4. British Standard Glossary of terms (3811:1993) defined
maintenance as:
“The combination of all technical and administrative
actions, including supervision actions, intended to retain
an item in, or restore it to, a state in which it can
perform a required function”.
Maintenance is a set of organised activities that are
carried out in order to keep an item in its best
operational condition with minimum cost acquired.
BITS Pilani, Pilani Campus
5. Why Maintenance Management
Modern maintenance management is not to repair broken equipment rapidly.
Modern maintenance management is to keep the equipment running at high
capacity and produce quality products at lowest cost possible.
There are many reasons why maintenance is becoming more and more important.
In developing countries , where many old machines are operating, the spare part
problem are arising. Some times it is difficult to find spare parts for equipment
and if it is possible to find them, they are usually very expensive and must be paid
on foreign currency.
Due to long lead times of supply of spares, it is common that the spare part
inventory is growing bigger than necessary. A very essential part in maintenance
management is developing countries to reduce the need of spare parts, as well as
to maintain the minimum level of shock to save foreign currency, but still keeping
the productivity high.
BITS Pilani, Pilani Campus
6. Basic functions of a maintenance
management system
1.
2.
3.
4.
5.
6.
Preventive maintenance
Plant and unit record(Equipment)
Inventory and spare parts control system, Purchasing system
Document record
Planning system for maintenance and work order routines
Technical/economic analysis of plant history, maintenance and machine
availability
BITS Pilani, Deemed to be University under Section 3 of UGC Act, 1956
7. Organizing the Maintenance
Function
Centralized maintenance department
Does all maintenance (PM & breakdown)
Decentralized Maintenance department
Useful if different equipment used in different areas of company
Contract maintenance
Used if little equipment or expertise
Operator ownership approach
BITS Pilani, Deemed to be University under Section 3 of UGC Act, 1956
8. Operator-Ownership
Approach
Operator does preventive maintenance
Equipment condition is their responsibility
Learns equipment better
Increases worker’s pride
Reduces repair time & PM costs
Maintenance department is backup
Handles non-routine problems
Provides maintenance training
Has plant-wide responsibilities
BITS Pilani, Deemed to be University under Section 3 of UGC Act, 1956
10. Maintenance Planning & Scheduling
Planning:
•
•
Management surveys show that the average productivity of
maintenance employees is between 25 and 35%.
This means that a craftsman has less than 4 hours of productive
time per 8-hour day due to poor maintenance management.
BITS Pilani, Deemed to be University under Section 3 of UGC Act, 1956
11. Maintenance Planning & Scheduling
The following are some of the most common wastes of
productive time:•
•
•
•
•
•
•
•
•
•
•
Waiting for instructions
Looking for supervisors
Checking out the job
Multiple trips to the stores
No special tools
Waiting for approval
Too many craft workers per job
Insufficient workers scheduled for the job.
Incomplete planning & communications
Waiting for equipment to be shutdown
Waiting for drawings from engineering
BITS Pilani, Deemed to be University under Section 3 of UGC Act, 1956
12. Maintenance Planning & Scheduling
On the average, 2 hours are lost every time worker is pulled off a job for any reason.
To prevent this major loss of productivity, it is necessary to implement some form of job
planning function.
The concept of job planning is to determine what is to be done and how it is to be done.
Job planning consists of two main areas:
1. Craft skills
2. Material required for the job.
These labor and material requirements may be converted to dollars to give an estimate
of the cost of completing the work order.
BITS Pilani, Deemed to be University under Section 3 of UGC Act, 1956
13. Maintenance Planning & Scheduling
Planning
Planning can be accomplished by the supervisor if there are relatively few maintenance
personnel.
If there are more than 20 craftsmen, planning is best done by separate maintenance
planners, otherwise the foremen have a tendency to do paperwork when they could
more profitably spend their time in supervising and directing the work of the craftsmen.
