Today, in modern industry, equipment and machinery play a very important role in the production process. With the development of special and sophisticated machines, equipment and machinery cost, the idle time or downtime of the machine became very expensive. Therefore, it is very essential to maintain properly. Maintenance is an important factor in quality, which is a basis for competition. Inconsistencies in machines would lead to variations in products and defective parts that fail to meet the specifications. Therefore, a good maintenance management is important for the company’s success and for cost control.
Objectives of plant Maintenance
1. The objective of plant maintenance is to achieve minimum breakdown and to keep the plant in good working condition at the lowest cost.
2. Machines and other facilities should be kept in good condition so as to gain maximum profits with minimum interruptions. Maintenance division of factory ensures the availability of machines, buildings and services required by other sections of the factory.
Importance of Maintenance:
1. The importance of plant maintenance varies with the plant and its production.
2. Breakdown in machinery leads to inevitable loss of production.
3. Improper maintenance of machines will sooner or later require expensive and frequent repairs.
4. Plant maintenance plays a prominent role in production management because plant breakdown creates problems such as:
i) Loss in production time
ii) Rescheduling of production
iii) Damages in process materials due to sudden stoppage
iv) Need for over time
v) Temporary work shortages – workers require alternative work.
Types of Maintenance
a. Corrective or breakdown maintenance
b. Scheduled maintenance
c. Preventive maintenance
d. Predictive maintenance
Only breakdown maintenance and preventive maintenance are discussed in this section.
Corrective or Breakdown Maintenance:
1. Corrective or breakdown maintenance – in this type repairs are made only after the machine is out of order or when it cannot perform its normal function any longer. Example an electric motor will not start with a broken bell etc.
2. When the machine/equipment is out of order, the production department calls on the maintenance department to rectify the defect.
3. Maintenance engineers do not attend to the equipment again until another failure or breakdown occurs.
4. Breakdown maintenance practice is economical for those (non-critical) equipments whose down time and repair costs are less than with any other type of maintenance
5. Breakdown type of maintenance involves little administrative work, few records and comparatively small staff.
6. This type of maintenance is suitable or justified in small factories.
Preventive Maintenance (PM):
1. In case if machine breakdown, operations manager has no choice except repairs. On the other hand, to prevent such hazards the decision is taken to have regular scheduled inspections, machine adjustments, lubrication, and parts replacements, as a part of preventive maintenance (PM).
2. As system of scheduled, planned or preventive maintenance tries to minimize the problems of breakdown maintenance.
3. It locates weak spots in all equipments, provides them regular inspection and minor repairs thereby reducing the danger of unanticipated breakdown. The underlying principle of preventive maintenance is that prevention is better than cure.
4. It reduces the frequency and severity of interruptions to production caused by machine malfunctions. This objective can directly affect production capacity, production costs, product quality, employee and customer safety, and customer satisfaction. Reduces the total cost of maintenance by substituting PM costs in place of repair costs.
5. Improves the product quality by keeping equipment in proper adjusted, well serviced, and in good operating condition.
Advantages of PM:
1. Reduced breakdowns and connected down time.
2. Less time for repairs and reduced over time to the maintenance work force.
3. Greater safety for workers
4. low maintenance and repair costs
5. lower unit cost of manufacturing
6. Extends the useful life of machine
7. Less reserve of spare parts and reserve equipment
8. Better industrial relations because production workers do not face involuntary lay offs or loss of incentive bonus because of breakdowns.
Trends in Maintenance
Production machinery today is far more complex than it was a decade or two ago. Computerized controls, robotics, new technology has led to many changes. Special training programs have sprung up to give maintenance workers the skills necessary to service today’s specialized equipment.