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Maintenance Theory

I read a few books on maintenance. I must have chosen the wrong books as intellectual bite was totally missing. The message coming from these books was that, in the past, maintenance consisted of waiting until the equipment broke down and then fixing it.

The books argued that modern equipment was less robust than in the past, more complex, and needed more care. They advocated time-based preventive maintenance as their solution. Their thesis in the books was that we could prevent all failures. Failures were themselves a symptom of some shortcoming or failure in the maintenance systems. The books suggested as best practice targets, a profile of 90% time-based preventive work and 10% breakdown work. This thesis and the preventive maintenance approach had been adopted in the electrical maintenance group. In this chapter, we will show how ineffective this approach can be by looking at a couple of case studies.

Preventive Maintenance of Motor Starters

My initial questions about what my electrician horde did show that a team of a supervisor and six electricians spent every day of the working week checking the condition of 415-volt motor starters. Their goal was early identification of overheating due to loose connections. Any problems could then be rectified and failure prevented.

A significant planning and scheduling effort went into this activity, with a planner working almost full time on it. He spent his day arranging with production for the release of the equipment and making sure spares were available in case a problem was found. I think that the intention was for each starter to be checked every two years.

I questioned the planner and supervisor on these activities. They were unembarrassed when they revealed that over the last three years of checking they had:

  • • found one loose connection that could have become a fault
  • • found two issues which needed some non-urgent attention
  • • caused four faults by fiddling inside the starters; these had caused a loss of production.

They argued that this showed that our maintenance systems were robust and we had excellent strategies in place. I suggested to the supervisor and planner that perhaps the payback was not commensurate with the checking effort and asked whether it was sensible to continue. Such talk was clearly heresy and they looked stunned. Obviously I didn't understand maintenance. It took almost a week of debate to convince them that this effort should be stopped. The moment of truth came when I asked them if they would do this

Cost-Benefit Balance

Figure 20.1 Cost-Benefit Balance

work if it were with their own money.

We stopped this activity and replaced it with a check of the starters at the three yearly shutdowns when the motors were not in use. Only rarely was anything ever found. However, as the check consisted only of opening a starter door and looking inside, we carried on; see Figure 20.1.

 
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