Introduction.
The needs for maintenance increases with technological advancement in production facilities, in order to achieve sustained and increased production level, rigid production schedules, increase machine utilization and market competitiveness.
Maintenance is a key process of production activity, the lack of which would result in damages that would be costly in terms of repairs and time frame. The penalties for failure to do so are incapable. Therefore there is need to introduce planned and effective preventive or corrective maintenance system.
Excessive machine breakdown shortened machine life span, loss of production output, lower quality of facilities/ products, excessive overtime cost and loss of profit are bound to characterize its activities.
Companies stand to gain a lot if they can inculcate a maintenance culture. An efficient maintenance scheme is not only an integral part of the production, leading to increased output and reduced cost, but also a catalyst for the attainment of efficient utilization of installed production facilities, a major continuity factor to the promotion of economic growth.
Types of Maintenance.
1. Planned Maintenance: This is further broken into:
i. Effective Preventive Planned Maintenance
ii. Corrective Planned Maintenance
Planned maintenance, the vehicle for productivity, noting that before the present economic crisis in some countries of the world. Some countries of the world example Nigeria did not possess any record of maintenance culture but instead prefer to discard damaged machinery in preference to new ones. However, the downturn in the economy has now compelled us to look inward, gone are the days when we would discard machinery for a new one. Today, the replacement values of a high number of our plants and machinery are simply prohibitive.
Therefore, production companies have been advised to adopt a planned maintenance culture as opposed to one that is not planned. Planned maintenance is further broken into preventive and corrective planned maintenance.
The first seeks to prevent breakdown and any emergency repairs that may lead to the downturn by assuring that inspections, adjustment, overhauls, testing repairs and replacement to worn out parts are carried out as planned intervals to avoid disruption of service.
On the other hand, the corrective maintenance involves the restoration of a facility to an acceptable standard, when it has fallen short of its expectation as a result of progressive deterioration or sudden failure.
1. Effective Preventive Planned Maintenance.
As earlier stated the effective preventive planned maintenance prevent breakdown and any emergency repairs that may lead to the downturn by assuring that inspections, adjustment, overhauls, testing repairs and replacement to worn out parts are carried out as planned intervals to avoid disruption of service.
There are two approaches to the maintenance of plant or equipment.
i. Allow it to run until it breaks down and then carry out repairs.
ii. Regularly test and inspect it:-
(a) Replace worn parts
(b) Oil and grease adequate parts
(c) Revanish windings
This must be done because it will prevent breakdowns as far as possible. This approach depends in part on the process being carried out. A break down may result in a period of non-production with loss of revenue from the plant. It may cause considerable damage to the associated plant.
The breakdown of an oil pump providing lubrication for a gear-box on a large piece of equipment could cause the gear-box to be wrecked. The failure of a circuit breaker attempting to open to clear a fault could cause severe burning and disruption of the system. On the other hand, the failure of a vacuum cleaner motor in the house would probably be merely inconvenient.
Preventive maintenance does not generally prevent breakdown altogether but minimizes their incidence. Such work can often be carried out during periods of light loading on the factory or during the holidays of the production staff rather than at the most inconvenient time, which is when breakdown always seem to occur.
However, routine maintenance allows the workforce to be employed steadily for periods of the year instead of day and night, occasionally during periods of breakdown. The frequency of testing and inspection will also depend on one or more of the following factors.
1. Equipment and the environment.
For instance, a fully submersible pump with an electric drive working in an acidic fluid, running intermittently for 24 hours each day would be more likely to fail in service than a small motor is driven fan, running one shift per day, used to ventilate a small workshop in which light assembly work is carried out. The interval between checks on the submersible pump would need to be shorter than for the fan.
2. The plant history.
Where a plant has a record of failure at regular intervals or when inspections formerly took place, worn parts were generally found. The periods between inspections would be shortened to allow parts to be replaced before conditions can be created which would lead to break-down.
3. Plant running hour.
Electronic apparatus using printed circuit boards might be allowed initially to run to failure. In the light of the experience gained, failure board or unit charges might be made after less than the mean time to failure.
Where electric motor and generator brush gear is concerned, the experience will show how many running hours' results in brushes wearing down to unsafe lengths. Having established this period, brushes will be damaged after the plant has run say 20% less than the critical time.
4. Availability of Plant for testing.
Certain plants are only available for testing and maintenance at fixed intervals so that all work other than breakdown maintenance must be carried out at this time. Steam boilers, for example, may run for 14 or 26 months, according to type, between statutory inspections. This may fix the period between inspections for non-duplicated auxiliary equipment.
The plant maintenance engineer generally plans at least one year ahead when the running programme for the factory is known. The availability of spare parts has to be checked and orders placed were thought necessary.
Inspection and tests are detailed under "essential" and "optional" headings, and a length of time and number of staff available will determine how many jobs can be carried out simultaneously. The progress has to be such that the whole plant can be returned to service when required for production.
Failure to do so results in financial loss and the amount of this loss is one measure of the effectiveness of the maintenance department. Some of the optional jobs may have to be held over until another time.