Effective Programs for Improving Maintenance Control
In this section, four engineered maintenance programs are briefly outlined. These programs offer sound courses of action that can be adopted to enhance maintenance control. The objective of these programs is to improve plant availability, reduce cost, and improve OEE and product quality. These programs are listed below:
1. Emergency maintenance; 2. Reliability improvement; 3. Total productive maintenance; and 4. Computerized maintenance management.
5.7.1 Emergency Maintenance
Emergency maintenance refers to any job that should be attended to immediately. Emergency maintenance, by its nature, allows very little lead time for planning. The amount of emergency maintenance must be minimized and it should not exceed 10% of the total maintenance work. The maintenance department must have a clear policy for handling emergency maintenance. One of the following offers an approach to handling emergency maintenance:
1. Preempt the regular schedule and perform the emergency maintenance, then pick up the backlog with overtime, temporary workers or contract maintenance; and 2. Assign dedicated crafts for emergency maintenance based on the estimated emergency maintenance load. It is an accepted practice in industry to allow 10–15% of load capacity for emergency work.
The first approach is expected to result in increased workforce utilization; however, the second approach offers the ability to respond quickly as needed.
5.7.2 Reliability Improvement
A reliability engineering program offers a sound alternative for improving the maintenance function. It can be used as an option to improve maintenance performance. Critical and major equipment history files must be maintained and estimates for mean time between failure (MTBF) must be calculated. The frequency of emergency maintenance is a function of the failure rate of this equipment. It can be estimated for a period of operations lasting n hours, there will be n/MTBF emergency maintenance actions. The longer the MTBF the lower the number of emergency maintenance incidents. Reliability centered maintenance (RCM) can be utilized to enhance maintenance polices and improve equipment reliability. In RCM, the maintenance program is developed on the basis of the concept of restoring equipment function rather than bringing the equipment to an ideal condition. RCM has been applied successfully in the commercial airline industry, nuclear reactors, and other power plants.
5.7.3 Total Productive Maintenance
Total Productive Maintenance (TPM) is an approach to maintenance developed in Japan that brings the tools of total quality management (TQM) to maintenance. The aim of TPM is to reduce six categories of equipment losses to improve overall equipment effectiveness (OEE). The six major causes of equipment losses, according to Nakajima (1988) are:
1. Failure; 2. Set-up and adjustments; 3. Idling and minor stoppage; 4. Reduced speed; 5. Process defects; and 6. Reduced yield.
TPM empowers operators and uses multi-skilled crafts to minimize response time and perform productive maintenance. The implementation is expected to assist in improving maintenance effectiveness and control.
5.7.4 Computerized Maintenance Management and Information Technology
High technology production units (machinery/equipment) require high technology maintenance and control systems, so maintenance systems must move in new directions if manufacturers/service enterprises hope to keep that expensive production/service equipment up and running. Information technology hardware and software enable maintenance management to automate and process activities in a speedy manner. Above all enable maintenance managers to retrieve and process information that can be used for effective maintenance planning and control. Every company must use a basic computerized maintenance system. It is most effective to integrate such systems with organization enterprise resource planning (ERP). Many of the existing ERPs have maintenance modules. Finally, any system that is installed should serve the maintenance personnel rather than forcing these people to serve the system, so all such systems will require extensive personnel training.