Computer Aided Maintenance in Production and Operation Management

For effective discharge of the maintenance function, a well designed information system is an essential tool. Such systems serve as effective decision support tools in the maintenance planning and execution. For optimal maintenance scheduling, large volume of data pertaining to men, money and equipment is required to be handled. This is a difficult task to be performed manually. For a planned and advanced maintenance system use of computers is essential. Here programmes are prepared to have an available inputs processed by the computer. Such a computer based system can be used as and when required for effective performance of the maintenance tasks. There are wide varieties of software package available in the market for different types of maintenance systems.

A computerised maintenance system includes the following aspects:

  • Development of a database
  • Analysis of past records if available
  • Development of maintenance schedules
  • Availability of maintenance materials
  • Feedback control system
  • Project management.

Following are some computer based maintenance systems which can be implemented:

Job card system: It is essential to prepare a job card for each component to record the maintenance work carried out or the work to be done. Job card shows the plant code, equipment code, the job code, the nature of the jobs, the start time and finishing time of the card, man-hour spent and etc. The use of computers facilitates the issue of job cards, recording of job history and control of manpower.

Spare part life monitoring system: Under this system, information about a spare part such as its description, anticipated life and date of its installation in equipment is recorded. As and when a particular sparepart is replaced during breakdown failures or scheduled maintenance, the updating of this information is done in their respective files stored in the computer. This helps to prepare the following reports:

  • Spares repeatability in various machines indicating the performance of such spare parts.
  • Comparisons of the actual life with the estimated life of the spare parts.

Spare parts tracking system: In most of the cases maximum time is consumed in procurement of spare parts. The total time required to rectify the breakdown is summation of the time to identify the cause of the failure, time to determine the requirements of spare parts, time to procure spare parts and the time to rectify the failure. In a computerised system, the spare part tracking system is beneficial in getting required material at the earliest. A spare part file is created that contains the information about the material code, spare part identification number, the assembly or sub-assembly number and the place where the spare part is used. This helps in knowing the current position about a particular spare part and facilitates timely requirement for future demands.

Computer aided configuration

The first computer-aided maintenance software came from DEC in the 1980s to configure VAX computers. The software was built using the techniques of artificial intelligence expert systems, because the problem of configuring a VAX required expert knowledge. During the research, the software was called R1 and was renamed XCON when placed in service. Fundamentally, XCON was a rule-based configuration database written as an expert system using forward chaining rules. As one of the first expert systems to be pressed into commercial service it created high expectations, which did not materialize, as DEC lost commercial pre-eminence. [1]

Help Desk software

Help desks frequently use help desk software that captures symptoms of a bug and relates them to fixes, in a fix database. One of the problems with this approach is that the understanding of the problem is embodied in a non-human way, so that solutions are not unified.

Strategies for finding fixes

  1. The bubble-up strategy simply records pairs of symptoms and fixes. The most frequent set of pairs is then presented as a tentative solution, which is then attempted. If the fix works, that fact is further recorded, along with the configuration of the presenting system, into a solutions database.
  2. Oddly enough, shutting down and booting up again manages to ‘fix,’ or at least ‘mask,’ a bug in many computer-based systems; thus reboot is the remedy for distressingly many symptoms in a ‘fix database.’ The reason a reboot often works is that it causes the RAM to be flushed. However, typically the same set of actions are likely to create the same result demonstrating a need to refine the “startup” applications (which launch into memory) or install the latest fix/patch of the offending application.
  3. Currently, most expertise in finding fixes lies in human domain experts, who simply sit at a replica of the computer-based system, and who then ‘talk through’ the problem with the client to duplicate the problem, and then relate the fix.

Source: KumarAnil, Suresh N. (2009), Production and operations management, New Age International Pvt Ltd; 2nd Ed. edition.

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