Do you want a maintenance system that delivers Zero Failures?

Do you want it for all your plant?

Can you afford it?

Is it actually achievable?

The reality is that a zero failures operational environment (or very close to it) can be achieved, as is evidenced in the nuclear, submarine and aircraft industries. However, the cost is extremely high, both in terms of capital and revenue operating cost, and is not a cost-effective scenario in conventional manufacturing industry. What is important in all situations, however, is that an assessment of the acceptable level of failure has been carried out and that the maintenance system has been designed in accordance with the result of the assessment. 

There are some key steps in matching the maintenance strategy to the business objectives, none of them complex but which do require a understanding of the systems and techniques that can be brought to bear to control the probability of failure. A good starting point is to consider the fact that only 30% of the cost of maintenance is associated with what is generally called "fair wear and tear", and almost all of that can be predicted ahead of time such that maintenance interventions can be planned to be carried out in production windows of opportunity. The other 70% of maintenance cost results from a whole range of causes as shown in the attached chart. The conclusion from this is that control of failure rates is influenced more by external influences than by the maintenance strategy itself.

How is the 70% of unnecessary maintenance cost derived?

1. Unsatisfactory design will result in equipment that is not fit for purpose, or does not provide satisfactory maintainability. It could be that the process has changed and the original design does not meet the revised duty specification. For whatever reason, this level of maintenance will be perpetuated unless the design or the duty is modified. For similar reasons, the installation of the equipment may not be in line with the design specification, leading to unnecessary failures. Design and construction failings typically contribute around 12% of all maintenance cost.

2. Maintenance errors and omissions are directly responsible for about 8% of maintenance cost. This will mainly be as a result of unsatisfactory standards leading to early failure of equipment (generally referred to as self-induced failures). Almost all of this type of avoidable maintenance can be eliminated through good training and empowerment programmes.

3. Production are responsible for the largest proportion of avoidable failures of equipment, typically in the order of 30% of all maintenance cost, through abuse and maloperation. These losses can be virtually eliminated if the correct environment is established, where operators are directly responsible for ownership of their equipment and where maintenance and production work closely together to maximise equipment performance. The structure for this type of environment is generally referred to as Total Productive Maintenance. PRIME has developed an approach to defining the most effective ways of establishing this type of environment, but without slavishly "Implementing TPM".

4. Finally, management contributes about 7% of avoidable maintenance, by failing to commit to the specified systems of asset care and by failing to establish good management control over plant operations.

In developing a maintenance strategy for any manufacturing operation it is important that all of these imposed failure causes are addressed, as well as the necessary ("wear and tear") causes. For almost all of the causes there will be a means of preventing unexpected failure. The decision then rests with the maintenance manager to implement the failure-avoidance mechanisms that are cost-effective in the particular set of circumstances that prevail in his own company. It is important to remember that the key driver for maintenance is not to prevent failures but to prevent the consequences of failure when they are unacceptable to the business. For that reason there cannot be a standard maintenance regime for any particular piece of kit that is appropriate for all users (no matter what the manufacturer leads you to believe!) --  failure-based maintenance has a role to play in the maintenance manager's armoury, alongside CBM and intrusive PPMs.

If you would like to learn more about how to set the optimised maintenance strategy for your plant, contact PRIME at prime00@talktalk.net

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