Maintenance Objectives

In British industry, the maintenance plan has often evolved rather than being consciously set-up resulting in an over reliance on breakdown and fixed time maintenance (planned maintenance). Historically plant equipment has been robust and less automated than modern equipment making it relatively easy to work on. These plants have relied on large and expensive maintenance departments to enable rapid attention to breakdowns. Single-line single-product plants with no standbys have allowed profitability to be increased through the economies of scale. On the downside, this has resulted in ever increasing breakdown costs. In this changing environment, historical maintenance plans cannot provide the required level of plant performance.

Maintenance Goal

The goal of any well run maintenance organisation is to have the lowest cost of the sum of two quantities, i.e.:

• Maintenance labour and material
• Production loss reduction resulting from an inadequate maintenance program (which includes lack of ability to produce, and value added material that is lost as a result of a break down).

Maintenance itself can result in excessive downtime and costs. This results from the requirement to take the machinery off-line to carry out (possibly unnecessary & invasive) maintenance. The danger of infant mortality after it has been put back on line again and also the cost of the maintenance action itself contributes to costs. Achieving the lowest cost is an optimisation technique shown graphically in below.

Companies should be able to put a cost to their loss of production resulting from equipment down time. This figure added to the maintenance budget results in the total costs as shown. When maintenance costs are at a minimum the cost of lost production is at its highest. As maintenance effort and costs are intelligently increased the production loss gradually decreases until the lowest combined cost is achieved. This is the maintenance goal. Maintenance effort applied beyond this point, increases costs. Maintenance can increase costs because of the need to take equipment off line to carry out maintenance, infant mortality after being put back in service, etc. There are also the costs of the maintenance itself with labour and material costs.