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laboratory of the computer using actual failure data from existing plants.
Models provide a way to search for lowest cost operating conditions by predicting the outcome of conditions, events equipment (Metropolis and Stanislaw, 1949).
2.5.8 Lubricant – related failure
Proper lubrication is essential in any gearing system. Lubrication has two principal functions; to minimize rubbing friction and to carry off heat. If the lubricating film thickness is adequate and the lubricant is clean, wear will be minimized. The lubricant must sometimes provide protection against corrosion.
If the lubricant fails, its internal chemical compound can break down with time, with heat or by unforeseen reactions with chemicals from its ambience. Several types of gear failure can be traced back to lubricant failure (Alan, 1991).
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some organizations, rigidity of rules and procedures prohibits the creative – thinking and implementation of proper maintenance policies.
Maintenance aspect is more important in machines due to their non-uniform pattern of wear and tear which depends on a large number of factors. Therefore, concentration will be on machine maintenance in this section.
Every machine is thoroughly tested and inspected by the manufacturers before delivery and the purchaser before it is accepted. When in use, however it will be subjected to wear and tear hence proper attention should be given to protect the machine and its components from undue wear and failure. A proper attention means lubrication, cleaning, timely inspection and systematic maintenance.
Maintenance of a machine means efforts directed towards the up-keep and the repair of that machine(Wang, Liu and Chen, 2010).
Every machine will require repairs even if it is best designed, hence the repair must be done at such a time when it may have least disruption, that is machine may be repaired when it is not used or its use may be postponed without affecting the production of the goods. Therefore, checking the machine is generally done when it is not in operation, so that the defect, if any, can be immediately and easily rectified without causing extensive damage.
In this way, we say that maintenance is responsible for the smooth and efficient working of equipment and helps in improving its productivity. It also helps in
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keeping the machine in a state of maximum efficiency at needed times with economy.
Success of any organization largely depends on proper selection of personnel for the operations. Production depends largely on the maintenance of plant and equipment. Hence, the organization of the maintenance wing should be such that a proper maintenance and overhauls, can be done economically and effectively. Maintenance wing is generally given an important position in the organization. Maintenance functions performed with their input, and accepted results as output. These outputs are controlled through different parameters and based on feedback of these parameters further controls can be applied till desired maintenance results are obtained (Tan and Raghavan, 2010).
2.6.1Evaluating maintenance performance
The following parameters should be considered while evaluating maintenance performance:
i. Labour productivity: Actual utilization of maintenance crew is compared with that of norms decided for the purpose.
ii. Equipment Availability: Considering that machine is not idle, Availability= Operation Time
Operation Time + Maintenance Time
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iii. Time spent on preventive maintenance v/s repair time
iv. Cost Parameter. It compares the cost of wages and material on (1) preventive maintenance, and (b) breakdown maintenance.
v. Number of job card (requisition for maintenance) in hand v/s job cards completed, along with the number of effective man – hours involved
vi. Overtime analysis: This is the ratio of overtime hours to the total maintenance hours.
vii. Condition of equipment: To be identified by level of maintenance like M.T.B.F., level of noise, tolerance, vibrations etc.
viii. Comparing Budgeted expenditure and actual expenditure.
ix. Percentage of maintenance cost of the value of products output.
2.6.2 Involving other department for maintenance
Maintenance is carried out to retain an item in, or restore it to, an acceptable standard of performance. The function of the maintenance department is to keep the facilities of the organization in an optimum operating condition so that the intended functions are performed satisfactorily (Zio, 2009). The aim of maintenance is to reduce the frequency and severity of failure so as to ensure the availability and efficiency of the existing plant, equipment and buildings at an optimum level. In order to make the maintenance function more effective, other departments such as design, engineering, purchasing, finance, research
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and development, and production should be involved. This concept of involving other departments for maintenance is termed “terotechnology”. It is concerned with the specifications and design for reliability and maintainability of plant, equipment, building with their installation and commissioning, modification and replacement, along with the feedback of information on all these aspects (Wagner, Shamir and Marks, 1987).
2.6.3 Objectives of maintenance
The main objectives of maintenance are as follows:
a. To maximize the availability of plant, equipment for productive utilization.
b. To extend the lifespan of plant/equipment by minimizing their wear and tear and deterioration.
c. To reduce the cost of loss in production due to break down.
d. To ensure safely of personnel.
e. To provide information on the cost and effectiveness of maintenance (Tam and Raghavan, 2010).
2.6.4 Overall systems performance
The overall performance of a production system is determined by the qualitative properties of the system. These properties are found in all the different components of the system in designing, the most difficult task is the balancing
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of the properties and costs of each of the components in order to achieve a system, which can be operated at optimal production during the calculated life time of the system.
Terms used in the above model are explained here below in brief.
1. Overall systems performance: This is total production and economic