BITS Pilani, Pilani Campus
14. Maintenance Planning & Scheduling
Type of Work to be planned:
– Emergency maintenance and critical maintenance (work needed
immediately or within 24 hours) is seldom planned.
– These request are of short duration and are performed so quickly that there
is no time to plan them.
– These types of work orders should not be considered in planning functions
– Normal corrective or routine work orders should be the primary consideration
of the planning function.
– These work orders are received and placed in work backlog.
– As the workforce and materials become available to carry out the work, it is
scheduled.
– Included in this type of work are preventive and predictive maintenance work
orders.
BITS Pilani, Pilani Campus
15. Maintenance Planning & Scheduling
Type of Work to be planned:
• The other group of work requests that can be planned are the
shutdown, turnaround, or the outage work orders.
• For this type of work, it is important that the equipment be shut down and
overhauled in the shortest possible time.
• Only by accurate estimating and scheduling of these work requests can the
shutdown be successful.
BITS Pilani, Pilani Campus
16. Maintenance Planning & Scheduling
How to Plan Maintenance Work :
– Effective planning requires the planners to be skilled and knowledgeable in the craft area they
are planning; therefore, supervisors or top craftsmen will make the best planners.
– If an inexperienced individual is promoted to planner, the results of the planning program will
not be satisfactory. Instead of increasing productivity, you may find productivity decreasing.
– The planning begins once the work order is approved by management.
– It is then assigned to the planner, who carefully studies the job.
– The planner must decide the following: The crafts required,
The time required,
The materials required, and
Whether outside help in the form specialists, contractors, or special rental equipment is
required.
BITS Pilani, Pilani Campus
17. Maintenance Planning & Scheduling
How to Plan Maintenance Work :
–
–
–
–
–
–
–
When the planner is deciding on the required crafts, he must also decide not only the
number of craftsmen, but also the skill level required.
The time estimate for work order is important. If there is no time estimate, you will never
know the man-hours of work that is in the crafts backlog. Without this information, you
can never accurately determine the proper staffing levels for your plant.
The material required for the work order will determine whether it can be scheduled.
If the necessary materials are not available and the work order is scheduled, the
craftsmen will lose productivity looking for the spare parts and waiting for supervisor to
find them work that can be performed.
It is also necessary to plan the materials so that an accurate estimate of the cost of the
work order can be obtained.
The miscellaneous items to be planned are important to proper completion of the work
order.
If special skills are required from outside source, the in-house craftsmen may not be
able to complete the work order quickly or with necessary quality.
BITS Pilani, Pilani Campus
18. Maintenance Planning & Scheduling
Scheduling Indicators:
Within a maintenance strategy, you can use different
scheduling indicators to specify the type of scheduling you
require or to define a cycle set:
Time-based (for example, every 30 days)
Time-based by key date (for example, every 30 days on the
30th day of the month)
Time-based by factory calendar (for example, every 30
working days)
Performance-based (for example, every 50 operating
hours)
BITS Pilani, Deemed to be University under Section 3 of UGC Act, 1956
19. Benefits of Planning Maintenance
Long term plans insight
Decision making support
Optimizing connectivity among operation and maintenance
departments
Figuring out areas of cost reduction
Training areas and needs
BITS Pilani, Deemed to be University under Section 3 of UGC Act, 1956
20. Nature of maintenance problem
Maintenance can be classifies as follow
1. General classification of maintenance problems
1.
2.
3.
2.
Mechanical Failure
Thermal Failure
Chemical Failure
Classification of maintenance problem based on
time span
1. Short Run Maintenance Problem
2. Long Run Maintenance Problem
BITS Pilani, Deemed to be University under Section 3 of UGC Act, 1956
21. General classification
Maintenance problem
Mechanical Failure
Worn out bushes and bearings and other moving parts.
Fatigue of machine members
Creep of material at high temp
Excessive forced vibration, misalignments etc.
Thermal Failure
Overheating of the component
Lack of lubrication
Inadequate of cooling
Electrical insulation failure
Chemical Failure
Highly corrosive fluids containing abrasive particles
Failure of protective linings like glass , rubber etc.
