the work to be done.

Work specificationsThe exact maintenance work to be performed

varies according to the type of equipment and the type of maintenance selected.

The detailed work specification to be performed is specified on the job card for each of its elemental activities.

The job card gives the estimated time for each item of work to help in manpower planning and control.

Maintenance records and documentationThe maintenance records are necessary tools

for better planning; they aid the decision-making process as well

as improve efficiency. It is necessary to record the relevant

maintenance, though this is a costly function. The maintenance information can be

recorded in a variety of different formats, depending upon the depth and details to which the management decides to record such information.

Spare parts inventoryThe most important supporting service required for

the maintenance function is the issue of spare parts and their availability.

At times it is noticed that the equipment cannot be repaired for want of spare parts, particularly when the equipment used has been imported.

Therefore, it is most desirable to maintain adequate stock of spare parts depending upon the need,

so that the maintenance work does not suffer. For this purpose, a proper computerised information system related to spare parts inventory is necessary to be maintained.

The effective management of spare parts will minimise the downtime of equipment and ensure optimum utilisation of capital investment on spare parts inventory.

FORECASTING MAINTENANCE REQUIREMENTS

The generation of schedules for planned maintenance requires a critical study

so that a fair degree of accuracy may be achieved leading to minimisation of downtime of equipment, maximisation of equipment availability, and therefore, reduction in maintenance costs.

The statistical simulation techniques can be used for forecasting the needs of maintenance. For this purpose, the following breakdown

and repair time data of each critical component are carefully analysed.

a) A breakdown distribution that indicates the time for which a particular equipment will work without failure.

b) The repair time distribution to know the time required for a particular breakdown to be completed in order to restore the equipment to its normal working conditions.

.Knowing these distributions, the breakdown

can be forecasted through simulation and the repair time also can be known in advance to plan the manpower requirements.

These forecasts can be used to choose alternative maintenance policies for each equipment/facility.

BENEFITS OF PPMThe effective coordination of preventive

maintenance work between the operators and the maintenance staff can yield the following results.

1. Reduced Frequency of Failures2. Reduction in Manpower3. Reduction In Downtime

Reduced Frequency of FailuresThe frequency of failures can be reduced by

the introduction of a preventive maintenance programme,

because the failures can be detected in advance and repair work undertaken before the actual failure.

This also leads in reduction of production downtime.

Reduction in ManpowerUnder the planned preventive maintenance

programme the nature and volume of work is known in advance and

therefore it is possible for the management to plan the manpower as per requirements.

During inspections (scheduled), plans can be drawn for major works to be undertaken in future,

thus avoiding unnecessary delays involved in procurement of spare parts and special tools, etc. as required for the work.

Reduction In DowntimeBesides achieving reduction in downtime of

equipment, the PPM system also helps in reducing the overtime of

the maintenance personnel as the work is executed systematically.

Almost all the activities required to be performed are known and arrangements for their execution can be made

To make the maintenance work more interesting from the point of view of the maintenance crew, the concept of maintenance management by objectives can also be tried.

MAINTENANCE BY OBJECTIVES (MBO)

MAINTENANCE BY OBJECTIVES (MBO) It is a management method that can be

applied in the area of maintenance. The maintenance personnel can select the

areas where improvements in maintenance functions are possible.

Maintenance by objectives (MBO)is a real approach to meeting the set objectives. It can be useful in evaluating the performance of

a foreman, motivating the personnel to make commitments to achieve satisfactory results with their own objectives.

To obtain motivational value from an MBO programme,

the maintenance chief must be able to spell out his department objectives and then clearly communicate them to his foreman and other related persons.

For example,the manager may set an objective of reducing

the labour cost by five per cent. This objective may be based on the company

objectives to conduct maintenance at a fixed rate per unit produced.

Since reduction is in order, the manager must endeavour to improve the existing system to reduce the labour cost by five per cent.

Once the manager has made his objective clear, he must then guide the foreman to achieve this goal by reducing the overhead expenditure or by improving the performance of maintenance personnel.

For successful completion of maintenance by objectives, the following steps must be followed throughout the life of the programme.1. List out the common goals of the maintenance department

and specify the responsibility with accountability for each of the goals.

2. Specify the role of each and every maintenance person so that they can be held responsible for any deficiency in completion of the MBO programme,

3. To meet the goals/objectives, commitment U> targeted dates is important for all. For example, the preparation of proper schedules for every job by a targeted date.

4. If the targeted dates for the completion of jobs have slipped, a programme for review of the work must be drawn.

5.  5. When the objectives are met, it must be made known to all the concerned persons and the key persons must be rewarded lor their achievement

DEVELOPMENT OF CHECKLISTS

DEVELOPMENT OF CHECKLISTSGenerally, the manufacturer along with the machine

supplies the checklists as well. They also modify and update the checklists during the

guarantee period when they take up the different maintenance jobs.

Whether a particular equipment or system will be brought under preventive maintenance and whether some items of the equipment or system would be brought under checklist inspection, depend on a number of factors such as those enumerated below;

1. Criticality of the item2. Availability of standby equipment/facility3. Cost analysis4. Expected service life5. Technology advancement and rapidity of slipping into

obsolescence.

While developing the checklists, the following steps need to be considered:1. The total number of subsystems that the machine or system is

comprised of.2. Analysis of the functioning of these subsystems and identi fication of

their critical components3. Identification of the indicators of functional behaviour of the critical

components. These may include:  Abnormal sound Vibrations Leakage of fluid Wear Cleanliness Play Cracks Change in colour Corrosion Temperature of bearings Electrical failure Performance of electrical connections Power/fuel consumption

4. Determination of the normal, alarming and dangerous level of behaviour of components/equipment, etc.

5. From previous experience, determination of the safe period of withstanding the abnormal behaviour

6. Determination of the periodicity of inspection of the various indicators. This depends on:

 Age and condition of the assetSeverity of serviceSafety requirementsHours of operationSusceptibility to wearSusceptibility to damageSusceptibility to deviations from normal adjustments7. Development of a proper format for conducting

the checks and formulating the reports.