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2.1 Maintenance Work in the Manufacturing Industries:
Maintenance in manufacturing industries includes all the activities involved in keeping a system of equipment and machines working with a best possible condition (Heizer, 2000). It is a combination of actions carried out to retain an item in, or restore it to, an acceptable condition. The objective of maintenance in the manufacturing industries is to maintain the capability of the production and support systems at the highest possible level while controlling their operational and maintenance costs (Heizer, 2000). A good maintenance system helps in maintaining the manufacturing system performance and protects its environment from expected dangers.
Maintenance system in manufacturing industries is usually composed of several types of maintenance activities that should be handled separately. Some of these types are routine maintenance activities, preventive maintenance activities, and emergency maintenance activities (Niebel, 1994). Routine maintenance activities are often called scheduled maintenance, because each activity in this category needs to be scheduled and it is required to be performed with in specific intervals. Examples of the routine maintenance activities are oiling machinery, changing bearings, coolant and others.
Preventive maintenance activities (planned maintenance), on the other hand, involve performing routine inspections, servicing, and keeping facilities in a good condition. These activities are intended to build a system that will find potential failures and to make changes or repairs that will prevent the occurrence of a failure. Preventive maintenance is much more than keeping machinery and equipment running. It also involves designing technical and human systems that will keep the productive process working with in tolerance. The emphasis of preventive maintenance activities is on understanding the process and keeping it working without interruption (Niebel, 1994).
Breakdown maintenance activities (Emergency maintenance) occur when important equipment fails and they are preformed on an emergency basis. In addition, they must be given the highest priority among other types of maintenance activities. The breakdown maintenance activities are expensive, because they need a lot of time from the maintenance workers and they cause losses in production. For this reason, breakdown maintenance activities must be avoided. The way to avoid breakdown maintenance activities is by performing good routine and preventive maintenance (inspection and servicing) that can predict breakdowns before they occur and prevent the production system from these breakdowns. A performance report for maintenance would help in the process of avoiding breakdown maintenance by including how much emergency maintenance was performed, with the goals of eliminating this type of maintenance as possible (Niebel, 1994). The businesses nowadays has nearly eliminated breakdown by predicting and repairing failures, before they occur and they use to do that the following tools:
1) Vibration analysis.
2) Heat recordings.
3) Machine records :
a) Type of repair
b) Oil consumption
4) Automatic lube systems.
5) Instrumentation for flow, temperature, amp, etc.
6) Replacement part inventory with reorder points and reorder quantity.
7) Plug-out / plug-in replacement units.
8) Backup equipment.
2.2 The Objectives of the Maintenance Work in the Manufacturing Industries:
Maintenance is function in an organization that operates in parallel with production (Duffuaa, Bin-Daya, 1995). The primary output of production is the desired product and its secondary output is demand for maintenance, which is in turn an input for the maintenance function. Maintenance results in a secondary input to production in the form of production capacity, while production manufactures the product, maintenance produces the capacity for production. Therefore maintenance affects production by increasing production capacity (Duffuaa, Bin-Daya, 1995). This relationship is shown in Fig 1.
There should be a sound relation between maintenance objectives and production goals. This relation is reflected in the action of keeping production machines and facilities in the best possible conditions. Maintenance objectives can be stated as follows:
Figure 1.1 Production Maintenance Relationships (Adapted from Duffuaa, Bin –Daya, 1995)
1) Improving machine and labor productivity.
2) Reducing down time.
3) Reducing breakdowns and emergency shutdowns.
4) Conserving the energy usage.
5) Controlling the usage of spare parts and maintenance materials.
6) Assuring a safe and clean environment for plant employees.
7) Maximizing production and keeping facilities at the lowest cost and the highest quality.
2.3 The Importance of the Quality Maintenance Work:
Quality of maintenance activities is important issue, since it affects the equipment performance and consequently the quality of the final product. In particular, performing maintenance activities in a good quality assures the maximum availability of the equipment, in addition to, assures that the equipment reach its desired level of performance. This means that performing a good quality maintenance work will prevent the production system from performing the maintenance work within a period less than the expected period to perform such a work.
Maintenance has been regarded as a secondary activity compared to production. A possible reason for that is in the output of the maintenance being difficult to define and measure in the short-term. Yet the important role of maintenance has been recently realized for maximizing production by keeping machines and facilities at the highest quality through extending equipment life cycle. It has been also recently realized that the maintenance quality has a significant effect on reducing downtime and breakdowns together with conserving the energy usage. The quality of maintenance output has a direct link to product quality and the ability of the company to meet delivery schedules. It is the responsibility of the organizations top managers and engineers to establish and develop maintenance testing and inspection standards for controlling the quality of maintenance output. They should tie their maintenance activities to their products.
They can rely on documentation of maintenance procedures and inspection reports for maintenance quality improvement.