BITS Pilani, Deemed to be University under Section 3 of UGC Act, 1956
22. Classification maintenance
problem based on time span
Short run production problem
Maintenance problem which are carried out in a sort period of
time are known as short run production system. It may be
hourly, daily ,weekly and monthly.
Example:Hourly- inspection of correct lubricant, level of
coolant, sharpness of cutting tool.
Daily- cleaning of m/c, tightening of nuts, correct
cooling, inspection of various indicators, minor adjustment of
parts.
Weekly- Major adjustment, lubrication, tightening of parts.
Monthly- checking for insulation, corrosion, safety
guards, checking of worn-out and distorted parts.
BITS Pilani, Deemed to be University under Section 3 of UGC Act, 1956
23. Maintenance Cost Control
Objectives of Maintenance and Maintenance Cost
During the years the maintenance function has not been seen as a
condition for production output. The previous approach has been
that maintenance is the necessary evil, one among the cost
generators in the organization. Very often the maintenance strategy
in plants has been to reduce the maintenance cost as much as
possible without thinking of the consequences.
Objective of the maintenance is , as priority one , to create an
availability performance which is suitable for production demands in
the organization. No mechanized/atomized company has yet
succeeded to produce with stopped equipment. Production buy
availability performance from maintenance.
BITS Pilani, Deemed to be University under Section 3 of UGC Act, 1956
24. Maintenance Cost Control
All enterprises and organizations are interested in lowering
maintenance costs. A very common delusion is that
• The product gives the income
• Maintenance costs money
Note: Maintenance which is not carried out ,will cost even more
than money .
BITS Pilani, Deemed to be University under Section 3 of UGC Act, 1956
25. Maintenance Cost Control
There are two ways of managing the maintenance
costs
1.
2.
Cost Controlled Maintenance
Result Controlled Maintenance
BITS Pilani, Deemed to be University under Section 3 of UGC Act, 1956
26. Maintenance Cost Control
Contd…
The cost controlled maintenance is not considered as modern
maintenance management, The reason why maintenance has been
treated as a cost controlled activity, Is often that engineers and
technical staff have had some dilemma to measure the results of
investments in maintenance in total economical terms. It is simple
to find the direct cost for maintenance but it could be difficult to
see the results.
The upper priority in the objectives of maintenance is to “keep
up planned availability performance at the lowest cost possible” .
This means that the long term results are important. The
maintenance cost must be put in relationship with overall results
achieved by maintenance in production facility.
BITS Pilani, Deemed to be University under Section 3 of UGC Act, 1956
27. Maintenance Cost Control
The maintenance cost can be split up in two different categories.
Direct maintenance costs -The costs are directly related to the performance
of the maintenance works
Indirect maintenance costs -Losses due to maintenance
BITS Pilani, Deemed to be University under Section 3 of UGC Act, 1956
28. Maintenance Cost Control
Direct maintenance costs
• Wages & Salaries
• Material Costs
• Administration Costs
• Costs for training
• Spare parts costs
• Contracted work forces
• Modification Costs
Indirect Costs
• Loss of revenue or other losses as a result of interruption to production as a
result of maintenance.
BITS Pilani, Deemed to be University under Section 3 of UGC Act, 1956
29. Maintenance Cost Control
Measurement of Maintenance Efficiency
Many times there are needs to measure the maintenance efficiency.
However, maintenance can not be measured by the cost it creates. There must be an
connection to the production out put some way. It is naturally impossible to
determine anything about the size of the direct costs. One method to control the
direct maintenance is to use the PM-factor. “P” stands for prime product produce and
“M” stands for maintenance cost. When using the PM-factor, the result of the
maintenance impact on the production is measured. How many products are
produced per a 1000 units of “maintenance money”.
Prime Production
PM – Factor
=
X
1000
Maintenance Cost
BITS Pilani, Deemed to be University under Section 3 of UGC Act, 1956